Sub Question....

[lpd]

Ok I have a couple questions for the pro's here. I have a three way horn system, half JBL half other's. I have a mid-bass (100hz-500hz), cd horn 500hz-rolled off), tweeter (6000K + ). For subs I have 2 2235's. I put them into a pair of L45 flair cabs and blocked the holes just to test them, but am unsure how to wire them into the system. My preamp only has one output and I tried the tape out into a cheapo electronic car crossover at 100hz. Problem is they sound mushy and I can't blend them at all with my other drivers. I want to blend both subs into the stereo . I have a 200 watt Acoustat TNT amp for output. I also tried an integrated amp and plugged into an aux input from the crossover and used the volume knob for gain but things got mushy.



Any ideas here...is the crossover the problem, the cabs or using the tape out, or all three?

I really new to this so please bare with me.

[scott fitlin]

You have two problems, the first and foremost is you arent getting a proper signal to the xover from the tape out, you need a master out to supply the requisite preamplified signal and drive level. Second is the crossover, car crossovers are generally inexpensive and not so great. The proper xover will have better drive, cleaner signal, and better, make that far better accuracy.

For a crossover I can recommend several models, depending on your budget.

If you really want to do this economically, and get really nice sound, you can get a Crown VFX-2A off Ebay. Then you can cross your subs over at 100hz, and overlap your full range wherever you wish. You can let the full range cabs run all the way down, or to 40hz or 30hz, or whatever you choose. The VFX also has balanced ins with user definable gain, that comes in handy, too. You will have to use your amplifier input level controls, as the VFX has no output level attenuators, but this will work.

And yes, I agree with Zilch, you do want to run your subs in stereo!

[Zilch]

From L45 Flair dimensions, BB6P calculates a box just over 5 cuft.

If you've closed off all openings, inculding the ports, you're running closed box, the black curve below.

BB6P suggests tuning that box to 24.6 Hz (red). A single 4" ducted port 7.25" long will do that.

If you have the ports closed off, open them. I don't know what size or length port is in L45, but if you'd measure it, I can determine the present tuning, which may be just fine.

Tape outs should run them through your additional amp, but you'll have to control the volume separately with that. You also need a crossover, as you already know.

Ideally, your single preamp out should go to an active crossover like M552 or 5235 running your two amps.

Also, everything has to be phased correctly for them to blend worth a whit....

[Zilch]

I have a 200 watt Acoustat TNT amp for output. I also tried an integrated amp and plugged into an aux input from the crossover and used the volume knob for gain but things got mushy.You plugged into the aux input from what crossover? The cheapo car audio one? I don't get that. Is it an active crossover? How is it powered?

Is the Acoustat a stereo amp? You'll want to run the subs in stereo, if possible....

[lpd]

Zilch,
Thanks for the reply. There are ports in the cabs that are 6" X 8" in length. All other holes have been covered. Is the port too big?

I have two outputs on my cd player as well which can be used at the same time (its a McIntosh MCD7007). I used the variable into my pre into the amp for the three way horns. I used the fixed output into the car xo and then into the Acoustat amp to the subs in stereo. I also tried the tape output on the preamp, but the only way I can control the volume of the subs is with the xo levels which aren't very accurate to say the least. I'm powering the xo with an adapter. Any thoughts on the 5234A crossover? I hvae one but the cards I have are 1.1K. Would it suffice or should I look for a 5235?

Thanks

peter

[Zilch]

There are ports in the cabs that are 6" X 8" in length. All other holes have been covered. Is the port too big?6" diameter? Are you sure? 'Cause it looks more like 3" or 4" in this pic:

http://www.lansingheritage.org/images/jbl/specs/home-speakers/1974-l45/page3.jpg

5234A is fine. You need to find or make some 80/100 Hz cards for it. 12 dB/octave would be best. A forum member may be able to provide blank cards for you.

I'd think at this point your problem is the crappy crossover, and the fact that you have no high-pass on the three-way, plus possible phase issues.

Somebody says "Mushy," first thing I think is phase....

[Zilch don't wear no lab coat. Nope. :p ]

[Robh3606]

6" diameter? Are you sure? 'Cause it looks more like 3" or 4" in this pic:

Hello Zilch

You could but a half dozen systems in that cabinet. Depends on the woofer installed as you know.

