H91 to H92 Horn Swap - The Results

[toddalin]

The Results

Linda went off to meditation so I fired up some pink noise to see what had transpired. The speaker and microphone were in the same positions as in the prior test (~1/4”). Unforetunately, because the wires for the crossover were run out the port for further testing, this latter test does not have the grill cloth, whereas the prior test did. (Hindsight. :banghead:)

Again, I dialed the horn and tweeter to about the smoothest response. In this case I also did the horn both in and out of phase. I also did this with the tweeter, but that made little difference and I didn’t photograph those changes. I did note that when the horn was hooked up in phase, I had to turn the tweeter up a hair to get it to balance out as opposed to when the horn was out of phase. I think this could infer that the horn is a little louder when connected in phase with the woofer requiring the tweeter to be elevated to match it.

This first picture shows the horn in phase with the woofer (i.e., +s on reds). Note the 800 Hz point and lower is depressed, but the area to the right is not to bad.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_Phasing002.jpg

This second shot shows the horn with reversed phase. In this case the 800 Hz band is stronger, but the area to the right is depressed. To me, the first shot (both +s on red) looks to be the preferred phasing based on the surrounding areas of the curve.

(In the past, had I not been using the Behringer, I would have played an 800 Hz tone though the speaker and probably concluded that the preferred phasing was not. :banghead:)

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_Phasing001.jpg

For contrast, this shot was the before also using the preferred phasing. The H91 actually looks to be smoother between 1K and 3K.
http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Existing_Woofer_H91_and_075.jpg

[Beowulf57]

Okay...now to some listening. How does the longer horn sound with music?

[Zilch]

I always use 30 dB range; the fundamental response is more apparent with the additional smoothing.

H91 shows its characteristic midrange emphasis; H92 is flatter there.... :yes:

[toddalin]

I always use 30 dB range; the fundamental response is more apparent with the additional smoothing.

H91 shows its characteristic midrange emphasis; H92 is flatter there.... :yes:

Agreed, but the 15 dB range shows the resolution of the areas of interest.

[toddalin]

Okay...now to some listening. How does the longer horn sound with music?

I've listened to Brothers in Arms (original) and it sounds good. (Only one channel is done so far.) It didn't sound bad before. It obviously hasn't filled the hole. I may be able to take the crossover a little lower now with the longer horns and will try adding a little capacitance on the horns.

[Ian Mackenzie]

I am not sure what crossover use are using but the equivalent L300 would be the best bet to sort out the hole.

Getting the phase shift right at that frequency is critical to obtaining a smooth response. Save your time and use the factory engineered LC values.

[4313B]

Greg concurs that his 630 Hz problem is most likely a box problem but can't remember if the L200 was a problem box or not, that was just too long and a thousand models ago.

The 2235H does not have a hole in its response at 630 Hz nor does the proper alnico structure reconed as a 2235. But we already knew that didn't we. The posted FR curve of the 2235H (http://audioheritage.org/vbulletin/showthread.php?t=10651) in the EDS stands. The alnico structures will develop a broadband 2 to 3 dB sag but that's just life, double up on the amplifier power.

[Beowulf57]

I've listened to Brothers in Arms (original) and it sounds good. (Only one channel is done so far.) It didn't sound bad before. It obviously hasn't filled the hole. I may be able to take the crossover a little lower now with the longer horns and will try adding a little capacitance on the horns.

Where is your crossover point at present? Also, when you test the results using material that exposes the hole, try reversing the phase of the horns and see which way sounds better to your ears: when I switched from the H91's to the H92's, I found the sound better with the phase reversed (my test was simply listening to dialogue on satellite programming and it was more intelligible in phase for the H91's and out of phase for the H92's).

Also, attached for anyone interested is an .xls file in zip which provides a calculator for room frequency peaks and nulls: just plug in your room dimensions and seating position dimensions and check row 27 for the problem frequencies. Lots of other data as well.

[grumpy]

yeah... not that the EDS needs my concurrence, but I've posted plots from a 4430
system that match them pretty well... even with my level of experience/methods.

Semi-random thoughts:
Would it be a worthwhile test to stuff/block the ports and ignore the response change
down low? (if there's an internal box resonance that's escaping through the ports...
understanding that it could also come through the cone). Certainly simple enough.
Apologies if this has been done already.

Cabinet internal width is pretty close to one wavelength at 630Hz... centered in the
baffle, that would put it at a null. A test septum (bit of a pain) might blow or support
this thought (as might someone with more experience in this area).

Has anyone else w/L200 cabs measured this type of response?

(Beowulf.. good ideas, but I believe the crossover is significantly higher... hence the problem)

[toddalin]

I am not sure what crossover use are using but the equivalent L300 would be the best bet to sort out the hole.

Getting the phase shift right at that frequency is critical to obtaining a smooth response. Save your time and use the factory engineered LC values.

I don't think that my values are that different than the factory values. The 33 mfd and 7 ohm on the Zobal network were subsequently changed to a 20 mfd (like the L300) and 15 ohm to bring the woofer up a little in that area of the frequency band, and the 1 mfd on the tweeter was removed from the tweeter.
I belive that Heather is using something similar, though not identical.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/xover_schematic.jpg

And here is the l300 network and it is very similar:
http://www.jblproservice.com/pdf/Network%20Schematics/3133A%20Network.pdf

I don't believe this to be a phasing issue of the crossover as I noted that I get this same response just connecting the woofer directly to the amp with no crossover.

[Ian Mackenzie]

Try the woofer on an a large baffle

[Beowulf57]

Cabinet internal width is pretty close to one wavelength at 630Hz... centered in the
baffle, that would put it at a null. A test septum (bit of a pain) might blow or support
this thought (as might someone with more experience in this area).

Has anyone else w/L200 cabs measured this type of response?

(Beowulf.. good ideas, but I believe the crossover is significantly higher... hence the problem)

Ahh, yes, my crossover is at 500Hz. Still, calculating the room modes would show whether there is an exacerbation of the dip due to a null at the seating position.

[Zilch]

Do I recall that Grumpy brought over a "Real" 2235H and the problem remained?

I investigated this problem in another thread here. It went away when I pulled back and put the mic on the floor.

Does tipping the box so the baffle is vertical alter the situation?

[Ian Mackenzie]

The problem is these measurements are not gated so what made be heard and measured at the listening position with the whole reverberant field may well be different to this static measurement.

[Beowulf57]

The problem is these measurements are not gated so what made be heard and measured at the listening position with the whole reverberant field may well be different to this static measurement.

:thmbsup:

[grumpy]

re Zilch's comments: I did bring over a 2235H... we probably tested with it. I do recall
putting the measurement mic on the floor and seeing the effect going away or being
reduced, but it gets fuzzy (in my brain) beyond that.

In use was a swept-sine stimulus and recording s/w package... one can set an arbitrary
window on the calculated impulse response and modify the sweep rate
to include or exclude some level of room response (FuzzMeasure for Mac).

The Behringer was not in-house at the time (IIRC).

[toddalin]

re Zilch's comments: I did bring over a 2235H... we probably tested with it. I do recall
putting the measurement mic on the floor and seeing the effect going away or being
reduced, but it gets fuzzy (in my brain) beyond that.

In use was a swept-sine stimulus and recording s/w package... one can set an arbitrary
window on the calculated impulse response and modify the sweep rate
to include or exclude some level of room response (FuzzMeasure for Mac).

The Behringer was not in-house at the time (IIRC).

Yes, it has been a year since the re-recharge, and a year before that we did the initial testing so it is a little fuzzy.

We did move the mic around varying the measurements, but the perponderance of them had the dip.

I don't think we ever put the real 2235 in the cabinet. (No sense in putting a screwdriver through the cone which is always my fear with mounting/dismounting.) I think we used it for reference in the WT-2 tests.

I note that the "Results" pics are missing a little in the area around the 630 Hz range that was there in the "Before" pic. When I put it all back together, I found that big piece of pink fiberglass sitting on top of the other cabinet, so maybe it was doing a little somethin' somethin' in there. When I revise the crossover, I'll be sure to put it back in the cabinet. I'll also try some of the other ideas (e.g., tilt to vertical) that were suggested.

With regards to the potential hole being a problem with the actual speaker, the thought was perished by some because a graphic response prepared ??? years ago shows a linear response.

But, as has been noted here recently, JBL hasn't made cones for these in over 30 years and they were done by outside vendors. Vendors change over time and while they are supposed to meet a certain specification, well..., even raw materials change over time.

How about someone with the proper equipment do a sweep of one of the current batch of cones?

[grumpy]

How about someone with the proper equipment do a sweep of one of the current batch of cones?

I did that... Edgewound reconed a few for me, well after yours were done @ OCS.

In a 4430 cab, in my house,... no such notch (w or w/o crossover... nearfield or listening pos).
I still have the plots on a system at home if they're not still posted here.
An independent sweep couldn't hurt.

Happy to come back over some time... you define the tests, drive the software if you
like, and we'll make it happen.

[toddalin]

I did that... Edgewound reconed a few for me, well after yours were done @ OCS.

In a 4430 cab, in my house,... no such notch (w or w/o crossover... nearfield or listening pos).
I still have the plots on a system at home if they're not still posted here.
An independent sweep couldn't hurt.

Happy to come back over some time... you define the tests, drive the software if you
like, and we'll make it happen.

I've gotta pop the woofer out to pop the crossover back in after I finish tweaking so I'm down with that if we want to test the actual speaker. Any ideas on how testing should be performed? (We already have WT-2 results.) Maybe just put the thing up on a dolly and wheel it outside for testing. Maybe even down to the curb and...

Oh wait, Mark already did that with the L300s and ended up with some ??? replacements. :D

[4313B]

With regards to the potential hole being a problem with the actual speaker, the thought was perished by some because a graphic response prepared ??? years ago shows a linear response.No one perished anything that I am aware of.
But, as has been noted here recently, JBL hasn't made cones for these in over 30 years and they were done by outside vendors. Vendors change over time and while they are supposed to meet a certain specification, well..., even raw materials change over time.I suspect that most people are betting on the L200 box, not the driver.
How about someone with the proper equipment do a sweep of one of the current batch of cones?I said I would...

I've gotta pop the woofer out to pop the crossover back in after I finish tweaking so I'm down with that if we want to test the actual speaker.Why wait? Why not just do a nearfield of the driver in the box right now and then pull the driver out of the box and do another one. Don't block the rear vent while it is out of the box though.

[toddalin]

No one perished anything that I am aware of.I suspect that most people are betting on the L200 box, not the driver.I said I would...
Why wait? Why not just do a nearfield of the driver in the box right now and then pull the driver out of the box and do another one. Don't block the rear vent while it is out of the box though.

Thanks. Appreciate it and look forward to your results.

Good idea. I guess when I pull the woofer out I could prop it up somehow and and run some pink noise through it.

[Doc Mark]

I've gotta pop the woofer out to pop the crossover back in after I finish tweaking so I'm down with that if we want to test the actual speaker. Any ideas on how testing should be performed? (We already have WT-2 results.) Maybe just put the thing up on a dolly and wheel it outside for testing. Maybe even down to the curb and...

Oh wait, Mark already did that with the L300s and ended up with some ??? replacements. :D

Hey, Todd,

Yep, I did that in an effort to save my hearing. But, the strafing noise that Regis tossed in, to keep folks away, dang near left me "deef"!! :blink::blink: You may remember that the person that originally "took" the L300's, and left those neat little RS Minimus 7's in their place, returned the 300's the next day. Sweet Bride carried them up to the house, and we have them, once again. You know, when I hooked up the 7's, biamped to that JBL 2242H, they worked pretty good, except that the poor old 18" JBL just couldn't keep up with those high performance Minimus 7's!!! ;);););)

Of course, all the above is absolute :bs: , but I couldn't help myself, and YOU started it, anyway! ;):D

This has been a very interesting thread, Todd, and I've enjoyed "seeing" what you are trying to fix in this system. Your trials and tribulations in all this have made for some very educational reading! Thanks for sharing it with us, and best of luck finally sussing it out! Take care, and God Bless!

Every Good Wish,
Doc

[toddalin]

Hey, Todd,


This has been a very interesting thread, Todd, and I've enjoyed "seeing" what you are trying to fix in this system. Your trials and tribulations in all this have made for some very educational reading! Thanks for sharing it with us, and best of luck finally sussing it out! Take care, and God Bless!

Every Good Wish,
Doc

As I recall, you have 2235's in those. I recognize that it is not an L200 cabinet, but is of similar shape and not too much larger. How's about you measure what yours are doing in your room?

On the other hand, this could be like an engine dynometer. More often than not, people are disappointed by the results for the level of work they did and what they thought they had.:drive:

BTW, the '64 goes on the dyno tomorrow. Its been a few years and it would be nice to see if my mods there paid off. But like all things, it won't be strictly comparable. It will be a different dyno under different weather conditions and they all read out a little differently. When you're looking at small changes, there can be too many other variables that obscure your results. :banghead:

[Doc Mark]

As I recall, you have 2235's in those. I recognize that it is not an L200 cabinet, but is of similar shape and not too much larger. How's about you measure what yours are doing in your room?

