JBL L-200 upgrade

[macrojack]

http://www.audiocircle.com/gallery/albums/userpics/50520/horns_010.jpg


This was easy even for a guy like me with eleven thumbs. :applaud:

[macrojack]

Because I am low tech, I couldn't figure out how to post anything more about my project above, so I am continuing here.

The picture above shows AH300 horns with B&C DCX drivers mounted via a steel bracket to the back of my JBL L-200. To accomplish this I bypassed the crossover and the horn inside the JBL and used a dbx Drive Rack PA to actively divide between a Rowland 102 on the horns and a Perreaux PMF 1850 on the LE 15B woofers.

I am not presently using the tweeters in my DCX, so this is just a 2-way. Response seems to be very even between about 50 HZ and 14 Khz.

Any comments or suggestions would be appreciated.

[hjames]

Because I am low tech, I couldn't figure out how to post anything more about my project above, so I am continuing here.

The picture above shows AH300

Any comments or suggestions would be appreciated.

Sorry, no such luck, the only picture you got posted is the menubar header from some other Audio website ...
I went there and tried to search for L-200 but just got a bunch of other stuff - plus that site is S L O W ... no luck ...



AH300 horns with B&C DCX drivers mounted via a steel bracket to the back of my JBL L-200. To accomplish this I bypassed the crossover and the horn inside the JBL and used a dbx Drive Rack PA to actively divide between a Rowland 102 on the horns and a Perreaux PMF 1850 on the LE 15B woofers.

I am not presently using the tweeters in my DCX, so this is just a 2-way. Response seems to be very even between about 50 HZ and 14 Khz.


Yeah, I did the usual upgrade of adding a JBL 2405 slot tweeter to mine and rebuilding the passive crossover. I also pulled the LE15 and replaced it with a 2234 woofer (newer 15 inch)
I'm currently preparing to drill out the back of the cabinet and add an external "bump-out" t the back of the cabinet so I can swap out the original 2307 horn for the longer 2312 that came with the 4333 & L-300 speakers.

Be interested if you could save your pictures to your your desktop then copy them to the site here ... like to see what your project looks like ...

[macrojack]

I bookmarked the thread when I posted it and when I went back there just now, my photo is showing.

If you go to the link here: http://www.acoustichorn.com/news/index.php?published-max=2008-12-24T15%3A35%3A00.001-08%3A00

You can find pictures under "Tom from Denver". I live about 250 miles from Denver so I'm not too sure why it's listed that way.

My approach wasn't too expensive by high end horn standards and it did not require modifying the cabinet aside from 4 small screw holes in each.

[hjames]

I bookmarked the thread when I posted it and when I went back there just now, my photo is showing.

If you go to the link here: http://www.acoustichorn.com/news/index.php?published-max=2008-12-24T15%3A35%3A00.001-08%3A00

You can find pictures under "Tom from Denver". I live about 250 miles from Denver so I'm not too sure why it's listed that way.

My approach wasn't too expensive by high end horn standards and it did not require modifying the cabinet aside from 4 small screw holes in each.

Gorgeous wood horns - thanks for the effort chasing them down for the post!
I grabbed and resized the room-view picture here - hopefully thats ok? Let me know otherwise!
And thanks for sharing - they are very cool!

[Mr. Widget]

Nice work... I doubt it would make it past the wife though. :(


Widget

[macrojack]

Thanks for the comments. I have a wife who doesn't really mind as long as the speakers stay back against the wall.

They really aren't all that obtrusive. The top edge of the cherry horn is only about 52 inches off the floor.

I read somewhere on this site that the abiding weakness of the L-200 was the lack of a tweeter and the smallness of the horn. Since I already had the speakers, I looked for ways to take advantage of an excellent cabinet and driver by overcoming the other inadequacies. When I started talking to Bill Woods, everything fell together.

[toddalin]

I looked for ways to take advantage of an excellent cabinet


??? :o:

[hjames]

Interesting approach!
I came to this site for research, and when I read all the positive feedback on the L-300 and similar design big box 3-ways
I decided to follow the path others here had taken ... building a new passive crossover with more modern design,
adding the slot tweeter like many of the pro Monitors used, and now preparing to upgrade to a longer horn that
will cross over better at lower freqs.
Of course the best upgrade is biamping - but I don't want that much complexity in my living room.
(My other 4 way system is biamped).

