[Wind Chaser]

Compared to what?

[OzarkTom]

Compared to what?

Compared to the Acoustats driven by the 5000V DD OTL tube servo amps. They sounded like a heavy blanket was taken off of the speakers when you bypassed the medallion transformers and used DD OTL tube amps. Also, much better bass and dynamics, night and day difference.

[Wind Chaser]

I knew Acoustat made an amp called the Transnova, apart from that, I wasn't aware that there were other amps available under the Acoustat brand.

Haven't heard a OTL let alone a "DD OTL",  how are they different?

[OzarkTom]

These 5000 volt OTL tube amps drove these speakers direct, no need for transformers. Quads has transformers, they also sound much better with DD OTL tube amps.

Since I was an Acoustat dealer, I tried every amp I could gtt my hands on. I tried OTL Futtermans, Quicksilvers, Moscodes, Transnova amps, Conrad Johnson, Audio Research, Classe, Rowland, and many others. None of those came even close to the DD OTL tube amps.

If you have a bucket list of systems to buy or listen to, you should put these Acoustats at the top of your list. The X's were first brought out in 1978.

[Wind Chaser]

Still don't understand what makes a direct drive different from a non DD amp, but are DD amps made specifically for stats or can they be used with any kind of loudspeaker?

[OzarkTom]

Acousta'ts DD OTL amps only works with Acoustats, I believe Roger Modjeski will make OTL amps for any ESL's you want to use for about 5-6K. Here is a interesting history of Beveridge and Roger Modjeski.

http://bevaudio.com/history.html

note: I sold three used pairs of these Acoustats back in the early 80's , and all three are still using these today. That is how good they are.

[JohnR]

Wrt to the OP/thread title, I suspect that geometry is at play here. A "short line" will be partly in the near field and partly in the far field at normal listening distances.

[neobop]

Still don't understand what makes a direct drive different from a non DD amp, but are DD amps made specifically for stats or can they be used with any kind of loudspeaker?

Electrostatic panels have a high voltage charge.  The signal from the amp effects the charge - makes the diaphragm move.  Conventionally driven stats have transformers which plug into the wall.  Direct drive amps supply the high voltage charge which is 5KV for Acoustats.

In the late '80s I had 2 panel Acoustats with DD amps modified by Dan Fanny of American Hybrid Technology.  He designed the boards and they each had 4 big high voltage cap tubes and banks of storage caps.  Those amps had some slam.  In general, full range stats can sound thinner because the have no box and bass reinforcement is totally room dependent.   Even with big panel stats you might not get as much warmth as with conventional speakers or slower planer type panels.
neo

[BruceSB]

The lack of slam, and, in the case of the JansZens ease of placement, is one of the reasons why some manufacturers are making hybrid speakers.
Sanders, JansZen, and of course, Martin Logan.
As an aside I had a couple of extended listening sessions to the only Martin Logan full range, the CLS.
Boy was that a great speaker!!
I understand that David Janszen claims very high db levels for his hybrid electrostats.
Bruce

[Wind Chaser]

Electrostatic panels have a high voltage charge.  The signal from the amp effects the charge - makes the diaphragm move.  Conventionally driven stats have transformers which plug into the wall.  Direct drive amps supply the high voltage charge which is 5KV for Acoustats.

Okay, that makes sense. Thanks for the concise explanation.

In the late '80s I had 2 panel Acoustats with DD amps modified by Dan Fanny of American Hybrid Technology.  He designed the boards and they each had 4 big high voltage cap tubes and banks of storage caps.  Those amps had some slam.  In general, full range stats can sound thinner because the have no box and bass reinforcement is totally room dependent.   Even with big panel stats you might not get as much warmth as with conventional speakers or slower planer type panels.

About 1982-1983, I had the Model Two. And as you say, they are very room dependant. I had terrific bass down to about the mid-thirties, but slam isn't a word I would use to describe them. Have you ever tried listening to the Sheffield Drum Record with Acoustats?

[lowtech]

Yep, very, very veiled. I was the fifth largest Acoustat dealer back in 1982-83.

I was in the top 10 and personally owned model 2's for about 15 years.  Wouldn't exactly described them as being veiled, let alone "very, very" so, but they could sound that way when powered by poorly matched (tube) amps or when not setup well or used in rooms with overly damped rear walls.

Never cared for any of the "plus" stacked versions.  All things considered they did have excellent bass response IMO.

[neobop]

About 1982-1983, I had the Model Two. And as you say, they are very room dependant. I had terrific bass down to about the mid-thirties, but slam isn't a word I would use to describe them. Have you ever tried listening to the Sheffield Drum Record with Acoustats?