On the other hand, this could be like an engine dynometer. More often than not, people are disappointed by the results for the level of work they did and what they thought they had.:drive:

BTW, the '64 goes on the dyno tomorrow. Its been a few years and it would be nice to see if my mods there paid off. But like all things, it won't be strictly comparable. It will be a different dyno under different weather conditions and they all read out a little differently. When you're looking at small changes, there can be too many other variables that obscure your results. :banghead:

Evening, Todd,

You are right, our L300's have 2235H's in them, and I like that woofer quite a bit. If it would help you, or be of interest, I can dig out my AS-1000, and run some pink noise through our system, with the EQ set flat, and see how they look. Unfortunately, I have not yet replaced my old Rat Shack SPL meter, and I know that is not really up to your standards, but I can measure the SPL's too. But the display on the AS1000 will probably tell you what you want to know, and I'd be happy to do that for you. It would certainly be interesting to actually "see" what the L300's are doing here in our place! BTW, I have our EQ goosed up at around 32HZ, so that would make a difference, too.

If it were not so hard to carry those L300 behemoths up and down the stairs ('bout killed me getting them up here after we bought them from Regis!!:blink::blink:), I'd gladly bring them down to your place for some testing with you and Grumpy.

I also have those 4333 cabinets that Grumpy passed along to me, but they are still in need of attention, and I don't think they would be able to offer you what you need without a bit of work. They do have another pair of 2235H's in them, right now, however.

Last, but not least, I can bring that other set of 2235H's down to your place, and you can install them in your L200s, so you and Grumpy can "see" what difference that woofer might make in the same cabinet. I can bring the 4333's, too, if that would help you. I'd have to do some down and dirty hole plugging in the back, but that wouldn't matter too much, me thinks, as I have to fill and finish those holes anyway.

Let me know if any of this sounds interesting to you, and we can go from there. It would be fun, no matter which way we did it!

Best of luck on getting a clean bill of health on the '64!! I know you're a very Proud Papa!! Take care, and God Bless!

Every Good Wish,
Doc

[toddalin]

Evening, Todd,

You are right, our L300's have 2235H's in them, and I like that woofer quite a bit. If it would help you, or be of interest, I can dig out my AS-1000, and run some pink noise through our system, with the EQ set flat, and see how they look. BTW, I have our EQ goosed up at around 32HZ, so that would make a difference, too.

Let me know if any of this sounds interesting to you, and we can go from there. It would be fun, no matter which way we did it!

Best of luck on getting a clean bill of health on the '64!! I know you're a very Proud Papa!! Take care, and God Bless!

Every Good Wish,
Doc

Sound level is not of concern so you can leave the Rat Shack in its pack.

Would be nice to know what the freq response is doing though. Just leave all the eq turnd off. I would think that you would want to do this just to set your horn and tweeter levels for flattest response in your room anyway. That's how I set mine. Then I let the Yamaha eq the speakers to the room from there. The less processing the receiver does, the better because it has a limited number of bands it can process (31 I think) so it picks the worst offenders. ;)

If we get together for testing/BS, we'll let you know.

[grumpy]

testing/BS?

I'll guess about 1:2, even if we try to stay focused ;)

Can't help out this weekend, but I'll turn PM's back on...

[Ian Mackenzie]

Both the 4430 and 4435 as two ways have what I would call massive fill for a reflex enclosure compared to the vintage 43XX's.......just a tip.

[Doc Mark]

Sound level is not of concern so you can leave the Rat Shack in its pack.

Would be nice to know what the freq response is doing though. Just leave all the eq turnd off. I would think that you would want to do this just to set your horn and tweeter levels for flattest response in your room anyway. That's how I set mine. Then I let the Yamaha eq the speakers to the room from there. The less processing the receiver does, the better because it has a limited number of bands it can process (31 I think) so it picks the worst offenders. ;)

If we get together for testing/BS, we'll let you know.

Morning, Todd and Grumpy,

I do hope that we can all get together for a bit of testing and a lot of BS! That would be fun! I can bring any of the above, except the L300's, as they are just too heavy to carry down the stairs, and I don't want to take any chances of dinging up the enclosures.

Grumpy, I like your "testing to BS ratio", and think that's just about perfect!! ;):D

Todd, I will most certainly dig out the AS1000, and plug it into the system, to see what's going on. As a former musician, and after having spent a good many years surrounded by bass that knocks you out of your seat, I have found that, for my own tastes, almost ALL speaker systems need some bottom end boost from a good EQ. I want my music to sound as close to what I consider "real" as possible, and to my old ears, flat systems tend to be very bass-shy to me. Don't want "boom", just good, solid, bass which can rattle the room, when appropriate!

As for setting up the horn levels, as soon as we got the L300's up the stairs and hooked up to the system, we spent a few days listening to them, with a variety of different types of music. Both Sweet Bride and I thought that the horns levels were quite a bit too much of a good thing, as they were set. So, we adjusted the levels downwards until things sounded normal and natural, and for us that meant when the MF and HF had no sibilance or harshness, and when female voices and violins sounded as they should, sweet and clear with no edge to them. Now that we've enjoyed the L300's for a while, we are both very happy with their sweet, natural sound. In fact, we're even happy with their bass response, though Sweet Bride knows that I have to play with an 18" subwoofer, "just because"!! She's OK with that, which is a real blessing!

I hope that we can plan a fun day of testing/BS-ing, and look forward to that happening! Take care, and God Bless!

Every Good Wish,
Doc

[toddalin]

This evening I tried increasing the high pass on the horn from 16.41 to 20.71 mfd (had the three 4.3 mfd from before). That made a nice difference. It brings the male voice forward which was too laid back. It is now a little more "in your face." It's as if "and then the man steps right up to the microphone." It even gave Freddie Mercury some balls!

I had tried this with the H91 horn, but the difference was not as dramatic so the change was canned at the time. This works much better with the longer horn though. Have to see what the Behringer says about it, but I think it stays regardless. :applaud:

[Ian Mackenzie]

Can I make a suggestion.

I know its an outlay but if you insist on bring this up and messing with other diy ideas the http://www.woofertester.com/stproduct.htm is right up your alley. This thing will detect impediance resonances (that dip) and do a whole host of other neat stuff and appear user friendly.

Otherwise its all guess worth. I'd much rather the satisfaction of knowing I got it right particulary of I was going to post it publically

Just my 2 cents worth:).

No affiliation with this product but I think it would be money well spent for any diy person on these forums.

[mini]

Hi,

http://www.fesb.hr/~mateljan/arta/

Did You know that tool? It's quite professional in that it requires an already informed user. The manual should teach enough of the basics though. Its free. The demo-mode is fully functional but in saving raw data. Evaluated results may be exported to ascii-data files and as that imported to simulation programs.

I do not know exactly what this thread is about. The dip @ 600Hz could have a lot of reasons: box/room/mic interactions, internal resonance, raw woofer flaws, horn freq/ response, relative phase of the 2 speakers. 2 solve the problem the project should undergo an analytical evaluation: measuring ampl/ and phase! of each single driver, virtual reflection free measurements e/g ground plane && gating!, etc pp.

From that the issue should be treatened easily. After all the above mentioned software could help further on to fit the whole thing into a specific room. It offers a "dual gated" mode - read Yourself, what the manu claims it to be for.

Jurgen

[Beowulf57]

Morning, Todd and Grumpy,

"I have found that, for my own tastes, almost ALL speaker systems need some bottom end boost from a good EQ. I want my music to sound as close to what I consider "real" as possible, and to my old ears, flat systems tend to be very bass-shy to me. Don't want "boom", just good, solid, bass which can rattle the room, when appropriate!

As for setting up the horn levels,...Both Sweet Bride and I thought that the horns levels were quite a bit too much of a good thing, as they were set. So, we adjusted the levels downwards until things sounded normal and natural, and for us that meant when the MF and HF had no sibilance or harshness, and when female voices and violins sounded as they should, sweet and clear with no edge to them."

Every Good Wish,
Doc

Wow! A man after my own ears :applaud:.

[Beowulf57]

This evening I tried increasing the high pass on the horn from 16.41 to 20.71 mfd (had the three 4.3 mfd from before). That made a nice difference. It brings the male voice forward which was too laid back. It is now a little more "in your face." It's as if "and then the man steps right up to the microphone." It even gave Freddie Mercury some balls!

I had tried this with the H91 horn, but the difference was not as dramatic so the change was canned at the time. This works much better with the longer horn though. Have to see what the Behringer says about it, but I think it stays regardless. :applaud:

Ah so...dropping the crossover point brings the horn into play lower down and ameliorates the problem. Where is that crossover point sitting now? 700Hz or so?

[Doc Mark]

Wow! A man after my own ears :applaud:.

Hi, Beowulf57,

Cool! I can only judge what sounds "natural", by my own years of playing professional music. If it doesn't sound like it did up on stage, then it doesn't sound "right" to me. Others will most certainly have different criteria, and that's as it should be. But, speaking only for myself, most of the time when I hear a system that is supposed to be "flat", that's exactly how it sounds to me "FLAT"!! No life, not natural, and almost, dare I say it, "cheap". :(:blink: But, hey, each to his/her own, eh?!! Long may it be so!! Thanks for your shout back, and God Bless!

Every Good Wish,
Doc

[toddalin]

Ah so...dropping the crossover point brings the horn into play lower down and ameliorates the problem. Where is that crossover point sitting now? 700Hz or so?

Don't know as I don't have the crossover modeling program. But, this is the configuration as it currently stands. Maybe someone here could model it.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Revised_Crossover.jpg

Next step is to trade out the 2.5 mfd low pass on the mids to either a 2.0 mfd, or take it back to 1.5 mfd and try changing the tweeter from 1.5 mfd to 1.0 mfd.

These were originally each 1.5 mfd (ala N7000 and N8000), but I felt this to be a little too "spitty." Changing the horn low pass to 2.5 mfd took out a little too much in this range leaving a small dip.

I recognize that taking the LE175 on the H92 this low may be a little out of range for the horn/driver, but it is giving me more clarity in the vocal range where my hearing is sensitive that I'm just not getting out of the woofer.

[toddalin]

Hi, Beowulf57,

Cool! I can only judge what sounds "natural", by my own years of playing professional music. If it doesn't sound like it did up on stage, then it doesn't sound "right" to me. Others will most certainly have different criteria, and that's as it should be. But, speaking only for myself, most of the time when I hear a system that is supposed to be "flat", that's exactly how it sounds to me "FLAT"!! No life, not natural, and almost, dare I say it, "cheap". :(:blink: But, hey, each to his/her own, eh?!! Long may it be so!! Thanks for your shout back, and God Bless!

Every Good Wish,
Doc

I don't listen to them "flat" either. But I do all my testing with them set flat. (Except when I forget to turn off the processing then recognize this error an hour later and redo everything again. ;) )

[Ian Mackenzie]

I've got news for ya, you've got your crossover completely up the shit.

Assuming you have the longer horn in there there are multiple problems and hence you are attempting to compensate here and there.

Below is a comparison of your last iteration versus the equivalent 4333 network. The zobel on the woofer is not trival, here is the action of the horn bandpass filter. Same for the 2405

The top curves are voltage drivers comparing your last iteration with the equivalent as abaseline. Then the equivalent for clarity and lastly the comparions of messing with LP / zobel and the high pass leg of the horn band pass.

I have not shown the phase relationships and the summing of the on axis response on the baffle as this will only serve to confuse the issue at this stage. Other than to say in terms of voltage drive less is actually more when the path lengths of the woofer to the horn are taken into account while the equivalent has a softer roll of at lower frequencies.

I recommend you build the equivalent an stuff some fibreglass in to the rear of the enclosure.

[toddalin]

I've got news for ya, you've got your crossover completely up the shit.

Assuming you have the longer horn in there there are multiple problems and hence you are attempting to compensate here and there.

Below is a comparison of your last iteration versus the equivalent 4333 network. The zobel on the woofer is not trival, here is the action of the horn bandpass filter. Same for the 2405

The top curves are voltage drivers comparing your last iteration with the equivalent as abaseline. Then the equivalent for clarity and lastly the comparions of messing with LP / zobel and the high pass leg of the horn band pass.

I have not shown the phase relationships and the summing of the on axis response on the baffle as this will only serve to confuse the issue at this stage. Other than to say in terms of voltage drive less is actually more when the path lengths of the woofer to the horn are taken into account while the equivalent has a softer roll of at lower frequencies.

I recommend you build the equivalent an stuff some fibreglass in to the rear of the enclosure.

Thanks Ian.