Hello Peter

Is that a 12V active crossover??? What slopes?? High and low pass ?? You should be able to drop the crossover in between the amps after the preamp just like the 5234 you plan on using. With 100Hz crossover and those woofers in phase you are going to have a good amount of coupling going on if they are staked or close enough to each other. You get coupling and boost around 100Hz and it certainly does muddy things up a bit especially if the crossover doesn't roll off the midbass box. Where does your 100Hz box roll off??? Is the box good to say 60Hz or so?? Where is the F3??? With room loading you may be getting a significant amount of additional extension from that box even if sealed. 12dB could do it, you can certainly try I would look for a set of 18Db cards if the 12dB doesn't work. I know it didn't work for me in my application I ended up using a 24Db network. How are you setting this all up?? You have something to measure it with???

Rob:)

[lpd]

Hello Zilch

You could but a half dozen systems in that cabinet. Depends on the woofer installed as you know.

Hello Peter

Is that a 12V active crossover??? What slopes?? High and low pass ?? You should be able to drop the crossover in between the amps after the preamp just like the 5234 you plan on using. With 100Hz crossover and those woofers in phase you are going to have a good amount of coupling going on if they are staked or close enough to each other. You get coupling and boost around 100Hz and it certainly does muddy things up a bit especially if the crossover doesn't roll off the midbass box. Where does your 100Hz box roll off??? Is the box good to say 60Hz or so?? Where is the F3??? With room loading you may be getting a significant amount of additional extension from that box even if sealed. 12dB could do it, you can certainly try I would look for a set of 18Db cards if the 12dB doesn't work. I know it didn't work for me in my application I ended up using a 24Db network. How are you setting this all up?? You have something to measure it with???

Rob:)

Rob,
It is a 12V crossover, until I find a set of cards for the 5234A or another sub crossover that is more useful. Slopes....not sure about those specs. The room is a rectangle with the three ways on the long wall centered on the wall about 7 feet apart. One sub is on a short wall corner loaded about 16 inches from the back wall and the other is on the same wall as the three ways, but 2 feet on the side of the right three way horn setup. I have the crossover set at 100hz. Three ways are good to about 80 hz I think, but I have no measuring tool to really tell. F3???? Not sure what this is. The midbass horn has a port its like a smaller version of an A7 with a port on top. I plugged the port to remove some of the rolloff/muddiness. Plroblem is I don't have a tool to set it up...any suggestions?

I also moved the one sub on the one corner of the short wall to the otherside which really smoothed things up. Placing two subs is much trickier than I thought...any ideas here?

Cheers,

thanks Zilch/Rob!!!

[Zilch]

You could but a half dozen systems in that cabinet. Depends on the woofer installed as you know.If it's 6" diameter, they're tuned to ~33.5 Hz according to BB6P, i.e., more like 4430, a good tuning for 2235H, of course, but not a sub.

I'd look to installing the 4" diameter tube (ABS pipe here, typically,) inside the present port, or in one of the other holes, preferably in a reversible manner....

[lpd]

I'll check the port and get back to you. Maybe I'm wrong on the measurements. If not I'll try to install a 4 inch one and see what happens.

cheers,

peter

[lpd]

Port is 4" and 9" inches in length. Should I take an inch or two off or leave it as is.

[Zilch]

Leave it. You're tuned to ~23 Hz, good for sub to 75 W, 112 dB @ 30 Hz.

Also, I'm looking up the cards for your crossover, and I find that you'll have to load your own for 100 Hz. The proper component values are in the manual.

The only "standard" one listed for sub is 80 Hz, 18 dB, which I use here myself....

[4313B]

they're tuned to ~33.5 Hz according to BB6P, i.e., more like 4430, a good tuning for 2235H, of course,Some things I just can't sit by and watch transpire. Where is the thumbs down emoticon? I think I've posted at least a dozen times to tune the 2235H in the 28 Hz to 30 Hz range. There's a long history of trying all kinds of volumes and tunings with this driver over the past 26 years and that's pretty much where it all shakes out. Tuning aggressively like the stock 4430 never seems to work real well in the typical room and tuning too low ends up with smacked mass rings and torn suspensions. Of course, feel free to do whatever you want when the day is done.

Have you heard the crack of your mass rings today?

[lpd]

Some things I just can't sit by and watch transpire. Where is the thumbs down emoticon? I think I've posted at least a dozen times to tune the 2235H in the 28 Hz to 30 Hz range. There's a long history of trying all kinds of volumes and tunings with this driver over the past 26 years and that's pretty much where it all shakes out. Tuning aggressively like the stock 4430 never seems to work real well in the typical room and tuning too low ends up with smacked mass rings and torn suspensions. Of course, feel free to do whatever you want when the day is done.

Have you heard the crack of your mass rings today?

Well you can't give me @@$#@ without an explanation of how to tune the 2235 to 28-30hz:D hehe I don't have a clue what to do. I appreciate your thoughts on this.