Never listened to demo records at home.  I had enough of that at work, but my buddy Dan Fanny who I mentioned previously, had 2 + 2's and amps slightly more tricked-out than mine.  He had many of those demo records and a nice classical collection to play on his Goldmund Reference table.  There was no lack of dynamics or slam.  Detail and harmonic integrity were first rate, although they didn't image like a good dynamic speaker. 

Stats present a weird load to an amp and not all amps are suitable.  The impedance of the panels drops as the frequency increases.  This is the opposite of conventional speakers.   DD stats are really the way to go, especially with full range panels.  On the other hand, the most musically impressive system I've heard was a tri-amp system with 2 Acoustat panels with wall warts, as midranges.  The panels were driven by Rowland monoblocks.  There was an Infinity EMIT tweeter in the middle of each panel pair.  They were driven by a 30 watt Berning.   Deep bass was handled by 2 large Entec woofers with an Audio Control Richter scale crossover/equalizer.  Panels had no high pass filter - driven full range in the bass.   

This system was the brain child of Dr Marty Wax and was astoundingly real sounding.   Ever hear music coming from another room and thought it was live when it was actually a recording?  Stats are the only speakers that could do this for me on a rare occasion.

neo

[smk]

Not sure exactly what you mean by "thin." Full panel panel speakers are dipoles & need to be placed properly in regards to boundaries. But with  the right amp, can sound magical.

The only problem I have is psychological. The sound appears to come from a large area. In other words, a guitar, for instance, appears larger than life. And then they dominate the room.

[OzarkTom]

I was in the top 10 and personally owned model 2's for about 15 years.  Wouldn't exactly described them as being veiled, let alone "very, very" so, but they could sound that way when powered by poorly matched (tube) amps or when not setup well or used in rooms with overly damped rear walls.

Never cared for any of the "plus" stacked versions.  All things considered they did have excellent bass response IMO.

Just very, very compared to the DD servo amps. You have to hear it to believe it.

Did Jim Strickland ever fly up to your shop?

[Wind Chaser]

Never listened to demo records at home.

The drum record was NOT a demo record, much less a normal record, but a (stress) test record. Each side was only about 6 or 7 minutes in length as the grooves were considerably wider and deeper than a normal recording. My Acoustats could handle any normal garden variety drum recording, but they utterly crapped out with the Sheffield test record.

Would they have faired any better with a DD amp? Maybe, maybe not.

[OzarkTom]

The drum record was NOT a demo record, much less a normal record, but a (stress) test record. Each side was only about 6 or 7 minutes in length as the grooves were considerably wider and deeper than a normal recording. My Acoustats could handle any normal garden variety drum recording, but they utterly crapped out with the Sheffield test record.

Would they have faired any better with a DD amp? Maybe, maybe not.

I had that Sheffield record, I never had or sold any system that would play it correctly.

One big advantage the DD Acoustats have, no speaker cables. Some AC'ers spends thousands just on speaker cables. I would love to hear these with a top end DAC with remote volume control today.

[lowtech]

Did Jim Strickland ever fly up to your shop?

No, but a few of us flew down to visit the factory.  We were the world's largest Vandersteen dealer at the time, so the number of Acoustats that went out the door was small potatoes (although that's what I owned).  Richard would drop by the store every so often.  What a character.

For those still discussing why electrostatic's sound "thin" - the full range ones are dipole radiators, don't pressurize the room and excite far fewer room modes.  All good things.

[Wind Chaser]

I had that Sheffield record, I never had or sold any system that would play it correctly.

What do you mean by correctly?

I also had a pair of Maggie's at the time. Compared to the Acoustats, they had no problem. It seemed to me as though the diaphragm on the Acoustats was being pushed too hard, as though it reached the limit of its X-max given the noise they made.

[OzarkTom]

What do you mean by correctly?

Without any distortion, amp or speakers maxxing to the limit.

[jsm71]

Thanks for the replies--I certainly have a lot of food for thought! Any sane person would be perfectly happy with my current speakers! I just hate that nagging sense of "is there something better out there?"  I am somewhat limited by speaker placement--MLs could not be as far away from the wall as optimal. My DALIs seem less fussy, and they are certainly clear and musical. That should suffice!

ESLs don't have to sound thin if they are big enough to support low frequencies or if they effectively manage the challenge of hybrid designs mating woofers with the panel.  I am a JansZen owner and they have the frequency balance issue solved perfectly, arguably one of the best hybrid designs available.  They also solve the room placement problems inherent with all dipole designs.  I was a Maggie 1.7 owner before buying the JansZens.  They took away all the room placement and power requirements the Maggies demanded, and are also an easy load for tube amps.