It actually looks like the crossover mods are acomplishing their goals. Recognize that that equivelent crossover was designed for a 2231 and not a 2235 equivelent. I'm fighting a frequency dip in the overall response, and the bump in the low end of the horn is working to that end as you've illustrated. Maybe 20.7 mfd is a bit much, but it gets me in the right direction. I note the equivelent circuit uses 18 mfd whereas the L200B (and many other varients) use 16.5 mfd as I had done. Maybe I'll try the horns with that range of capacitance.

The woofer network is based on the L200B but that used a 30 mfd on the Zobal and this was changed to 15 mfd to bring the woofer up some. It did pay sonic benefit. Stuffing the cabinet paid far less benefit.

Maybe in an ideal world in the right cabinet with the 2231 and 077, the equivelent circuit would be ideal. But with the 2235 equivelents I have, in the L200 cabinet I have, in my room, under my conditions, etc., it's not letting the woofer sing high enough.

As someone on this board is fond of saying, "This stuff is all about compromises." I'm trying to compromise the crossover to compensate for what would appear to be an aberrent woofer behavior. (Go back and look at the spectrum of just the 2235 woofer equivelent in this cabinet in the room with no crossover.) Obviously the equivelent circuit does not expect such aberrent behavior.

Thanks again.

[Ian Mackenzie]

Hi Todd,

Below are the target response curves normalised for levels.

As I said earlier the only way to determine of the woofer is at fault is to put it on a large flat baffle and measure it facing upwards in an open space

The dip you are seeing is around 5 db if I recall correctly. But this is only one measurement at one place.

The aspect of the actual transition from the horn to the woofer is complex.

But what we are looking for is 12 target acoustic slopes for your drivers. The crosover points as such are modified to allow for phase shifts as a result of the horn path length and as I recall the woofer and horn are in phase.

Why is this done. So that in the vertical plane you get an even coverage at the crossover point. Otherwise it would sound horrible.

If you adjusted the mic for measurements at intervals of varying height the response around the crossover point will change considerably.

The JBL engineered crossover is designed to offer the smoothest off and on axis summming.

Unless you have years of experience and powered simulators its like finding a needle in a hay stack and mere adjustments just compound the issues.

In summary by process of elimination the "visual" woofer response can easily be determined by measuring it on a large baffle pointed upwards.

It will be a yes / no outcome.

I would suggest it partly the box )stuff in some fibreglass) but what you are subjectively hearing is all the other issues in terms of the balance of the overall system not what is happening at one metre with one static measurement.

[Doc Mark]

Hey, Guys,

I have what might be a very stupid question about all this, but I'll ask it, anyway, as I'm "stupid" about much of this. Todd, would it help you, at all, for me to bring my Ashly XR-4001 electronic crossover, and a few spare amps, down to your place? I was wondering, if you got rid of all the passive crossovers completely, and just tested with the woofers were doing in your L200 enclosures, would that help clear away some of the questions about this, or just add more "don't know's" to the mix? I look forward to hearing what you, Ian, and all have to say about this. Seems to me that, if you were just wanting to see how the woofer is performing in your enclosure at various crossover frequencies, doing it electronically would cut through some of the questions about this. If it WOULD be of benefit, I'll be happy to bring that down so you could play with it. Take care, and God Bless!

Every Good Wish,
Doc (ignorant, but hoping to learn....)

[toddalin]

Hi Todd,

Below are the target response curves normalised for levels.

As I said earlier the only way to determine of the woofer is at fault is to put it on a large flat baffle and measure it facing upwards in an open space

The dip you are seeing is around 5 db if I recall correctly. But this is only one measurement at one place.

The aspect of the actual transition from the horn to the woofer is complex.

But what we are looking for is 12 target acoustic slopes for your drivers. The crosover points as such are modified to allow for phase shifts as a result of the horn path length and as I recall the woofer and horn are in phase.

Why is this done. So that in the vertical plane you get an even coverage at the crossover point. Otherwise it would sound horrible.

If you adjusted the mic for measurements at intervals of varying height the response around the crossover point will change considerably.

The JBL engineered crossover is designed to offer the smoothest off and on axis summming.

Unless you have years of experience and powered simulators its like finding a needle in a hay stack and mere adjustments just compound the issues.

In summary by process of elimination the "visual" woofer response can easily be determined by measuring it on a large baffle pointed upwards.

It will be a yes / no outcome.

I would suggest it partly the box )stuff in some fibreglass) but what you are subjectively hearing is all the other issues in terms of the balance of the overall system not what is happening at one metre with one static measurement.

Two meters.

But the anomoly is present pretty much where ever I measure at varying distances and heights in normal positions in the room, (with the exception of such things as lying the microphone on the floor).

And I'm not the only one who hears it. Grumpy also picked up on it.

To me the best way to describe it is as if someone is to far from the microphone. That "up-front" personal quality is missing and it takes away from intelligibility.

Another way to think of it is as if someone lowers their voice. When you speak in quiet tones, almost to a whisper, you get an "airy" sound and loose the up-front personal quality associated with that region of the midrange that give vocals (and brass, etc.) that "forward" sound. Bugs me!

Regardless of what the woofer can or can't do on a big flat surface, I can only surmize what those particular woofers are doing in those cabinets in that room. My only tools include my ears, my Behringer, and a sound level meter. I can tell visually on the Behringer and/or sonically with my ears when a change works to the benefit.

Even if there is a physical problem with the woofers in the way that they were reconed be it parts/vendor/labor/??? or not, I'm pretty much stuck with them in these boxes in this room in this situation. I really don't want to invest another ~$250 to have a woofer reconed to find it does the same thing (or $750 for three if it does make some difference for better or for worse just so they are all the same).

While JBL convention may work in those cases that it was designed for, apparently it can be off in others if parameters fall outside the norm. In these cases, some tweaking could pay sonic benefit.

[toddalin]

Hey, Guys,

I have what might be a very stupid question about all this, but I'll ask it, anyway, as I'm "stupid" about much of this. Todd, would it help you, at all, for me to bring my Ashly XR-4001 electronic crossover, and a few spare amps, down to your place? I was wondering, if you got rid of all the passive crossovers completely, and just tested with the woofers were doing in your L200 enclosures, would that help clear away some of the questions about this, or just add more "don't know's" to the mix? I look forward to hearing what you, Ian, and all have to say about this. Seems to me that, if you were just wanting to see how the woofer is performing in your enclosure at various crossover frequencies, doing it electronically would cut through some of the questions about this. If it WOULD be of benefit, I'll be happy to bring that down so you could play with it. Take care, and God Bless!

Every Good Wish,
Doc (ignorant, but hoping to learn....)

Thanks for the offer. We did find out what the woofer was doing in the box all by itself without the crossover. See the included picture.

The cursor is sitting at 800 hz. Obviously crossing the woofers over at 800 Hz doesn't do much good if it is not even getting there. "If you can't raise the bridge, lower the river."

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Woofer_Without_Crossover.jpg

But that doesn't preclude getting together for some testing/listening. Even when the cabinets are buttoned up, you can still access the components at the back.

Maybe Grumpy/Bart would like to come down after these fires cease.

Thanks.

[Ian Mackenzie]

I think you are taking my post the wrong way or missing the point.

Yes there is a problem , that is obvious.

But what is the problem and how to fix it.

I very much doubt it is a fault with the woofer. Its probably something really dumb.

The point of talking it out of the box is to eliminated any internal reflections / cancellations or baffle diffraction that the box "might be causing.

If it is the woofer then its a case of deciding some alternative course of action.

Sometimes woofers with foam surrounds have resonances but I have never seen this with (4) 2235H I have used.

If its an after market refoam to recone then this is a possibility. (There are usually mutiple peaks and dips if the surroud or spider have resonances)

A large baffle ie a sheet of mfd called am IEC baffle will resolve this.
Run an imediance curve and measure the response.

If its good then you know the problem is the box or something else.

You can then test the box by stuffing more "fill" and measure it.

[Zilch]

http://audioheritage.org/vbulletin/showthread.php?t=9221

[toddalin]

I think you are taking my post the wrong way or missing the point.

Yes there is a problem , that is obvious.

But what is the problem and how to fix it.

I very much doubt it is a fault with the woofer. Its probably something really dumb.

The point of talking it out of the box is to eliminated any internal reflections / cancellations or baffle diffraction that the box "might be causing.

If it is the woofer then its a case of deciding some alternative course of action.

Sometimes woofers with foam surrounds have resonances but I have never seen this with (4) 2235H I have used.

If its an after market refoam to recone then this is a possibility. (There are usually mutiple peaks and dips if the surroud or spider have resonances)

A large baffle ie a sheet of mfd called am IEC baffle will resolve this.
Run an imediance curve and measure the response.

If its good then you know the problem is the box or something else.

You can then test the box by stuffing more "fill" and measure it.

Thanks. We'll see what we can come up with.

[toddalin]

http://audioheritage.org/vbulletin/showthread.php?t=9221


Thanks Zilch for that reminder. These were your tests and they look pretty similar to mine, but because you used a 30 dB scale and I used a 15 dB scale, they just don't look as extreme.

http://audioheritage.org/vbulletin/attachment.php?attachmentid=12823&stc=1&d=1139280962

http://audioheritage.org/vbulletin/attachment.php?attachmentid=12825&stc=1&d=1139285046

[Beowulf57]

I recognize that taking the LE175 on the H92 this low may be a little out of range for the horn/driver, but it is giving me more clarity in the vocal range where my hearing is sensitive that I'm just not getting out of the woofer.

Yes, it may be a little out of range for the LE175/H92, just as is the case with my LE85/H92 crossed over at 500Hz...nevertheless, it works for me at any SPL's I like. If you like what you're hearing...:applaud:

As we know, distortion increases with level and originally, the LE85 (as with the LE175) was derated to 10 watts if used with a 500Hz crossover. As a simple test, hook up a digital meter in AC Min/Max/Average recording mode (I use the Fluke 85 DMM which is good to 20KHz or the Fluke 99 Scopemeter which is good to 50 KHz) to the LE175 terminals while playing programme material as loud as you ever listen. Then check the maximum and average voltage across the driver: when I last did this, the maximum was around 4 volts and the average was far lower. So at most I was driving the LE85's to 2 watts or less...perhaps that's why I don't hear any problems running the driver/horn combo lower than recommended:dont-know.

[Ian Mackenzie]

Tunnel Audio

I was just glancing at the build thread. Holy Bat Tunnel!

You should be locked up in the tower and chained to a Bose Lifestyle blaster for 30 days and 30 nights!!

Can I Pay Pal you some money to build a correctly designed enclosure?

Assuming this is the inset baffle then you have measured then without doubt the numbers strongly point to this as your major contributing issue. The first thing I would do is run a circular saw around that miserable insert a get rid of 4-7 inches down near the woofer period.

As I recall this style of freakin box was used with a different driver and what happened is any ones guess.

[Doc Mark]

Morning, All,

Ian, you bring up a good point, and one about which I've often wondered. With the L300's, and a few other such cabinets, isn't there bound to be a big diffraction problem with those edges projecting so far from the baffle? Back when I built my first large system, I used the 8ft3 design that JBL offered in their set of JBL enclosure plans. On that one, the top and bottom edges of the cabinets stuck out a good bit, about as far as the entire edge of the L200's. I was always worried about tweeter diffraction problems with that system, and even though I did love the way it sounded, I was always tempted to take a saw and remove both the top and bottom edges of those boxes! In fact, at a later time, just before I sold them to a friend, I did just that. He loved them, and for all I know, still uses them in his system.

I'd be interested in what others think about those edges sticking out so far from the baffles on the L200's. Take care, and God Bless!

Every Good Wish,
Doc

[Beowulf57]

From a JBL installation monograph for components such as the LE20, LE30, 075, 375, LE85, LE175:

"Mounting the HL91 or 93...The angle of dispersion is so wide that some sound is radiated from the end of the lens. To prevent this sound from being reflected, the grille should wrap around the enclosure so that the lens is unobstructed on both sides as well as in front. If the sides of the cabinet must be completely solid, a wedge of glass wool should be inserted on either side of the lens, running the full height of the enclosure." (bold italics mine)

This is referenced to the S7 and S8 systems using the LE15A bass driver. Mind you, an accompanying drawing references this recommendation as, "Fiber glass wedge 6" in height to fill corners of enclosure."

In any case, why not try some wedges down the sides and along the bottom of that cabinet? :idea:

[toddalin]

From a JBL installation monograph for components such as the LE20, LE30, 075, 375, LE85, LE175:

"Mounting the HL91 or 93...The angle of dispersion is so wide that some sound is radiated from the end of the lens. To prevent this sound from being reflected, the grille should wrap around the enclosure so that the lens is unobstructed on both sides as well as in front. If the sides of the cabinet must be completely solid, a wedge of glass wool should be inserted on either side of the lens, running the full height of the enclosure." (bold italics mine)

This is referenced to the S7 and S8 systems using the LE15A bass driver. Mind you, an accompanying drawing references this recommendation as, "Fiber glass wedge 6" in height to fill corners of enclosure."