See SubWoof's upgrade guide here -
http://audioheritage.org/vbulletin/showthread.php?t=20349&page=2


Thanks for the comments. I have a wife who doesn't really mind as long as the speakers stay back against the wall.

They really aren't all that obtrusive. The top edge of the cherry horn is only about 52 inches off the floor.

I read somewhere on this site that the abiding weakness of the L-200 was the lack of a tweeter and the smallness of the horn. Since I already had the speakers, I looked for ways to take advantage of an excellent cabinet and driver by overcoming the other inadequacies. When I started talking to Bill Woods, everything fell together.

[macrojack]

I didn't even want to think about cutting so I just left the LE-85/horn where it was and added the big horn to the top. Bill Woods did the cyphering for me using the same woofer and cabinet volume and my very same horns and drivers. Low pass for thr horn is 400 Hz @ 24 db LR and the woofer drops out around 900 Hz and I forget the slope I used there but I can check if you are interested. There is a little additional tailoring and, of course, compensation for a 16 db efficiency differential.

Before I went to bi-amping, I used the native crossover in the L-200 straight to the AH 300 and it sounded very good. This is the best mid-range I have ever heard anywhere. Crystal clear and undistorted.

An important consideration in this is the dispersion of the AH 300. It is only 40 degrees wide (20 degrees off axis). For me, this works fine but many people might find it too limited.

I would suggest that you talk to Bill Woods before you cut. He's really an artist. He reminds me of a Gepetto sort of craftsman tucked away in his workshop in the Canadian woods.

He recommended the B&C drivers to me because he says they are the best sounding drivers available but he will create adaptors for any driver you want to use as part of the deal.

Doing business with me was probably not his preferred route as I am basically a plug and play person but you DIY people are why he is in business.

http://www.acoustichorn.com/products/300/index.html

I bought into this sight unseen because of who else was using these horns. It seemed obvious that they must be top tier. I like the retro look a lot too.

[toddalin]

I didn't even want to think about cutting.

Ahhh, where's the fun in that? Here's what I did.

Three 2312s (L,C,R) prepared for install. All horns were treated to 11 oz of a spray-on rubber coating to deaden inherent resonances.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build013.jpg

A template was made to gauge the size and placement of the hole.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build003.jpg

Cabinet is taped up, hole is laid out and cabinet is cut open.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build004.jpg

No turning back now!

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build005.jpg

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build006.jpg

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build007.jpg

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build010.jpg

The "wart" was made of 1-1/2" x 1-1/2" with a 5/8" piece of high density shelving board.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/index_002.jpg

Done:

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/H92_The_Build011.jpg

Of course the crossovers (home-made) were tweaked to take advantage of the new components.
http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Crossover3.jpg

[macrojack]

Todd,

Very impressive - you do nice work.

I don't like to do craftsman stuff and hesitated to even show up on this site.

But ......... I figured my speakers were sort of a DIY deal since you can't just order a pair from Audio Advisor. And I surmised that since they have a JBL at their core, they might prove interesting to readers here.

If Bill Woods is correct, JBL never made a horn or a driver that can run with these. Check them out.

Tom

[jerry_rig]

I have to ask each of you if you notice any issues with respect to time alignment. I risk getting flamed here, but those long horns sitting way back there have to be out of sync with the rest of the system. (If you are using the DriveRack, you should be able to adjust for this.) The reason I ask is that I am working on a Smith horn DIY system and I would like to know if it is an issue.

The other day, I listened to a $170K Wilson Audio Alexandria speaker system. One of the selling points is the positioning of drivers for optimal time alignment. Needless to say, it sounded amazing. When commenting on this, the salesman claimed that, by fixing the time alignment problem, your brain "doesn't have to work so hard" when processing the music signal. It made some sense, but the topic is not given much treatment here.

[4313B]

I have to ask each of you if you notice any issues with respect to time alignment.Different types of listeners. Some people just flat out don't care.

[demon]

I have to ask each of you if you notice any issues with respect to time alignment. I risk getting flamed here, but those long horns sitting way back there have to be out of sync with the rest of the system. (If you are using the DriveRack, you should be able to adjust for this.) The reason I ask is that I am working on a Smith horn DIY system and I would like to know if it is an issue.since i have a very long horn and a very digital conrol unit i tried my best to time allign all three ways (soon will be four).
i really took some time to get it all right and when i was done the rig sounded like it had "sat down".
so i think i can hear it -could be just a rewarding function of my mind, though.
anyway, if you can easily manage to time allign, nothing speaks against it.

cheers,
mikey


edit:
oh yeah, and tom (macrojack): your speakers loo very nice! i bet they sound as good, too?
cheers, have fun!