[4313B]

Here is a pretty easy way for a DIYer to tune a box.

http://www.danmarx.org/audioinnovation/impanalyzer.html

Dan put that article together years ago and it's basically how we had to do it back in the old days when dinosaurs roamed freely and computer time cost big bucks.

You can also pick up http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-802

These techniques should be in any DIYers repertoire. Start simple and read http://www.lansingheritage.org/html/jbl/plans/1979-manual.htm and http://www.lansingheritage.org/html/altec/plans/1974-enc-manual.htm

[hapy._.face]

2235 likes 5 cu ft and 2 ports at 4" ID and 11" in length for an ideal 30Hz-28Hz tuning. Do what you must to work your way into this- those 35's will sound like completely different when you give them this tuning. Believe me- I tried several different ways and got tired of the "one note" BS. 2235's at 30Hz makes them open up and become more...well...muscial. I used old L200 cabs for test beds and I simply added enough internal bracing to offset the volume to equal 5 cu '. I popped in a couple of ports (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=268-352) from parts express (flared 4"ID cut to 11" long) and presto- instant focused bass.

[Zilch]

See line 8 here for 30 Hz tuning of 5 cuft. enclosure:

http://www.jblpro.com/pub/manuals/enclgde.pdf


Any tuning below 27.5 Hz in your 5+ cuft. enclosures, which is where I have my 2235H's similarly aligned and tuned, will require derating of the power handling capacity of the drivers.

Your present 23 Hz tuning cuts it in half, as I indicated above.

You may indeed find that raising the tuning frequency of your bass boxes will alter the total system performance in a desireable manner....

[Mr. Widget]

So we have a pair of 2235s in vented enclosures a pair of midbass horns operating from 100Hz to 500Hz, a pair of compression drivers running from 500Hz to 6KHz and tweeters above that....

There has been a lot of discussion about box tuning... that's fine and can be important but it seems premature to me. I think the discussion should be about system integration and not just focused on the subs... unless your horns are quite large, they would probably be best crossed over at 120Hz or maybe higher. I think with the system you are describing you need to think of the 2235s as woofers and not subs... they should be part of each speaker cluster. If you are not getting good bass out of both speakers you may need to rearrange the room and/or position of the speakers so that you do.

You should buy a crossover that allows you to vary the crossover frequency and ideally the slope too... at the very least you should get one that allows tweaking of the crossover knee as well as frequency. There are several on the market that should get the job done and many that may be had for under $200 on the used market.... in all likelihood they will be of the pro audio or prosumer variety so you may then discover ground loop issues but that will be the discussion for another day.

Sounds like you will be having many hours of fun and frustration ahead.:bouncy:


Widget

[lpd]

See line 8 here for 30 Hz tuning of 5 cuft. enclosure:

http://www.jblpro.com/pub/manuals/enclgde.pdf


Any tuning below 27.5 Hz in your 5+ cuft. enclosures, which is where I have my 2235H's similarly aligned and tuned, will require derating of the power handling capacity of the drivers.

Your present 23 Hz tuning cuts it in half, as I indicated above.

You may indeed find that raising the tuning frequency of your bass boxes will alter the total system performance in a desireable manner....

I'm wondering, rather than adding another four inch port if I could use a single four inch port at 5 inches instead. I suppose at loud volumes it may "chuff" abit, but I'm not a large volume fella. Moving the one 2235 to a different corner really cleaned up the bass, although I'm going to tune the boxes to 30hz, and then pick up a better xo and post my thoughts.

Yes Giskard, lots of frustration, but with each discovery I feel I'm one step closer to the ultimate system. BTW I've tuned the 2235's at 140hz which creates an overlap, but I might experiment with the midbass xo and instead of allowing it to rolloff I'll cut it off. Any thoughts?

[Zilch]

I'm wondering, rather than adding another four inch port if I could use a single four inch port at 5 inches instead. I suppose at loud volumes it may "chuff" abit, but I'm not a large volume fella.Yes, especially O.K. for testing.

With single 4" ports:

27.5 Hz - 5.0"
28 Hz - 4.7"
29 Hz - 4.1"
30 Hz - 3.6"

[4313B]

Any tuning below 27.5 Hz in your 5+ cuft. enclosures, which is where I have my 2235H's similarly aligned and tuned, will require derating of the power handling capacity of the drivers.Unless you apply boost at the tuning frequency of the box. Applying the boost also serves to attenuate response below tuning at a faster rate thereby adding protection to the transducer during unloading. Of course then you have to accept the increased group delay. Nothing is free. If you go with the old 20 Hz tuning and boost there will be a power sag in the 25 Hz region, but tuning and boosting at 25 Hz will handle full rated input as you know since you have a B380.