In any case, why not try some wedges down the sides and along the bottom of that cabinet? :idea:

This is why the L200 cabinets have the grill inserts built into the sides along the slant plate.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/speaker1.jpg

Might be a good idea to try some wedges around the woofer too. ;) I'll have to see what I can find to try there.

[Ian Mackenzie]

Morning, All,

Ian, you bring up a good point, and one about which I've often wondered. With the L300's, and a few other such cabinets, isn't there bound to be a big diffraction problem with those edges projecting so far from the baffle? Back when I built my first large system, I used the 8ft3 design that JBL offered in their set of JBL enclosure plans. On that one, the top and bottom edges of the cabinets stuck out a good bit, about as far as the entire edge of the L200's. I was always worried about tweeter diffraction problems with that system, and even though I did love the way it sounded, I was always tempted to take a saw and remove both the top and bottom edges of those boxes! In fact, at a later time, just before I sold them to a friend, I did just that. He loved them, and for all I know, still uses them in his system.

I'd be interested in what others think about those edges sticking out so far from the baffles on the L200's. Take care, and God Bless!

Every Good Wish,
Doc

The horn is a different sort of issue in terms of diffraction at higher wave lengths.

At lower frequencies it will occurr at 1/2 wave length of the distance from the centre of the cone back to the bottom and back to the centre of the cone. The effect is typically cancellation at a particular frequency, if more than one direction is involved then there will be not just a dip but a notch

Depending on the profile and the properties of the dust cap of the woofer the radiation angle of the cone drops off wth in increasing frequency and is typically 100 degrees at 1000 hertz, ie 50 degress off axis.

So higher up in frequency there is less likely to such issues and the woofer response is attenuated by the crossover network.

Some woofers are smooth, some have a peaky response from 400 hertz up and some increase amplitude sharply with frequency above 400 hertz. Its a case of what happens when you put a given woofer in a given box

Box styles changed over time as can be seen below. I dont think this is anything to loose sleep over. I mean these systems are that old who cares.

http://www.lansingheritage.org/images/jbl/specs/pro-comp/2205/page2.jpg
http://www.lansingheritage.org/images/jbl/specs/pro-comp/2215/page2.jpg
http://www.lansingheritage.org/images/jbl/specs/pro-comp/2220/page2.jpg
http://www.lansingheritage.org/images/jbl/specs/pro-comp/2231/page2.jpg
http://www.lansingheritage.org/images/jbl/specs/pro-comp/2235/page2.jpg
http://www.lansingheritage.org/images/jbl/catalogs/1978-pro/page04.jpg

http://www.lansingheritage.org/images/jbl/specs/pro-speakers/1977-4331-4333/page2.jpg

http://www.lansingheritage.org/images/jbl/catalogs/1979-home/page3.jpg
http://www.lansingheritage.org/html/jbl/specs/home-speakers/1975-l300.htm
http://www.lansingheritage.org/images/jbl/catalogs/1971-home/page10.jpg
http://www.lansingheritage.org/html/jbl/specs/home-speakers/1975-l200b.htm

[Beowulf57]

This is why the L200 cabinets have the grill inserts built into the sides along the slant plate.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/speaker1.jpg

Might be a good idea to try some wedges around the woofer too. ;) I'll have to see what I can find to try there.

Cool! Also, the frame of the front grille might still be affecting the response as those side grille inserts do not extend all the way to the front. :hmm:

[Zilch]

O.K., DON'T read it, then.... ;)

http://audioheritage.org/vbulletin/attachment.php?attachmentid=12860&stc=1&d=1139359095

[BMWCCA]

O.K., DON'T read it, then.... ;)
I did. Wow. This isn't your first rodeo on this subject, is it? Seems like you guys beat this horse dead almost three years ago. Carry on. I always love a good train wreck! :applaud:

[Ian Mackenzie]

I think you would need at least 3 inch of studio acoustic foam at those frequencies for an appreciable difference.

(If you have not got a circular saw you know what to ask for Xmas)

[toddalin]

O.K., DON'T read it, then.... ;)

http://audioheritage.org/vbulletin/attachment.php?attachmentid=12860&stc=1&d=1139359095

Yes, I reread it. And yes, I/we've been chasing this problem for almost 3 years now. And yes, it seems like nothing we have done has ameliorated it. And yes, it still bugs the heck out of me. :banghead:

[hjames]

Cool! Also, the frame of the front grille might still be affecting the response as those side grille inserts do not extend all the way to the front. :hmm:

Okay - I pulled this picture from an old thread about 2 years ago and its intrigued me ever since - anyone know anything about this project?

forget the upgrade to 4way action, its the relocated front baffle that interested me!

Wouldn't THAT resolve the problem?

[toddalin]

Okay - I pulled this picture from an old thread about 2 years ago and its intrigued me ever since - anyone know anything about this project?

forget the upgrade to 4way action, its the relocated front baffle that interested me!

Wouldn't THAT resolve the problem?

As I recall, the intent there was to provide space for the H92. But the 8" kind of defeats the requirement for the long horn. The additional internal volume does leave room for a sub-enclosure for the 8" without changing that for the 15" drastically.

I think if you go back and look at Zilch's work and his overstuffed front baffles, if I'm reading his work correctly (Zilch?) (it's a long thread) you will see the problem persists. If it was a matter of edge reflection/cancelation, wouldn't all that fiberglass have cured or at least changed it?

Heather, do you have the equipment to see if your L200 cabinets are also showing this dip?

[pos]

Wow, very impressive L200 mod, thank you heather!
That was something I was thinking about with mine, but had I never seen this picture!

I did remove the overhangs on mine, and here is what I found, all around the front baffle (1st attached picture). Poor construction...
I had to add a new baffle on top of the old one.

I think these box also really needs bracing. Front-back bracing is difficult because of the angle of the front baffle.

[hjames]

Again, those aren't mine - just an interesting photo I saved of someone else's project.

I don't have access to any spectrum analyzers - I have a cheap RS Sound pressure meter and thats about it.
'Course our "L-200s" have the 2234s, short horns, 2405 slots, plus the Giskard designed 3133 crossovers - the boxes were just handy and an improvement over the 4320s I started with.





Heather, do you have the equipment to see if your L200 cabinets are also showing this dip?

[toddalin]

Again, those aren't mine - just an interesting photo I saved of someone else's project.

I don't have access to any spectrum analyzers - I have a cheap RS Sound pressure meter and thats about it.
'Course our "L-200s" have the 2234s, short horns, 2405 slots, plus the Giskard designed 3133 crossovers - the boxes were just handy and an improvement over the 4320s I started with.


Thanks. The xover/horn/tweeter are not so much an issue as the box/woofer relationship as the anomoly occurs well below the crossover frequency and I think you are also crossing over at about 800 Hz.

It would be "very interesting" to see what the 2234 is doing in the L200 box.

[4313B]

I did. Wow. This isn't your first rodeo on this subject, is it? Seems like you guys beat this horse dead almost three years ago. Carry on. I always love a good train wreck! :applaud:This project is literally a one post project. Bolt 2235H, HL91/92/93/LE175/LE85/375/376, 077 and LX300 into modified box and post a couple of pictures. Maybe include a sentence detailing a conjugate modification for the 2235H in place of the 2231H (The LX300 worked with the 124A/H, 2203A/H, LE14A/H, 136A/H, 2231A/H. They all used the same voice coil meaning that Re and Le was the same.) I think we have four different threads and hundreds of posts.
It would be "very interesting" to see what the 2234 is doing in the L200 box.To what end?

I did remove the overhangs on mine, and here is what I found, all around the front baffle (1st attached picture). Poor construction...
I had to add a new baffle on top of the old one.

I think these box also really needs bracing. Front-back bracing is difficult because of the angle of the front baffle.Yeah, as I said, Greg couldn't remember if the L200 box was one of the "problem" boxes. It could need a panel or two tied together or some kind of internal partial barrier created to break up a node. The recessed baffle is pretty bad, nice modification.

[toddalin]

To what end?


To the end that if this showed substantial improvement, I would pull the 2235s and have their dust caps replaced with those without mass rings.

[4313B]

I suppose it is possible for you to remove the mass rings, perhaps with MEK, without damaging the coils/formers but you might be looking at recones instead. I personally wouldn't put that kind of money into alnico baskets.

If it is a box issue how is a different woofer going to change anything?

Why don't you put some W15GTi's in these boxes?

[1audiohack]

If it is an enclosure driven problem such as a panel resonance, internal or external reflection, or a vent "pipe organ" resonance it will show up as a notch or bump in a high resolution impeadance sweep.

[grumpy]

yep. a better, higher resolution sweep could be redone.

re 2234... I have one if you're -really- interested in trying one out, Todd...
but I've measured 2235 vs 2234 in the 4330 cab... other then the bottom
end, the 2334 plot almost lays right on top of the 2335 plot (if you add ~3dB
to the 2335 plot). E.g., I wouldn't expect an improvement.

[toddalin]

yep. a better, higher resolution sweep could be redone.

re 2234... I have one if you're -really- interested in trying one out, Todd...
but I've measured 2235 vs 2234 in the 4330 cab... other then the bottom
end, the 2334 plot almost lays right on top of the 2335 plot (if you add ~3dB
to the 2335 plot). E.g., I wouldn't expect an improvement.


Thanks for the offer. I'll give it some thought.

[toddalin]

I suppose it is possible for you to remove the mass rings, perhaps with MEK, without damaging the coils/formers but you might be looking at recones instead. I personally wouldn't put that kind of money into alnico baskets.

If it is a box issue how is a different woofer going to change anything?

Why don't you put some W15GTi's in these boxes?

You're assuming that it is purely a box issue as opposed to a woofer/box issue. I'm not so convinced.

Don't think I hadn't thought about it. But I really didn't want to lay another $750-$1K into woofers after recently doing so.

And if it wasn't such a pain to do, don't think I hadn't thought about trying my W15GTI in that cabinet. But that's a 2-person job. I guess I could put an original LE15B in there and see what it does. (I have a couple doing nothing.) Wasn't that actually the original speaker in that cabinet?

[Robh3606]

Wasn't that actually the original speaker in that cabinet?

Yes it was. Crossed over at what 1.2k?.

Rob:)

[4313B]

You're assuming that it is purely a box issue as opposed to a woofer/box issue. I'm not so convinced.I'm not assuming anything since I have no access to the boxes or drivers but I know I'd have figured it out pretty damn quick if I did have access. I have zero tolerance for perpetual problems.

[toddalin]

I'm not assuming anything since I have no access to the boxes or drivers but I know I'd have figured it out pretty damn quick if I did have access. I have zero tolerance for perpetual problems.

Or perhaps, the dip wouldn't have offended your sensibilities, and you would have called it "good" from the "git go" and just Let It Be a couple years back. But having no access to the boxes or drivers, I guess we'll never know. :dont-know

I would assume that this is what other people have done when they put 2235 equivelents into L200 boxes.

[4313B]

Or perhaps, the dip wouldn't have offended your sensibilities, and you would have called it "good" from the "git go" and just Let It Be a couple years back. But having no access to the boxes or drivers, I guess we'll never know. :dont-knowThe dip would have shown up immediately during the prototype process and I would have investigated it.

You're mostly concerned with ignoring any kind of advice and blogging away through four different threads about the same old tired bullshit. You probably need to dump the pile of junk and buy some loudspeakers off a showroom floor somewhere. I know several others have tried to help you and ended up tossing their hands in the air. I can empathize with that strategy. Best of luck to you.

[toddalin]

The dip would have shown up immediately during the prototype process and I would have investigated it.

You're mostly concerned with ignoring any kind of advice and blogging away through four different threads about the same old tired bullshit. You probably need to dump the pile of junk and buy some loudspeakers off a showroom floor somewhere. I know several others have tried to help you and ended up tossing their hands in the air. I can empathize with that strategy. Best of luck to you.

Right.

And none of the advise that I've seen has gotten me closer to removing the dip short of changing out the cabinets, the woofers, or both.

And, I have tried most of the ideas bantered about including overstuffing the box, bracing, styrofoam at the sides of the woofers, none of which did anything significant. (Sorry if I'm really not too keen on cutting away the 3" overhang to the sides of the woofer just to see it it has a positive effect.)

Testing for the sake of testing (such as putting the woofer on a 4x4 sheet of wood) may prove interesting and may even show the woofer to be linear, it doesn't solve the problem.

I think that Majestik has the right idea. If adding a capacitor to the crossover improves the sound, so be it and put it in if it works toward solving the problem even if unconventional.

But thanks anyway.

[Beowulf57]

If it is an enclosure driven problem such as a panel resonance, internal or external reflection, or a vent "pipe organ" resonance it will show up as a notch or bump in a high resolution impeadance sweep.

Panel resonance? What panel resonance?! I love home brew tests...how about trying some mass loading of the panels (bag of cement, or sand on top; large box clamps with a 2x4 on each side of the cabinet, or front to back to test the baffle) and then test that response once again? If it is a panel resonance, you ought to see some reduction of the problem.

Also, is that baffle board 3/4" or 1" plywood or particle board?

