I have known Duke LeJeune for quite some time now, even owning his Jazz Module speakers for several years and using his speakers in my exhibit rooms at audio shows. Earl Geddes was his mentor and while Duke manufactures box speakers, he has a pretty good understanding of ESLs having used the original Quad ESL in his research (the speaker that replaced my Jazz Modules) and being one of the more prominent Sound Lab dealers. I think he has a good grasp on sound dispersion and how to maximize it. In addition, I should mention I had never been keen on using subs in my system even though I was well aware of Duke's initial work developing the Swarm.
The last show I exhibited at with Roger Modjeski we used his ESL speakers which by default had to have subs since they only went down to 100 Hz. Roger designed a sub with an 8" driver in a 0.3 cu. ft. sealed box (air resistance) and used two to compliment his panels in a bi-amp set up with the Beveridge RM-3 crossover he designed for the 2SW speakers long ago. After hearing this I followed suit but decided I would expand to 4 subs to replicate the DBA of the Swarm. For the last few years I have enjoyed this set up with both the Quad ESL and now my modified Acoustat Model 2 speakers.
However, I was intrigued enough by mijostyn's set up that I contacted him and he sent me a photo so I could visualize it. I would like to add that I was not unhappy with my DBA set up, but since he was also using Acoustats (they are essentially a bigger version of my Model 2s) I felt this was worth a try. Over the past few days we have been communicating and he has helped me tweak things to get the set up just right. I have been listening on and off since last evening and have to say I am impressed by what I hear, the primary difference being what I feel in the low end. So I would like to thank mijostyn for his contributions to this topic and help getting me there. I will try to post more on this as I continue my listening.
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My subs were built a while back, mijostyn helped me set them up for optimal performance in the line array. His subs have quite a large footprint, as do his speakers which are probably the best Acoustat model in my opinion. They line array per mijostyn is actually a semi circle as opposed to all of the subs being against the front wall of the room. A very interesting set up and one that does require some attention to detail. I appreciate mijostyn’s patient with me.
In my room the DBA did work well for my needs, and it wasn’t a difficult system to set up. My only nit was that my room constraints didn’t allow me complete freedom to place the subs anywhere I wanted. The sound was quite good though. I am embarking on building 4 new subs using a 10" driver and look forward to going to the audio show in Long Beach to hear Duke’s Swarm in person. |
I use low pass and high pass filters in my active crossover, Linkwitz-Riley 4th order 24 dB slope. One reason this was chosen is that we wanted to keep deep male vocals out of the subs. The other reason had to do with the resonance of the 8" drivers which we wanted to keep above 100 Hz. This is the reason for a 0.3 cu. ft. box which is stuffed tightly with cotton batting. The last reason has more to do with Roger Modjeski’s ESL design which only goes down to 100 Hz but that is irrelevant to me as I use the Acoustats which he modified to create greater dispersion, but left the rest alone, sort of ;)
I should also mention that the speakers are 4 ft. from the wall behind them, 18" from the side walls, and about 94" apart, which is the same distance to my listening position.
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@noble100 if it wasn’t clear let me try to clarify it for you.
1. I’m building subs with 10" drivers for use as either a DBA or line array. It’s nice to have choices.
2. My active crossover has LP and HP filters set at 100 Hz. So the HP output sends signals 100 Hz and above to the panels and the LP output sends signals below 100 Hz to the 4 subs. Direct drive amps power the panels, a solid state amp or moderately powered tube amp with good damping powers the subs.
3. My current subs use 8" drivers in a tightly stuffed 0.3 cu. ft. box. This was done to insure the resonance of the driver was above 100 Hz. If I set the crossover points to 150 Hz on my filters this would be an issue but since I’m using 100 Hz and anything below that is sent to the subs this falls below the resonance so it’s a good thing. I should note that this was designed by Roger Modjeski for his ESL speaker system and the subs easily extend down to 30 Hz. If you don’t know who Roger is look him up, his experience and reputation speak for itself.
I tend to think at this point you just might have an issue with anyone who isn’t completely devoted to the DBA as you are. At least I can say from experience I have used the DBA and now trying a line array I have the ability to compare and decide what works best for me. My comments regarding Duke have more to do with my respect for him as a speaker designer, having owned his speakers at one time and exhibited his speakers at shows, than anything to do with DBA. Anytime I am at an audio show and Duke is exhibiting I make sure to spend time visiting the room. It’s always interesting to see what he is up to.