Yes, especially O.K. for testing.

With single 4" ports:

27.5 Hz - 5.0"
28 Hz - 4.7"
29 Hz - 4.1"
30 Hz - 3.6"All of which should be measured afterwards since we have no clue as to how well you can build a box and minimize losses. Some of those old JBL boxes can have a loss factor around 5 or so. JBL TOTL boxes (250Ti, 4430) are up around 10. Mine usually push 14. (The higher the number the lower the loss, 3 is junk, 7 is typical). Basically cut the ports long to start with just like those old 60's and 70's manuals state. The point is, this stuff really needs to be measured. The math is neato, and BB6P comes surprisingly close consistently well, but if you underbuild or overbuild or use some kind of goofy fill you need to adjust accordingly.

I think with the system you are describing you need to think of the 2235s as woofers and not subs...True. You might even consider pulling those mass rings and going with real subs. Put the resulting 2234H's in smaller boxes tuned higher. They have more kick and are more efficient. As has been posted several times - Mass rings are now "out of favor", 2234H's with EQ are probably the most desirable use of that transducer, 2235H's and 2245H's got beat silly when used as dedicated subwoofers. These concepts are all verifiable by examination.

Yes Giskard, lots of frustrationI think you mean Mr. Widget in this particular instance.

I suppose at loud volumes it may "chuff" abit, but I'm not a large volume fella.Neither am I. The single 4" port has worked for me personally since day one. I never use it for other people though. As for high volume and room response - sometimes people get their woofers placed in a null and start cranking the gain. It might not seem real loud but then an errant tone on some CD or DVD comes along and damage occurs. Point being, watch your cones for physical stress during demanding passages after placing them and be familiar with your source material and it's effects on your system.

[Zilch]

If you go with the old 20 Hz tuning and boost there will be a power sag in the 25 Hz region, but tuning and boosting at 25 Hz will handle full rated input as you know since you have a B380.Indeed, and lpd's 5234A has boost filter capability built-in, at 20 Hz, at least, without modification. We've earlier and elsewhere discussed how to change the frequency of that, but for now, i believe it's beyond the realm of resolving the immediate difficulty.

Regarding which, I view Mr. Widget's observation as critical. The goal of using the 2235H's as subs is an apparent misdirection. What's needed instead is a capable low-frequency system physically integrated with the mids and highs (as opposed to spread around the room,) and additional subs, if then still desired, separately addressed....


The math is neato, and BB6P comes surprisingly close consistently well, but if you underbuild or overbuild or use some kind of goofy fill you need to adjust accordingly.Yes. I'm just posting BB6P calcs here. They should best be viewed as starting points or "guidelines" for experimental determination of final tuning. I currently use Woofer Tester II, plumbers' test plugs, and a calculator for actual cabinet tuning measurement:

http://audioheritage.org/vbulletin/showthread.php?t=10129

[lpd]

Ok guys, I cut down the port size to 4.75 inches and returned to experimental mode. After a few hours of placement attempts I hit the spot. Seems two subs are trickier to place than a single, not sure why. Bass is really smooth, transparent, and the boom is removed. It took a few to get used to as the bottem boom is gone, but its way smoother and easier to listen to. I'm not sure abot measurements, I am borrowing a measuring device from a friend at the end of the month and perhaps I can even improve the situation.

Next is a better XO and power amp for the subs.

Again thanks for the help and the reading material!!!

peter

[4313B]

Seems two subs are trickier to place than a single, not sure why.Me neither. I've never had any problems but we can all pretty much guarantee that someone somewhere is going to have a different experience.

[lpd]

Me neither. I've never had any problems but we can all pretty much guarantee that someone somewhere is going to have a different experience.

Unfortunately I have a room of "node hell" and placing any speaker system in it has been a task. This is my first attempt at a home build/diy. What I did was place one sub and then fine tune for smooth bass easy as pie. The second sub not so easy. Seemed really dry where I had it, but I moved it to another corner and found the perfect placement for it. Bass is strong on both channels and really smooth. Now I'm going fine tune with a xo ect. I have researched that the 5234A is not really recommended for a xo. Will it suffice for subs? How do I calculate parts to build a 100hz card for it?

[4313B]

The biggest problem with the 523x networks is the top end. They're pretty bad for home fi-fi use. They were pretty bad back when they first came out and nothing has changed. The low pass still works for subs. Frankly, you'd be better off ripping the guts out like I do and building a new low pass based on something like the BX63A circuitry. You can add in or leave out the bump filter. I posted all about that at length at one point but it may have been one or two forums ago. Another option would be to build one of Rod's projects in the 523x case. I'm real big on building my own active filters, have been since the early 80's.