[Zilch]

I did the highres impedance sweep. There were no apparent resonances, rather, flattened areas:

http://audioheritage.org/vbulletin/attachment.php?attachmentid=12863&stc=1&d=1139361414

Regarding the fiberglass, I concluded that it didn't do much, i.e., to whatever the source, it was transparent.

In the end, I concluded it was a measurement artifact, that I had well exceed my level of competence, and moved on.

Jackgiff has the same 2235H/L200 setup, and the Behringer RTA. PM him and ask if he'll do a measurement.

Yeah, I still have them, too, but there's no method for obtaining reliable data in this frequency region other than groundplane; not an option here, alas.... :blink:

[Robh3606]

Well lets really confuse things. Here's what I got at 1 meter and close in at 1" with a 2235 in one of my 4344 enclosures. First 2 are 1 meter at 1/12 and 1/3 last is 1/12 at 1" These are ungated so keep that in mind they include the room. I tried Sine and it was a mess with measurement issues.

Rob:)

[grumpy]

FWIW, if you decide to spend more time on this, I have a contact "mic" that
might help to identify unusual -panel- resonances.

-Something- is producing a fairly narrow-band antiphase excitation in the
bandpass of the woofer... room, cabinet, inset baffle airspace. Need to
separate the candidates. I'm (personally) convinced it's not the driver.

I frankly can't imagine putting foam/fiberglass on either side of the woofer
(on the baffle) should have been expected do much/any good.

A -hard- surface, approximating the posted cab-forward "fix" might help
-if- that inset baffle is the culprit. 2" of cardboard with a 15" diameter
cutout might temporarily suffice for testing. A more elegant solution could
then be implemented if warranted.

[Ian Mackenzie]

That region is very difficult to measure with any reliability.

When I set up my 4345 anything within a 1 metre radias of the front baffle influenced the measurements.

These days I use 6 inch thick slabs of acoustic grade foam to minimise room influences on measurements

[toddalin]

Did some tweaks and some more measurements. It ain't reflection off the cabinet "lips."

This first picture shows the near field as requested by Ian. The microphone was placed <1/2" from the woofer dome. This is the woofer connected straight to the amp with no crossover. Look familiar?

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/NF_No_xover.jpg

OK, this one shows the Mid high pass filter with the 16.4 mfd. Note how rough the slope is to the left of ~2.5K.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/164_mfd.jpg

This one shows the effect of increasing this value to 20.7 creating the "hump" in Ians plot. Note that the 900 Hz is also raised, but is still no higher than the other peaks. On the other hand, the surrounding values are also raised flattening out the slope somewhat. Also note that the 800 Hz has come up 2+ dB and is now comparable to the woofer, before it fell off the cliff. Note how in the prior picture, the 800 Hz was considerably lower than the woofer before it fell off the cliff. The next two lower bands also came up minimally. My ear picks up on this range and to me, this second picture sounds more clear and natural.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/207_mfd.jpg

[Ian Mackenzie]

Please undertand what you have posted above may make perfect sense to you in your living room but we are looking at this through what could be interpreted as a drinking straw in this thread.

In reference to the phase does it look familair I guess so.

I dont see anything conclusive about that post at all frankly.

Nothing is documented on how you did the measurements and they are very difficult to read.

Are your measurements time gated at 2 inches from the dust cap and what form of boundary layer insulation did you use to stop any for of reflection of the sides of the insert?

Your peristance is commendable but I dont think you have an awareness or understanding of some fundermental aspects of what has been raised by way of assistance.

[toddalin]

Please undertand what you have posted above may make perfect sense to you in your living room but we are looking at this through what could be interpreted as a drinking straw in this thread.

In reference to the phase does it look familair I guess so.

I dont see anything conclusive about that post at all frankly.

Nothing is documented on how you did the measurements and they are very difficult to read.

Are your measurements time gated at 2 inches from the dust cap and what form of boundary layer insulation did you use to stop any for of reflection of the sides of the insert?

Your peristance is commendable but I dont think you have an awareness or understanding of some fundermental aspects of what has been raised by way of assistance.

My near field measurement was taken on the Behringer at a distance of 1/2" from the woofer dome. (I don't know where you got 2 inches.) The microphone was simply placed at the dome, pink noise played, and the reading allowed to come to an average. I don't think the cabinet lips provided much in the way of boundary effects with the mic so far into the cone. The other two pictures were taken in the reference spot noted earlier in the thread, 78" from the grill and 32" from the floor.

"Look familiar" refers to the fact that the curve is similar to what I've measured at 2 meters (and at 1 meter, and elsewhere in the room, and with the crossover and without the crossover, and with the speaker tilted forward and backward and with styrofoam packed at the woofer sides, and on, and on, and on.

I'm sorry but this keeps bringing back to the conclusion that this is a characteristic of the woofer.

Is that a 2235 in your Avatar? If so, how about providing us with a measurement of it in that cabinet?

Thanks for your input.

[Mr. Widget]

Yes, I reread it. And yes, I/we've been chasing this problem for almost 3 years now. And yes, it seems like nothing we have done has ameliorated it. And yes, it still bugs the heck out of me. :banghead:I am sorry to butt in but I have glanced over the thread a couple of times and can't seem to find the post that states what the "it" is that seems to be the problem... or symptom.


Widget

[Robh3606]

"it"

The 2235's don't work the way they should looking at a 4430 frequency response plot.

http://www.lansingheritage.org/images/jbl/specs/pro-speakers/1984-4430-35/page05.jpg

There are drop outs/ notches in the response. When I was trying to do sine measurements I could get them buy moving the microphone, made the notches move and they didn't agree with the MLS measurements with the microphone in the same position. They were obviously measurement issues when I tried it.

Rob:)

[Ian Mackenzie]

My near field measurement was taken on the Behringer at a distance of 1/2" from the woofer dome. (I don't know where you got 2 inches.) The microphone was simply placed at the dome, pink noise played, and the reading allowed to come to an average. I don't think the cabinet lips provided much in the way of boundary effects with the mic so far into the cone. The other two pictures were taken in the reference spot noted earlier in the thread, 78" from the grill and 32" from the floor.

"Look familiar" refers to the fact that the curve is similar to what I've measured at 2 meters (and at 1 meter, and elsewhere in the room, and with the crossover and without the crossover, and with the speaker tilted forward and backward and with styrofoam packed at the woofer sides, and on, and on, and on.

I'm sorry but this keeps bringing back to the conclusion that this is a characteristic of the woofer.

Is that a 2235 in your Avatar? If so, how about providing us with a measurement of it in that cabinet?

Thanks for your input.

Where do you think those frequencies come from?

Hence my comments

[Mr. Widget]

The 2235's don't work the way they should looking at a 4430 frequency response plot.I am still confused... so Todd is annoyed by the fact that his measurements don't look the way he expects they should or he is hearing a problem and that is bugging him?


If it is the measurements that are the problem that is just silly... you can not make really meaningful measurements below 800Hz or so without an anechoic chamber... with great care and using special techniques you can get that figure a bit lower, but certainly not without CLIO, MLSSA or an equivalent.

If it is the sonics that are the problem, then what is he hearing that is bugging him?... and what does any of this have to do with the horn swap?


Widget

[toddalin]

I am still confused... so Todd is annoyed by the fact that his measurements don't look the way he expects they should or he is hearing a problem and that is bugging him?


If it is the measurements that are the problem that is just silly... you can not make really meaningful measurements below 800Hz or so without an anechoic chamber... with great care and using special techniques you can get that figure a bit lower, but certainly not without CLIO, MLSSA or an equivalent.

If it is the sonics that are the problem, then what is he hearing that is bugging him?... and what does any of this have to do with the horn swap?


Widget

Specifically, "It" is the dip in the 2235 equivelent frequency response centered below ~630. This plot taken at the woofer cone ~1/2" from near where the dust cap meets the cone. This shot is just the woofer without crossover.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/NF_No_xover.jpg

"It" offends my ear in that it results in a muting in that range that specifically manifests itself in the male voice. Regardless of how or where I test in the room in any position that any person would normally or unnormally (1/2" from the cone?) occupy, "It" manifests itself.

"It" was never there with the 130As that were changed to the 2235 equivelents at the general word of the Lansing Heritage Forum.

It has been chased for years by building new crossovers, remaging the woofers after already having them done, revising the crossovers, stuffing the cabinets, bracing, moving the cabinets, padding the area around the speakers, and on, and on, and on.

"It" has been the source of frustration time wasted. And according to the literature, "It" shouldn't be there.

The H92 was just another attempt to further minimize "It" by letting the horn play a little lower into the area inhabited by "It."

[4313B]

Like I said, you probably need to go audition a nice pair of loudspeakers on sale somewhere and leave all this DIY nonsense alone. It really isn't for everyone.

"It" was never there with the 130As that were changed to the 2235 equivelents at the general word of the Lansing Heritage Forum.Sell them as cores and cut your loses. Make them someone else's earache.

[Zilch]

Nearfield is a perfect setup for generating an interference cancellation midway between the side overhangs. It's certainly not eliminating that issue.

It is also not accurate above some low frequency at which reflections off the cone itself interfere. There's a formula for this, in D'Appolito, probably, but I wouldn't be trusting anything above ~200 Hz.

[pos]

toddalin, if the problem is in the driver itself then maybe use a sweep tone and listen to what happen around 600Hz. That may be a spider resonance or something?...
You can use WinISB beta for this, using the cursor to control the frequency.
If it is a panel resonance then you should also be able to hear or feel what happens.

[Robh3606]

It is also not accurate above some low frequency at which reflections off the cone itself interfere. There's a formula for this, in D'Appolito, probably, but I wouldn't be trusting anything above ~200 Hz.


Hello Zilch

Just for fun try doing some swept sine down there. I was getting -12db notches that would change frequency as I changed microphone distance close to the cone. At least the MLS made some sense and was repeatable with distance.

The whole things been whacky since day one. If the L200B worked fine so should this. Anyone have a pair of 200B's??

Rob:)

[subwoof]

The box, specifically the speaker / box combo is the problem. Period.

EVERY one of these threads / posts ( except ONE ) ignores the fact that the box is NOT designed for ruler flat ( 4430 ) response but to look cool in a living room back in the day when you played journey albums. With a sansuicide reciever.

if you want to correct the "problem" with the 630hz dip, use a different box. That's why the 4430 does not have this issue. You missed the point altogether when your measurements / comments said that the problem wasn't there when the 130A was installed. it's a DIFFERENT cone. So is the LE15B. JBL revised the crossover, LF cone and the porting but the box is the same size AND shape.

Having owned 4430's / L200's and refurbished a boatload of factory cabinets, I came to the conclusions here:

(1) JBL's cabinetry is really poor in the consumer dept and also in some of the pro lines. Their type of veneered particle board does NOT miter well, absorb glue evenly, tolerate mechanical fasteners, withstand shock or behave well with large pressures. Back when the L200's were designed, a 150 watt per channel amp in the house was RARE.

(2) I have removed bottom and back panels from these cabinets that actually RATTLE from disintegrated flakes. Even WITHOUT water damage. The wood just sucks.

(3) Misaligned assembly line nail gun adventures, some glue here, no glue there and "close enough" measuring meant that almost EVERY baffle rattles. And gee - if your cabinets were "closely matched" on the assembly line just maybe the same goof was done to both and that's why your "proof" ( they are the same response) is meaningless.

(4) No bracing to speak of and when it's put in, is so poorly aligned to make things worse. In short, make new cabinets that are the SAME SIZE as the 4430 and then the woofer / box response will behave.

(5) As was pointed out many times, and promptly dismissed by you, measuring below 800hz DOES require substantial equipment, a special room and the ability to gate the measurements. You have none of this so resistance is futile...:)

(6) I won't even go there on the crossover adventures or component selection. You have old, and will hear old. No value change, network Zobel or magic tweak will fix the box nodes.

Now I have a few hours of down time before I get inundated with grieving relatives and friends and I am writing this right after I gave a creditor a new orifice BUT arriving here monday is yet another pair of pristine, empty L200 cabinets.

THIS time I will make a new baffle that is almost flush with the front ( like dave's in a previous post ) that actually makes the internal volume larger to compensate for the bracing required to help break up the node and the new doghouse volume ( hint hint ).

I will be making a handful of the replacement baffles and pieces and might offer them as a "kit" for the DIY'ers that can walk and chew gum.

sub

[Beowulf57]

toddalin, if the problem is in the driver itself then maybe use a sweep tone and listen to what happen around 600Hz. That may be a spider resonance or something?...
You can use WinISB beta for this, using the cursor to control the frequency.
If it is a panel resonance then you should also be able to hear or feel what happens.