[macrojack]

I wondered about that time-alignment issue myself. And I found this tool:

http://www.mcsquared.com/wavelength.htm

I have to estimate this number but my horn diaphragm is about 16 to 18 inches behind my woofer dustcap. At 400 HZ. (my X/O point) the wavelength is about 34 inches. That means that my drivers should be 180 degrees out of phase. I can't hear that but it might be one of those problems you aren't aware of until it is solved.

It is true that this can be solved with my Drive Rack but I first have to figure out how.

I have a more annoying problem I would like to overcome. There is a low level hiss emitting from all 4 drivers whenever the amps are running. This occurs even when the preamp (JRDG Capri) is muted and it is not affected by the volume control when the mute is off. Any ideas?

I suspect it has something to do with my amplifier gain settings but I don't really understand how that works. My Rowland amp is 100 watts per channel (ICE power) and my woofer amp is 180 watt Perreaux. At my listening levels on pre-recorded music and movies, I can't imagine that clipping would be an issue, and indeed signal barely shows on my Drive Rack meters. This is apparently what amplifier level matching is supposed to prevent.

The Drive Rack is designed for live professional sound reinforcment applications and has many feayures I just don't need like feedback supression. Maybe the amp level matching falls into that category. Does it?

Thanks for the compliments. I'm from the high end audio world and have been used to much less performance for a lot more money. This project cost me just over $4K total including the Drive Rack, the second amp, and wire and connectors. And it is way more fun and exciting than prescribed, off the shelf packages.

[hjames]

Such hissing sounds like a noise floor issue ... your preamp feeds the dbx Drive rack, then that feeds the Perreaux and Rowland amps?

Do you have the hissing when the dbx is powered down? (not just bypassed but actually out of the circuit).
The dbx gear is a step above behringer, but its still lower end pro gear ... and that could be your noise ...
Have you tried using a higher end electronic crossover?
instead of the dbx Drive Rack PA, maybe upgrade to an Ashley (I use an XR 1001) or perhaps one of the Marchand units?

If you are talking about a driver being 180 degrees out of phase, thats easily cured by swapping the + and - leads to that driver - it was recommended that I do that for the 2235 woofer that runs on the low-side of my active split on my 4341s 4 ways). Made a difference in my system. Better to do that fix discretely than to do it digitally, if its 180 degrees out.


... my drivers should be 180 degrees out of phase. I can't hear that but it might be one of those problems you aren't aware of until it is solved ...

I have a more annoying problem I would like to overcome. There is a low level hiss emitting from all 4 drivers whenever the amps are running. This occurs even when the preamp (JRDG Capri) is muted and it is not affected by the volume control when the mute is off. Any ideas?

I suspect it has something to do with my amplifier gain settings but I don't really understand how that works. My Rowland amp is 100 watts per channel (ICE power) and my woofer amp is 180 watt Perreaux. At my listening levels on pre-recorded music and movies, I can't imagine that clipping would be an issue, and indeed signal barely shows on my Drive Rack meters. This is apparently what amplifier level matching is supposed to prevent.

The Drive Rack is designed for live professional sound reinforcement applications and has many features I just don't need like feedback suppression. Maybe the amp level matching falls into that category. Does it?

Thanks for the compliments. I'm from the high end audio world and have been used to much less performance for a lot more money. This project cost me just over $4K total including the Drive Rack, the second amp, and wire and connectors. And it is way more fun and exciting than prescribed, off the shelf packages.

[macrojack]

hjames - I'll try those experiments. Thank you.

Are my calculations re: the phase issue correct? It seems like the 180 out of phase is too easy and too convenient.

Then again, I'm not sure I'll even hear it. Will report back after testing.

The dbx unit provides more than XO. I bought the matching microphone and I find the RTA works pretty well. I also use the EQ functions as well as I can.
Aside from being a computer, which is to say incompatible with my aging brain, the dbx is quite comprehensive and convenient ..... and maybe noisy.

Would I be better off with a well-designed passive crossover?

[hjames]

I tend to think once you've gone to the hassles of biamping that you'd never be happy giving up the advantage of having the woofer directly coupled to a high quality amp with no passives to interfere with the sound.