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@mijostyn, I'll have to send you a photo showing what Roger did to create the wider dispersion. It basically involves some resistors, I believe three of them mounted near the bottom of the panel. I had to snip some of the wiring to put them in.
Roger felt that the Model 2, 3, X, and 2 + 2 designs were very good. So in designing his ESL panels he utilized the Acoustat panel material, as well as what he learned from Harold Beveridge and his own research to come up with his design. One thing Roger did not want was a big ESL, so it has a small footprint which means it's not very efficient, maybe 80 dB, and it doesn't go low, 100 Hz. He also did not want to mess with curved panels, so his are flat. His idea was to create a system made for bi-amping using his own direct drive amps and a solid state amp he would design with built in crossover (in our systems we both use the Beveridge RM-3 but given those are pretty unobtanium that would not be feasible for consumer sales). Roger much preferred the subs not be part of the panel structure, so they could be placed around the room, much like a DBA. He uses only 2 in his system.
My Acoustat Model 2s have slightly angled panels, that come to a peak in the front middle of the speaker and angle back from there. The panel sizes are the same as your 2+2 I believe. On each speaker one of the panels was removed and replaced with one of Roger's from an early prototype of his speaker which had the same exact size panel. The other panel is stock. I can set the speakers up so Roger's panel is on the inside or outside (which is how I have it now) and I have definitely noticed a difference in imaging when swapping positions.
As a side note I just got my Atma-Sphere system set up again today and at some point I will probably bring out my Quad ESL 57 to use with the M60 amps. I like this combination as well, although I don't think the line array will work with 57s, so I'll probably go back to a DBA.
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@noble100, The amplifier is the Music Reference RM-200, 100 watts per channel, damping factor of 10, can drive a 2 ohm load (it’s a favorite amp among some of the Martin Logan crowd). The other amps I use are vintage Luxman and Accuphase amps. For solid state I don’t bother with Class D, was never consumed with mega watts, and much prefer a high current Class AB design which is more suited to my needs. Also, the 8" drivers I use don’t need much in the way of damping.
As for my subs being feeble, sure no problem, we all have our opinions. Glad I could amuse you. However, I don’t listen to my music loud, I don’t do HT, and I’m not consumed with the last octave in the bass. As I mentioned, the system was designed by Roger Modjeski and his reputation speaks for itself. The cabinets for the 10" drivers are going to be a unique design and the bass will extend lower, but again, bass has never been the primary focus for me. My set up does exactly what I need it to do and so far it’s doing it better as a line array than the DBA. Although I find both set ups to be very useful in creating smooth, fast, and un-smeared bass.
BTW - I hope you are not using that Dayton Audio kilowatt amp for your swarm.
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@noble100, my speakers are the Model 2, mijostyn has the 2+2. I doubt my speakers go down to 28 Hz, but regardless I am cutting them off at 100 Hz. IIRC I think Duke recommends running the mains full range and set the frequency on the Swarm accordingly. If I am wrong about that I apologize to him in advance. I could run my system that way, but I prefer to follow Roger's method and treat the panels as if they were designed to only go down to 100 Hz.
As for your amp, measure it. That will tell you what you need to know.
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@bdp24, the Beveridge amps were not Roger's design, only the RM-1, RM-2, and RM-3 which mad up the rest of the components in the Beveridge system which if I recall was the 2SW.
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@mijostyn, yes that includes the direct drive amps and bass amp with active crossover. As for why it's not on the website the main reason that Roger doesn't have the time to bother with it.
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@bdp, thanks for pointing that out and sorry the mistake. The DD amps are extra. If purchased without the DD amps a separate power supply for the panels is included for use with other amplifiers.
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The DD amps are not designed after the Acoustats other than they provide the requisite voltage to the panels. A while back Roger designed a drop in board for the Acoustat amp that used 3 x 6DJ8/6922 for a tube input. IIRC his amps also use this input, but he also designed a different output. The ESL is a single flat panel designed for wider dispersion than other panels of this type. I am not sure of the measurements but it has a small footprint. If I had to guess it is 40" tall by 18" wide. Roger does use the panels and amps in his system with an active crossover and two bass speakers.
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