:thmbsup::applaud: Now this is a good idea! when I look at the woofer plot sans crossover, I am not only seeing dips at 630 and above, I am also seeing peaks which are unusual...no!? Why would a woofer show such a strange dip/peak rolloff characteristic? Destructive and constructive interference: cone breakup, resonances? Those peaks are really sharp. Did you try mass loading and externally damping the cabinet walls? I also assume that both channels show this identical anomaly? Go specifically for those problem frequencies as test tones using a signal generator and then listen to and touch the cabinets, woofer surround, etc. Track each one down if you can. I'd suspect crappy cabinet/baffle material...looks like particle board to me: is that what you have?

Years ago I had an extremely annoying resonance in my system, specifically from D131 when playing high brass instruments. I could not track it down until I pulled the driver and swept through the audio band: when the resonance appeared, I left it on that frequency and hunted around and found one of the input leads touching the speaker cone.

[Robh3606]

The box, specifically the speaker / box combo is the problem. Period.

Hello Sub

I wondered about that too but the L200B should have the same issues. May be they do?? Could be a very lively front panel. One thing I always remembered about my friends L200's was how lively the cabinet was.

Rob:)

[Mr. Widget]

Specifically, "It" is the dip in the 2235 equivelent frequency response centered below ~630. This plot taken at the woofer cone ~1/2" from near where the dust cap meets the cone. This shot is just the woofer without crossover.Thanks Todd for clarifying this for me... I think you have thrown good ideas after bad at this problem.

If it were my problem, I'd pull the offending woofers and measure them in test boxes. I would also use something with far more resolution than the Behringer you've got...

You are in the LA area, I would assume you could get the assistance of area Lansing heads... different 2235Hs, different cabs, better test equipment, more experience etc.

Good luck, I understand the frustration... in the past I've had a few of these disappointments too... two of them are posted deep in the threads here.


Widget

[grumpy]

Hi Todd,

If schedules can be coordinated, -and- I can borrow the wife's vehicle, -and- I take care
of the tree the fire dept. cut down :o:, I might be available Saturday w/ 4430's, test gear,
spare drivers, whatever you'd like to check/test. ...or some other time, whenever it might
work out.

[toddalin]

Hi Todd,

If schedules can be coordinated, -and- I can borrow the wife's vehicle, -and- I take care
of the tree the fire dept. cut down :o:, I might be available Saturday w/ 4430's, test gear,
spare drivers, whatever you'd like to check/test. ...or some other time, whenever it might
work out.

Thanks Grumpy. Someone is scheduled to come over this Satuday to put his Corvette on my lift. He has been chasing a fuel delivery problem. But we can make this happen. I'll get back to you.

[subwoof]

Well the LE15B / crossover was a problem with the L200

The L200B addressed / improved both. I assume that the same nodes are in play but I do not have a 200B to play with BUT the ones that are coming *might* be.

Myself, Heather, Zilch and others have plugged one port so the tuning should be not the problem.

The next generation L300 made the box bigger ( hint hint ) but KEPT the same woofer, added a tweeter and of course, new network. And added the wife-plant proof glass top.

So as time went on, and new materials and products evolve, it gets "better"

However, the old style is really nice to look at and with some work, the cabinet can be made usable so these efforts are not in vain.

sub

[toddalin]

How many times have we heard on this forum "There are a pair of L200 boxed on C/L, e-pay, etc. Go get them and throw in a couple 2235s."

Well, maybe that's not such good advise.

And as Rob has demonstrated, it is not just the L200 boxes, but many here won't read that (or just ignore it). If it wasn't a two person job, I would run these tests on my center channel that has a 2235 equivelent in ~6 cu ft with no edges sticking out.

If I find a way to measure that box and come up with the same results, can it then be assumed to be the woofers?

[4313B]

How many times have we heard on this forum "There are a pair of L200 boxed on C/L, e-pay, etc. Go get them and throw in a couple 2235s."

Well, maybe that's not such good advise.Maybe not. Hacking up ancient boxes of marginalized performance and built of substandard materials is half-assed DIY as far as I'm concerned. It was half-assed 30 years ago and the stuff doesn't age well. Build or commission to have built what you need and do it right. One of the highlights of DIY is not being locked into the whole engineering/designing/manufacturing/sales/marketing round and round. You only have to satisfy yourself. You can build or have built anything you want and you don't have the same rigid constraints and plethora of opinions a corporation usually has.

[subwoof]

Well getting a 1967 camaro with a 250 6cyl and just drop a 396V8 and be done with it doesn't make sense either. and it will STILL drive like crap with that front end. :)

Wrong suspension, fuel system, driveshaft, tires, brakes,etc means to do it right it's a complete do-over.

With these old speaker systems it's the same except you have to add the box ( chassis ) into the equation.

We do it, and enjoy doing it, and usually enjoy the results.

Like restoring an old car frame-up, you can never justify the time and money but you do get to show it off. And that's the whole point.

The reason so many comments are "stick a 2235 init " is that it's the most cost-effective replacement that can give good results.

The average DIY person does not have a cabinet shop - and conveying desires to one that is NOT specifically know how to do it is near impossible if you want them built right.

Therefore the "redo" is the only option.

Notice that we didn't say "move the woofer hole over 2 inches " to see if that would help? And change the slope of the baffle 5 degrees?

As said one hundred times before, and often quoted, is that this is a series of compromises and that's that.

Besides after 2 beers who's gonna notice. If you miss greg lake's deep vocal so much, get a pair of 4343's.

sub

[4313B]

Therefore the "redo" is the only option.That's a total bummer. :(
I'd find something else to do if that were my lot in life.

Besides after 2 beers who's gonna notice.Very good point! Even L100's at frat parties were known to sound really, really good! :rotfl:I know I sure enjoyed having them around at the time.

[hjames]

Thank you sir!
I may be ambitious, and love to tinker about with the JBLs, but I'm certainly no cabinet maker! I can swap speakers and even wire up a crossover from a schematic, but wood work - pah!! (wish I could)


... The average DIY person does not have a cabinet shop - and conveying desires to one that is NOT specifically know how to do it is near impossible if you want them built right.

Therefore the "redo" is the only option.

Notice that we didn't say "move the woofer hole over 2 inches " to see if that would help? And change the slope of the baffle 5 degrees?

As said one hundred times before, and often quoted, is that this is a series of compromises and that's that.

Besides after 2 beers who's gonna notice.

sub

[toddalin]

However, the old style is really nice to look at and with some work, the cabinet can be made usable so these efforts are not in vain.

sub

I was able to redirect the Behringer to the 6 cu ft center channel with two 11" x 4" ports and "it" does not manifest itself in the nearfield to the extent it does with the L200 cabinets. This then leads again to either a box/woofer relationship or a problem in the woofer.

Assuming its the box/woofer relation, OK, what work? I've stuffed it, braced it, re-glued it, tilted it, moved it. What am I missing to make it "usable" with these drivers?

[Beowulf57]

That's a total bummer. :(
I'd find something else to do if that were my lot in life.
Very good point! Even L100's at frat parties were known to sound really, really good! :rotfl:I know I sure enjoyed having them around at the time.

Now, there's the real point: forget the measurements...do you like the sound enough to kick back and just enjoy? If not, knuckle down and find that problem! :banghead: Keep on banging until you get the insight you want...it's all just :blah: until you find out for yourself! :D

[toddalin]

do you like the sound enough to kick back and just enjoy? If not, knuckle down and find that problem! :banghead: Keep on banging until you get the insight you want...it's all just :blah: until you find out for yourself! :D

No, and that is the problem. But I keep getting just a little closer, and I don't really want to just throw eq at it.

Sure I could get something else. But there is so much that these things do right that I do enjoy. If I could just get this one niggling problem solved, I would be a very happy camper.

When Grumpy came by last time he brought over a 500 Hz crossover. This actually provided about the smoothest response as it cut the woofer at the anomoly and let the horn go lower to help fill the void. As I said before, if I can't raise the bridge, maybe I can lower the river a little more.

[1audiohack]

Its hard to follow this through all the threads its scattered in, so this may have been done and I missed it.

Are you still running with one open port and the bullit in the other?

Have you measured with both ports stuffed shut?

You may want to read the "Port Resonance" post dated 3-5-08.
There are even a couple of measurements there for food for thought.

[grumpy]

IIRC, the port resonance would be in the 1600-1700 Hz range... (2nd port plugged)
but Todd has physical access (much better than depending on my recollection
of port size/depth) :) If that's the problem, it should be very simple to test.

[toddalin]

Its hard to follow this through all the threads its scattered in, so this may have been done and I missed it.

Are you still running with one open port and the bullit in the other?

Have you measured with both ports stuffed shut?

You may want to read the "Port Resonance" post dated 3-5-08.
There are even a couple of measurements there for food for thought.

Yes, I've done it with no ports open, one port open, or both ports open. (Tweeter sits above horn.) No observable difference regardless. If I recall correctly, ports are 7" long 4" diameter.

[4313B]

This then leads again to either a box/woofer relationship or a problem in the woofer.Testing for the sake of testing (such as putting the woofer on a 4x4 sheet of wood) may prove interesting and may even show the woofer to be linear, it doesn't solve the problem.
Assuming its the box/woofer relation, OK, what work? I've stuffed it, braced it, re-glued it, tilted it, moved it. What am I missing to make it "usable" with these drivers?I don't think we ever put the real 2235 in the cabinet. (No sense in putting a screwdriver through the cone which is always my fear with mounting/dismounting.) I think we used it for reference in the WT-2 tests.
When Grumpy came by last time he brought over a 500 Hz crossover. This actually provided about the smoothest response as it cut the woofer at the anomoly and let the horn go lower to help fill the void. As I said before, if I can't raise the bridge, maybe I can lower the river a little more.Sounds like you have it licked then! No sense in forcing those 2235A's to do something they can't do.
Drop the crossover frequency down to 500 Hz and call it done. That's why JBL made LX5's.

Glad we all could help. :applaud::yes: :cheers:

[toddalin]

Drop the crossover frequency down to 500 Hz and call it done.

Glad we all could help. :applaud::yes: :cheers:

Well that's exactly what I have been trying to do with these crossovers/horns.

Using the previously provided schematic, what capacitor values get me closest for the high pass on the mids?

Thanks.

[4313B]

Using the previously provided schematic, what capacitor values get me closest for the high pass on the mids? Ian has it modeled for you but he says it's jacked.

I don't have an LE175/HL92 on hand to measure the impedance and frequency response to plug into LEAP. Nor do I have the impedance and frequency response of your 2235A in your L200 box. Sorry. :dont-know

You should be able to find LX5's (3115) and N8000's (3106) to use.

[grumpy]

Certainly welcome to borrow a pair of 3115A's... no N7000/8000's though.

I'm curious about the dip, but whatever punts this through the field goal works for me :)

Appears 4" vent would need to be more like 10" long (if fairly clear at the rear) to get
down to the 600Hz range, resonance-wise.

[Beowulf57]

Well that's exactly what I have been trying to do with these crossovers/horns.

Using the previously provided schematic, what capacitor values get me closest for the high pass on the mids?

Thanks.

Hmm...if that's route you decide to go, I'd try the 3115A's that grumpy offered feeding directly to your LF drivers and then into the appropriate points in your existing MF and HF sections (to allow the low pass and L-pad elements to remain in circuit to the MF and the high pass and L-pad elements to the HF). Just changing the capacitor and not the inductor in your existing design will muck up the impedance matching and introduce other anomalies...I think?:blink: Someone with more knowledge, please correct me if I am speaking :bs:.

[Ian Mackenzie]

I dont think its been documented but the L200 box has almost identical depth and wide and dimfor wavelength when cancelled of a said notch. Compare to the 4430 dimensions and the L200 is a problem box from the point of golden ratios.

As has been stated earlier under certain conditions a box can be a problem. Usually one dimension is not too bad , but add a second node in the same region and the problem gets worse.

I doubt Toddlin will bother but it may be worth looking at internal shelf bracing or specialised non invasive damping materials to break up modes of potentially poor dimentional ratios.

Over on eastcoast audio there is an interesting discussion on the effectivements of damping panels and boundary layer damping

http://sound.westhost.com/articles/boxstuff.htm

[subwoof]

The only variable not suggested here is the one that should work. Make the box bigger.
I would suggest taking a 5/4 pine frame that's about 22 X 28 and cover it with 3/4 MDF

Depth will be the variable here - it needs to compensate for the additional bracing and box retuning. On the JBL old graphs 5.5ft3 was the target for the DIY boxes and the 4430. Go bigger and tweak your way back down. This DOES matter.

As Ian said, and another post before, dimensions that match are bad. If width AND depth match, REAL bad. This is specifically mentioned in JBL's enclosure building manual ( in the tech section ).

This would be a huge version of the cover you made for the driver and would increase the box volume and CHANGE the depth.

You can then add bracing, fill, solid wood ( to tweak the volume ) and such until you get this node either moved up to the Xover Freq, removed or marginalized.

Get a tube of mean mean construction adhesive and add some 2X4's to the sidewalls but NOT with the exact same distances from the front. This will both strengthen (as best that it can ) the sides AND somewhat breakup the nodes.