There are folks here who use Behringer and dbx RTAs for the digital tweaking capabilities they provide - but there is that trade-off with them having a heightened noise floor. Some folks use RTAs just as tools to check and see how their system is prforming, then they power it down and pull it offline for normal sound use. What works great for PA and commercial sound reinforcement use can be far too noisy for home use.



hjames - I'll try those experiments. Thank you.

Are my calculations re: the phase issue correct? It seems like the 180 out of phase is too easy and too convenient.

Then again, I'm not sure I'll even hear it. Will report back after testing.

The dbx unit provides more than XO. I bought the matching microphone and I find the RTA works pretty well. I also use the EQ functions as well as I can.
Aside from being a computer, which is to say incompatible with my aging brain, the dbx is quite comprehensive and convenient ..... and maybe noisy.

Would I be better off with a well-designed passive crossover?

[toddalin]

I wondered about that time-alignment issue myself. And I found this tool:

http://www.mcsquared.com/wavelength.htm

I have to estimate this number but my horn diaphragm is about 16 to 18 inches behind my woofer dustcap. At 400 HZ. (my X/O point) the wavelength is about 34 inches. That means that my drivers should be 180 degrees out of phase. I can't hear that but it might be one of those problems you aren't aware of until it is solved.

It is true that this can be solved with my Drive Rack but I first have to figure out how.

I have a more annoying problem I would like to overcome. There is a low level hiss emitting from all 4 drivers whenever the amps are running. This occurs even when the preamp (JRDG Capri) is muted and it is not affected by the volume control when the mute is off. Any ideas?

I suspect it has something to do with my amplifier gain settings but I don't really understand how that works. My Rowland amp is 100 watts per channel (ICE power) and my woofer amp is 180 watt Perreaux. At my listening levels on pre-recorded music and movies, I can't imagine that clipping would be an issue, and indeed signal barely shows on my Drive Rack meters. This is apparently what amplifier level matching is supposed to prevent.

The Drive Rack is designed for live professional sound reinforcment applications and has many feayures I just don't need like feedback supression. Maybe the amp level matching falls into that category. Does it?

Thanks for the compliments. I'm from the high end audio world and have been used to much less performance for a lot more money. This project cost me just over $4K total including the Drive Rack, the second amp, and wire and connectors. And it is way more fun and exciting than prescribed, off the shelf packages.


If your "Rowland" is really a "Roland," that could be your problem.

If you have RTA capabilities, this would be the preferable way to set your speaker component phasing. Check it both ways and see which provides the overall smoothest response. Forget about one frequency as the levels of some will come up while others go down.

I initially used to use a tone at the ~crossover frequency and use a sound level meter to determine which way was louder with the rationale that the louder setting would mean that the two speakers were in proper phase.

Well yes and no. :o: Often this frequency could be louder, but other neighboring frequencies could be worse. Once I got the Behringer with the 62 bands of RTA, it was easy to see the error of my ways and now I look for the smoothest overall response.

[macrojack]

Todd - This is my amp and preamp: http://www.jeffrowland.com/CapriWith102-front.htm

I know for a fact that JRDG is among the quietest equipment on the market. It's fully balanced, dual mono and very well shielded. The chassis are made from a hollowed out aluminum billet.

hjames - My noise floor is pretty quiet. It doesn't interfere with program material at all. It's really quite faint even with my head in the horn. It reminds me of putting a seashell up to my ear - sounds like the ocean.

It's just audiophile anality that drives me to try and eliminate it. Oh yeah, my wife complains about it a little too.

By the way, you were right. It is coming from the dbx.

[macrojack]

Just out of curiosity, since my dbx is noisy, where's a brother to look for digital devices like the Drive Rack PA that will not be noisy. I've seen the words "a lot more money" used to describe the upgrade. So what brands might I investigate (dream about) and what do they cost?

And will I still find that analogue is better?

In my world, no kind of digital playback quite does what an LP can do.

[hjames]

Just out of curiosity, since my dbx is noisy, where's a brother to look for digital devices like the Drive Rack PA that will not be noisy. I've seen the words "a lot more money" used to describe the upgrade. So what brands might I investigate (dream about) and what do they cost?

And will I still find that analogue is better?

In my world, no kind of digital playback quite does what an LP can do.

Well, my decision to go with an Ashly crossover was based in no small part on the discussion here - http://audioheritage.org/vbulletin/showthread.php?t=2316&page=9

Of course, that discussion started in 2004 and many of them have moved on to even better gear since then, but being on a budget, a used Ashly worked way better for me than a used JBL M552 had ...