Time to do some math..:o)

sub

[Beowulf57]

Excellent points Ian & subwoof :applaud:. So...most likely the problem is destructive interference due to internal standing waves, with a possible contribution of panel resonances. Solution:

1. Breakup the internal modes and use panel damping.

2. Drop the crossover point (e.g., LX5/3115/3115A) and attenuate those problem frequencies in the box.

[subwoof]

Well there is the mother of all marshmallow toasts we did each summer to "retire" some old PA and misc boxes. That worked. Once that particleboard goes, it's over.

Who knows what toxin's were added to our S'mores then.

And to assuage the cons-pro debate, I have a pair of rebuilt 4315B and 4331 where the baffles, joints and backs just plain rattled and they looked like they were assembled on a union friday afternoon...horrible workmanship.

The first gen cabarets were from an outside vendor that apparently didn't understand how to measure. Drop one and it's time to reglue all the seams.

1/4 inch GAPS in the bracing, even when the cheap hot glue is added, did NOT brace them...!

gotta go. see you guys monday

[1audiohack]

Posts of real substance seem to be getting slim around here.

I remember someone saying in a Zilch post that he was "exploring for the sake of exploring." I can't think of a better reason! Taking the time to share it with the rest of us is very cool.

I am glad there are knowlegable folks here that are willing to jump in and try to help when someone has a problem.

It is of great bennefit to those of us really trying to learn AND understand. Even if from the sidelines. Were hungry for knowlege

If it was easy, everyone would be doing it, with good results.

Thanks.

[Beowulf57]

:rotfl: Yeah...

Does anyone even read this stuff we post? :rotfl:Well, maybe that's the wrong question. Does anyone even understand the stuff we post? :blink:

Well, I do...though I'm not sure how many understand what I post...myself included ;):D.

[Beowulf57]

I can fully comprehend what I post up to ten minutes after the posting...

I'm good for 15 minutes due to eating my

[toddalin]

I doubt Toddlin will bother but it may be worth looking at internal shelf bracing or specialised non invasive damping materials to break up modes of potentially poor dimentional ratios.



Whos' not reading? I've done some extra bracing and fiberglass both to little avail. I put 2"x2" in to brace the front to the back and they are also tensioned through the horn. The 2"x2" didn't seem to do anything except get in the way, so it was removed. :(

I have devised another idea to break up internal waves without cabinet modifications. I've made the prototype and will try it out when I next open the cabinet. :hmm:

[BMWCCA]

If it was easy, everyone would be doing it, with good results.

Maybe you should change the forum name to "Do It To Yourself" forum: DITY Forum

or

"I Did It — Or Tried" : IDIOT Forum ;)

[pos]

Here are the internal measurements of my L200 (not B) :
H 73cm
L 57cm
D top 29cm
D bottom 39cm

[toddalin]

Pulled the woofer out again today to try a different approach. First off, this is the picture Ian asked for of just the woofer out of the cabinet tilted up at an angle so as not to block the vent. The mic was about 6" above:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Out_of_Box.jpg

Sorry Ian, I did not have Home Depot deliver a 4'x8' sheet of wood nor will it fit in my car.

Note that the woofer out of the cabinet almost "mirrors" what the in cabinet plot of the woofer is doing almost as if they are out of phase:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/NF_No_xover.jpg

I've also noticed that when I rap on the cabinet sides, it spikes in those frequencies.

It was postulated that if this was a cancellation at the cone from the rear wave, simply breaking up the rear wave reflection should show some differences.

I fabricated a donut out of 2" thick styrofoam that would snug-up on the woofer magnet and block the rear wave.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Donut.jpg

And put is all back together for testing. This is the result again with the mic at the reference point (i.e., 78" away and 32" above the floor). The results were less than sucessful. Conclusion, the cabinet or cabinet/woofer combination is for sh-t. :blink:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/With_Donut.jpg

[Zilch]

How many times have we heard on this forum "There are a pair of L200 boxed on C/L, e-pay, etc. Go get them and throw in a couple 2235s."WHO? :duck:

The vents in the overhang would not prevent the LF from reflecting back and forth in the woofer area. What material has good attenuaton in the region of 500 Hz?

http://www.bobgolds.com/AbsorptionCoefficients.htm

I do not consider dropping the XO frequency to 500 Hz a rational solution. LE175 on HL92?

Find the problem, if there is one, and fix it.

Widget heard my L200s here several times. Once, he said he heard a resonance. Next time, he didn't. He certainly never suggested there was a hole in the midrange response @ 600 Hz.... :dont-know


I fabricated a donut out of 2" thick styrofoam that would snug-up on the woofer magnet and block the rear wave.Front and rear are not parallel surfaces. It's side to side that calcs to the problem frequency, and the styrofoam donut not going to stop it, if that's the source.

[Zilch]

Neither is sticking in series resistors dude!I've argued vehemently against that one from the beginning.

Trying to think of what more I might do here. I like your groundplane suggestion. Todd's got the room to try that.

Footnote: There's irony here. I get summarily dissed for cutting PT waveguides into my L200s, but now we're gonna hack the overhang off? :p

I'm certainly glad you and Greg established that not likely to be the source of the problem.... :yes:

[subwoof]

In the mothball section of the shop is an old HP 5200 series synth oscillator I snagged from a GE sonar lab many years ago. This was built to withstand a nearby detonation and is a monster of over design.

It will go from .01hz to 100khz in .01hz steps just by pushing buttons. And it has a sweep inside of a range control which makes looking for trouble a snap.

Maybe using this on one of the boxes that are coming will see if a nasty node is lurking. With GT's comment about the lack of a JBL measured anomaly, I stick with my earlier surmise that the same assembly line construction defect is to blame.

Ever run over interstate downhill off-ramp ripples with a single bad front end shock? Dance on a volcano time.

Shaking the crap out of mine will not test todds but it will point out the same node IF the dimensions are the culprit.

sub

[grumpy]

Hi Sub... looking forward to your cabinet shake-down.


I also asked Grumpy via PM if he ran the TS parameters through BB6 to check for errors, mechanical or electrical.Plugged a minimum set of parameters from the WT2 output into the WinISDpro
editor and let the remainder be calculated... as expected WT2 produces
self-consistent results... albeit, based on the measurements and therefore
the operator skill/experience. This is not trivial if accuracy is desired.

Two things looked off, but not crazy off:

1) Mms measured as 195g vs spec of 155. This threw off BL and Vas
a bit but not hugely so. Vas goes from ~12ft3 (measured) to ~15ft3,
BL goes from ~23 (measured) to ~21. I.e., using 155g for Mms produced
more normal results for other, calculated, parameters. I'll assume, for now,
that 155 is the correct Mms value.

2) Qms seems high as measured vs spec (8.7 vs 2.5) affecting Rms
(inversely) and Cms somewhat less.

I'm certainly willing to accept that the Mms measurement might be off
(more due to "technique", than any shortcoming of WT2).

Fairly large variations in Qms do not -appear- to be a dominating factor in response
(in reviewing WinISD's 2235H model vs. "2235A" in an L200-sized box
with a single 4" dia, 7" long port)
but an expert will have to chime in if a 3x diff in Qms is a big deal in
production... or not.

[Beowulf57]

Pulled the woofer out again today to try a different approach. First off, this is the picture Ian asked for of just the woofer out of the cabinet tilted up at an angle so as not to block the vent. The mic was about 6" above:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Out_of_Box.jpg

Sorry Ian, I did not have Home Depot deliver a 4'x8' sheet of wood nor will it fit in my car.

Note that the woofer out of the cabinet almost "mirrors" what the in cabinet plot of the woofer is doing almost as if they are out of phase:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/NF_No_xover.jpg

I've also noticed that when I rap on the cabinet sides, it spikes in those frequencies.

It was postulated that if this was a cancellation at the cone from the rear wave, simply breaking up the rear wave reflection should show some differences.

I fabricated a donut out of 2" thick styrofoam that would snug-up on the woofer magnet and block the rear wave.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Donut.jpg

And put is all back together for testing. This is the result again with the mic at the reference point (i.e., 78" away and 32" above the floor). The results were less than sucessful. Conclusion, the cabinet or cabinet/woofer combination is for sh-t. :blink:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/With_Donut.jpg

Toddalin,

These plots are the first I've seen which show a change that is revealing. First, the dip disappears when the woofer is out of the cabinet, and second you observed spikes at the frequency problem areas when you rapped the cabinet walls.

So, I have a question: do both woofers & cabinets give identical results?

[toddalin]

Toddalin,

These plots are the first I've seen which show a change that is revealing. First, the dip disappears when the woofer is out of the cabinet, and second you observed spikes at the frequency problem areas when you rapped the cabinet walls.

So, I have a question: do both woofers & cabinets give identical results?

:dont-know The assumption all along has been that both woofers in both cabinets are doing essentially the same thing. When the Yamaha goes though its auto eq mode, it applies about the same eq (in that area) to both speakers. The far cabinet is less ameaniable to testing.

However, I did find a way to test the center cabinet (6 cu feet with two 11"x4" ports), and it shows a fairly characteristic 2235 curve, not unlike the woofer out of the cabinet, but without most of the rise with frequency.

BTW, I attribute much of that rise to the Zobal network (even though the woofer is out of the box, it is connected to the crossover in the picture).

Again, the rise was intentional to compensate for the dip, just as I was trying to do with the low end of the horn. Essentually, I was constructing crossover/bump filters.

In testing the center channel, for that particular speaker the rise is a bit much, and that Zobal network will probably have its capacitance increased when the cabinet is reopened.

[Ian Mackenzie]

http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html


If you plug in the box dimension it will give an indication of what is happening.

This is distinct from the panel resonances

[Beowulf57]

:dont-know The assumption all along has been that both woofers in both cabinets are doing essentially the same thing. When the Yamaha goes though its auto eq mode, it applies about the same eq (in that area) to both speakers. The far cabinet is less ameaniable to testing.

However, I did find a way to test the center cabinet (6 cu feet with two 11"x4" ports), and it shows a fairly characteristic 2235 curve, not unlike the woofer out of the cabinet, but without most of the rise with frequency.

BTW, I attribute much of that rise to the Zobal network (even though the woofer is out of the box, it is connected to the crossover in the picture).

Again, the rise was intentional to compensate for the dip, just as I was trying to do with the low end of the horn. Essentually, I was constructing crossover/bump filters.

In testing the center channel, for that particular speaker the rise is a bit much, and that Zobal network will probably have its capacitance increased when the cabinet is reopened.

Right:blink:...so, you've discovered that it isn't likely to be the woofer, or room nodes but from what I can tell the cabinet dimensions might be an issue :( (closest problem appears to be the width at 57 cm which gives destructive interference at 616 Hz and the depth at 29 cm also gives 616Hz). Also did you check the walls resonating from the outside? ...clamping of 2x4's to the sides with large box clamps, or two big guys pushing hard with their hands on opposites sides of the cabinet :D, and see if that dip lessens.:banghead:

[toddalin]

Also did you check the walls resonating from the outside? ...clamping of 2x4's to the sides with large box clamps, or two big guys pushing hard with their hands on opposites sides of the cabinet :D, and see if that dip lessens.:banghead:

I don't have clamps anywhere near that size nor are there any football players in the area. As much as I try, I am not able to manifest a difference by pushing on the cabinet by myself.

[Beowulf57]

I don't have clamps anywhere near that size nor are there any football players in the area. As much as I try, I am not able to manifest a difference by pushing on the cabinet by myself.

Did you hear the story about three holes in the ground? Well, well, well! :hmm:How about trying the 3115A crossovers that grumpy has? Check the maximum drive into the LE175's with a digital Multimeter and if you can confirm that you'll never overdrive them at any reasonable listening level...forget the measurements and see if you like the resulting sound with the crossover lowered to 500Hz on the LE175/HL92? Cheaper and easier than replacing cabinets. That's the best I can come up with at the moment, except to say I'm very happy with that crossover point in my system. :thmbsup:

[Ian Mackenzie]

Muhahahah.

It would be quite amusing if we got some crossovers based on the Component Series Guide and put them in there and the Freakin "problem" went away. I've seen dumber things with diy.;)

I mean I recall earlier seeing a Series Crossover Schematic.:blink:

(nothing in this post should be taken particularly seriously:barf:)

[johnaec]

Of course, you could always pick up this pair, (he has 2 auctions), of NIB 2235H speakers: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=330288784756&ssPageName=STRK:MEWA:IT&ih=014

That way, you'd *know* the speakers aren't the problem...

John

[toddalin]

I hauled one of the 43** clones in and sat it next to the L200 cabinet. The 43** has a real 2235H, 2420/2307, and 3110. The existing L200s have a 2205 reconed as a 2235 (a legit make-over), LE175/2312, and 075s.

To me the difference was like night and day. The voices instantly popped out with full authority! :applaud:

I called Linda in the room and her first comment was that she didn't like the cabinets and much preferred the slanted L200 cabinets.

Then I sat her down to listen and the difference was instantly apparent to her. Vocals took on a much greater clarity and intelligibility.

I've not yet tried changing the actual woofers out nor looked at the spectrum with the Behringer, but expect the suspect the dip is greatly diminished with these cabinets and would be so with the 2235 equivelents.

Now I have the delimma of sound vs. decor. :banghead:

[Zilch]

Now I have the delimma of sound vs. decor. :banghead:No, you have is an incomplete answer, is what.... :blink:

[toddalin]

Thanks Heather, I've seen Giskard's crossover and it is actually very similar to what I've been using, at least for the woofer where the problem seems to lie.

I don't think this is a crossover problem and the original design I was using, (before tweaking to fill the dips) should serve just fine in a different box. Zilch even tested it in various other speaker box configurations and liked it. The tweeter circuit is somewhat different becaue I use the 075s instead of the 077s.

Use of the 3115 (500 Hz) crossover may be better for the L200 cabinets if it crosses over to the woofer before the anomoly. (Still have to try that one now that I have them.)

[Beowulf57]

Glad to hear that at least you can get it to sound good in your room! That should take the room out of the equation...at least as far as it isn't a major contributor.

Now, wow! :bouncy: What possibilities for experimentation:

1. Slap the 3115's into the L200's: in one fell swoop that takes the woofer, cabinet construction resonances and internal destructive modes out of the picture to a large degree as the problem frequency area is no longer rattling around inside the box. If that sounds good, you can keep your prettier L200 cabinets in action.

2. Swap the 2420's with the LE175's just for fun to see if that sounds any different.

3. Swap woofers and see if the dog's bark improves.

4...

Are you having fun yet? :rockon2:

[toddalin]

No, you have is an incomplete answer, is what.... :blink:

OK, did some comparison tests.

This is the real 2235H in the 43** equivelent cabinet at the reference distances (i.e., 78" away 32" high). Even though the cabinets are side-by-side, it is not exactly the same position as with the L200 because of the physical dimensions of the cabinets, furniture in the room, and the inability of my back to keep moving cabinets around on the carpet. Like the L200, the 43** has two 4" diameter ports that are 7" long. As with the L200 cabinet, one was plugged for testing. The cabinet does appear to have a little more interior volume than the L200.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/4420_Ref.jpg


Contrast this with the 2235 equivelent in the L200 cabinet at the reference position.
http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Woofer_Without_Crossover.jpg

This is the nearfield on the 43**/2235 (~1/2" from where the dustcap meets the cone).

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/4320_NF.jpg


And again this same position on the 2235 equivelent in the L200 cabinet.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/NF_No_xover.jpg

Who wouldn't hear a difference? If I could just get rid of the midrange dip, the L200 cabinet/2235 equivelent would have the nice curve. ;)

[Zilch]

Swap the woofs and retest.

Leave the cursor in the same position, please.... :banghead:


did that last post of Todd's lose some pictures? :blink:Must be, 'cause I'm seein' the same hole in both from the listening position.... :dont-know

[subwoof]

Did you notice that the 43XX horn is not the 2307 but the longer 2312?

And the midrange driver has the higher flux magnet?

And the 43xx cabinet's panels and baffle are thicker too..:o)

3 more variables that would also affect the "dip".

Apples and oranges.:)

btw the 200B cabs arrived today - they need some work. The PARTICLE board 3/4 front panel has numerous chips from woofer mis-adventures of old.

sub

[toddalin]

Did you notice that the 43XX horn is not the 2307 but the longer 2312?

And the midrange driver has the higher flux magnet?

And the 43xx cabinet's panels and baffle are thicker too..:o)

3 more variables that would also affect the "dip".

Apples and oranges.:)

btw the 200B cabs arrived today - they need some work. The PARTICLE board 3/4 front panel has numerous chips from woofer mis-adventures of old.

sub

No, the 43** has the 2307 horns. The L200 has the 2312.

cabinet panels are 3/4" particle board. These are copies.

Midrange has no bearing on this.

Ultimally I did lots of listening this evening to the 43** and the L200 A/Bing them (just one). The 43** have a slightly more pronounced vocal range, but the L200s seem to do about everything else as well and usually better with a more natural, open sound, possibly due to that nice crossover I built. Maybe vocals suffer but guitar is no contest and sounds much better on the L200s. Even comparing just the two woofers in the two cabinets without crossovers/horns reveals these traits.

Both together seems to be the best of both worlds.

[toddalin]

Now, wow! :bouncy: What possibilities for experimentation:

2. Swap the 2420's with the LE175's just for fun to see if that sounds any different.

Are you having fun yet? :rockon2:

I've set it up so that I can instantaneously A/B any two speakers or components within those speakers. I have a 43** and an L200 sitting side by side and connected the LE175/HL91 as "A" and the 2420/HL91 as "B". I can toggle between the two and they are both wired to the same crossover network using the 2235 equivelent and 2402 in the L200 cabinet. So other than the horn jumping to the side by 2', everything is the same. While I've compared LE85 drivers in the past, it was always on their respective speakers or having to take the time to swap out cables.

Due to small differences in the frequency responses, the 2420 is brighter and more articulate with better clarity of vocals (much appreciated). But the music sounds more "aniseptic" and disjointed from the woofer.

The LE175 on the other hand has a warmer, darker sound, but it is more natural. The sound meets and reinforces the woofer better, almost to the point of making things sound a little "tubby" sounding. Vocals aren't as clear, but some/most other instrumentation sounds better. Over time, it could be less fatigueing.

Much of what sounds better/worse is based on the range of that instrument and how it falls within the frequency response of the different drivers. This is going to be a hard choice, and I guess I really need to make it based on the HL-92 horns that would ultimately be employed. So, I guess I'll have to slap a 2420 on an H92 and mount that for listening to compare it to the other L200 that has alrady been converted to an H92.

[Beowulf57]

I've set it up so that I can instantaneously A/B any two speakers or components within those speakers. I have a 43** and an L200 sitting side by side and connected the LE175/HL91 as "A" and the 2420/HL91 as "B". I can toggle between the two and they are both wired to the same crossover network using the 2235 equivelent and 2402 in the L200 cabinet. So other than the horn jumping to the side by 2', everything is the same. While I've compared LE85 drivers in the past, it was always on their respective speakers or having to take the time to swap out cables.

Due to small differences in the frequency responses, the 2420 is brighter and more articulate with better clarity of vocals (much appreciated). But the music sounds more "aniseptic" and disjointed from the woofer.

The LE175 on the other hand has a warmer, darker sound, but it is more natural. The sound meets and reinforces the woofer better, almost to the point of making things sound a little "tubby" sounding. Vocals aren't as clear, but some/most other instrumentation sounds better. Over time, it could be less fatigueing.

Much of what sounds better/worse is based on the range of that instrument and how it falls within the frequency response of the different drivers. This is going to be a hard choice, and I guess I really need to make it based on the HL-92 horns that would ultimately be employed. So, I guess I'll have to slap a 2420 on an H92 and mount that for listening to compare it to the other L200 that has alrady been converted to an H92.

Hi Toddalin,

I assume you mean the LE175/HL92 as "A" rather than HL91? I would agree that comparing using the same horn is desirable.

The 2420 has a more extended top end than the LE175, though if the crossover rolls off the upper end of the MF, that shouldn't make a large difference. Perhaps the 2420 has a different response in the vocal range, compared to the LE175...but I've never listened to the LE175, so can't comment on this point.

However, melding with the LF is another issue related not only the the horn, but also phase and level. My LE85's sounded best in phase on the HL91 and out of phase on the HL92...mind you, with a 500Hz crossover. May be different in your system. Also, I ended up using an L-pad to knock the MF level down to around -11dB and the HF (2405H) is around -7dB. This is based upon the LX5 crossover attenuation settings of -5 -7 -10...I set it at the mid (-7) and use the L-pad to knock the MF down roughly another 4 dB. Setting the LX5 to -10 was almost right for the LE85's but didn't allow enough level for the 2405H's...hence my use of the MF L-pad. The L-pad for the 2405H's (3106 crossover) is set full up. This gives nice non-fatiguing and rich balance with the LF, good articulation in the midrange and enough level to give the trebles a nice crisp, yet delicate presence.

P.S. Given that your warts are large enough to handle the 2420's, you might be able to swap them in for the LE175's and then use your L-pads to adjust the frequency balance and get the woofer/midrange integration, midrange articulation and upper registers you are looking for...?

[toddalin]

Hi Toddalin,

I assume you mean the LE175/HL92 as "A" rather than HL91? I would agree that comparing using the same horn is desirable.

The 2420 has a more extended top end than the LE175, though if the crossover rolls off the upper end of the MF, that shouldn't make a large difference. Perhaps the 2420 has a different response in the vocal range, compared to the LE175...but I've never listened to the LE175, so can't comment on this point.

However, melding with the LF is another issue related not only the the horn, but also phase and level. My LE85's sounded best in phase on the HL91 and out of phase on the HL92...mind you, with a 500Hz crossover. May be different in your system. Also, I ended up using an L-pad to knock the MF level down to around -11dB and the HF (2405H) is around -7dB. This is based upon the LX5 crossover attenuation settings of -5 -7 -10...I set it at the mid (-7) and use the L-pad to knock the MF down roughly another 4 dB. Setting the LX5 to -10 was almost right for the LE85's but didn't allow enough level for the 2405H's...hence my use of the MF L-pad. The L-pad for the 2405H's (3106 crossover) is set full up. This gives nice non-fatiguing and rich balance with the LF, good articulation in the midrange and enough level to give the trebles a nice crisp, yet delicate presence.

P.S. Given that your warts are large enough to handle the 2420's, you might be able to swap them in for the LE175's and then use your L-pads to adjust the frequency balance and get the woofer/midrange integration, midrange articulation and upper registers you are looking for...?

I think you missed the jist here. I was comparing the LE175 on the HL91 in the L200 cabinet that has yet to be converted to the 2420 also on the HL91 in the 43** cabinet. This way I am only comparing one variable at a time; the driver. Placed next to the wart cabinet with the HL92, the HL92/LE175 proved the clear winner, but I was comparing several variables simultaneously (e.g., cabinet, woofer, driver, horn, crossover).

In this case I found the LE175 to have a warmer sound with better ambienance, but the 2420 to articulate better. In the past, I had alway preferred the warmth of the LE175s to the LE85s I had tried when used in a 3-way set-up.

But I set up a more meaningful way to compare them keeping all other variables the same as much as reasonably possible. For instance, in this way even though the sound of the horn shifted 2' over, it still used the same lens on a similar arrangement baffle. Not exactly the same, but similar. Although the horns could have been closer together, I feel that it would be less meaningful comparing the horns out of the cabinets sitting on top with no baffles behind the lenses (or no lenses) just to get them closer. (One of those dual driver adapters..., yeah, that's the ticket.)

I will slap a 2420 in my wart cabinet on the H92 (I did make this provision in the design) and I'll put an HL92 on the other 2420 in the 43** and compare them that way before making a final decision. In that case, those drivers will also be phased the same; whichever way provides the best integration with the L200 cabinet. Maybe the extended horn can provide some of the warmth to the 2420 that I'm missing from the LE175 while retaining the articulation.

I'll have to invite the locals over to help document the findings. ;)

[Beowulf57]

Right Toddalin...I didn't grasp that only one L200 had been converted to the longer horn. You've got the experiment well in hand...only to be expected after so much work and preparation on your part :applaud:.

Though I can't comment on the LE175 vs LE85/2420 sound, I do know that changing MF phase produces changes in "perceived" warmth/richness as does changing the level of the MF. Nevertheless, my ears have never heard what you hear and prefer and vice versa...your "warm & ambient" sound may well be different from mine.

I'll keep my fingers crossed that you are getting close :bouncy:.

[Chas]

[quote=toddalin;229634]I've
The LE175 on the other hand has a warmer, darker sound, but it is more natural. The sound meets and reinforces the woofer better, almost to the point of making things sound a little "tubby" sounding. Vocals aren't as clear, but some/most other instrumentation sounds better. Over time, it could be less fatigueing.
quote]

Reading this reminds me of the time I mounted my LE175's to my Altec 511B's. The result was a nice big, warm sound, that was really fun to listen to. Accurate? I don't think so, but it was musically seductive.....:)

[Beowulf57]

[quote=toddalin;229634]I've
The LE175 on the other hand has a warmer, darker sound, but it is more natural. The sound meets and reinforces the woofer better, almost to the point of making things sound a little "tubby" sounding. Vocals aren't as clear, but some/most other instrumentation sounds better. Over time, it could be less fatigueing.
quote]

Reading this reminds me of the time I mounted my LE175's to my Altec 511B's. The result was a nice big, warm sound, that was really fun to listen to. Accurate? I don't think so, but it was musically seductive.....:)

Which reminds me: we're also talking about optimizing for a particular set of components on both sides of the speakers. I use a Linn LP12 and Unidisk SC and my amps are P-P DHT's...so I get lots of warmth and ambience to begin and end with...probably don't need so much in the speakers.