[Crossoverless]

Maybe Ben Peters is bringing back a improved version of his Audiostatic/Threshold ES-500 Electrostatic speakers...

http://www.hometheaterhifi.com/volume_5_2/thresholdes500.html

[Dracule1]

Ben Peters newest design is based off of his former Audiostatic ES-500....more info in this thread below.

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1374183292

Freq response 20 Hz +-3dB from an extrostat about the size of magnaplanar 3.7?  When can we start laughing  .

[MtnHam]

Freq response 20 Hz +-3dB from an extrostat about the size of magnaplanar 3.7?  When can we start laughing  .

Now. This is, at best, a joke, more likely a scam. It just doesn't seem likely. Let them prove it with credible tests and/or listening opportunities. Until then, I remain a skeptic.

[BruceSB]

My guess is that the trade-off is that it only plays very very quiet!!
Well, as everyone else is saying someone needs to hear them!
Bruce

[Dracule1]

My guess is that the trade-off is that it only plays very very quiet!!
Well, as everyone else is saying someone needs to hear them!
Bruce

Precisely! At what level?  The designer has claimed some outrageous specs with his speakers in the past. 

[Dracule1]

Now. This is, at best, a joke, more likely a scam. It just doesn't seem likely. Let them prove it with credible tests and/or listening opportunities. Until then, I remain a skeptic.

Even the largest SoundLabs have hard time reaching that low, if at all.

[Hank]

Even the largest SoundLabs have hard time reaching that low, if at all.

That's a sobering thought.  Then these new little 'stats must be defying a law of physics. 

[Crossoverless]

Freq response 20 Hz +-3dB from an extrostat about the size of magnaplanar 3.7?  When can we start laughing  .

 I don't think 20 Hz +-3dB can be done with a Electrostatic speaker... no matter what size the panel is!... If someone does some tests on these new Audiostatic Electrostatic speakers, I will be shocked if they come even close to 35 Hz !!

[Crossoverless]

I was looking on Essence web site and everything has changed now. Audiostatic is now selling a much smaller panel that only goes down to 60 Hz +-3dB and cost $2160 a pair! Maybe they will sell their larger panels that go down to 20 Hz later on at a higher price!

http://www.essenceelectrostatic.com/new-audiostatic-electrostats-need-no-ac-power/

[Hank]

That's the same drawing that is WAY out of perspective.  Text states 48" tall x 9.5" wide.  That drawing has the width looking about 2/3 the height dimension.
Expensive for such a small panel.

[Dracule1]

I was looking on Essence web site and everything has changed now. Audiostatic is now selling a much smaller panel that only goes down to 60 Hz +-3dB and cost $2160 a pair! Maybe they will sell their larger panels that go down to 20 Hz later on at a higher price!

http://www.essenceelectrostatic.com/new-audiostatic-electrostats-need-no-ac-power/

The 20 Hz +-3 spec was for their discontinued ES500 speaker.

[Jazzman53]

I don't think 20 Hz +-3dB can be done with a Electrostatic speaker... no matter what size the panel is!... If someone does some tests on these new Audiostatic Electrostatic speakers, I will be shocked if they come even close to 35 Hz !!

I find that claim suspect too.       

[Russell Dawkins]

I don't know of any technical reason why an electrostatic speaker can't get down to 20Hz, except for the enormous area it would need to have any output at that frequency - but that's largely a function of the front-to-back cancellation of a dipole and the limited excursion potential. The former would be taken care of by a sealed box, but that's not unheard of - Janszen does it, although not at bass frequencies. I also seem to recall a French subwoofer that was electrostatic—or, at least planar—but I cannot find reference to it.
 
What I would like to see (or hear) would be an electrostatic sub in a configuration like a ripole but with multiple folds, like a Heil air motion transformer, but huge. It might move enough air to be able to operate in an open back configuration. Can anyone think why that could not work?

[Jazzman53]

I don't know of any technical reason why an electrostatic speaker can't get down to 20Hz, except for the enormous area it would need to have any output at that frequency - but that's largely a function of the front-to-back cancellation of a dipole and the limited excursion potential. The former would be taken care of by a sealed box, but that's not unheard of - Janszen does it, although not at bass frequencies. I also seem to recall a French subwoofer that was electrostatic—or, at least planar—but I cannot find reference to it.
 
What I would like to see (or hear) would be an electrostatic sub in a configuration like a ripole but with multiple folds, like a Heil air motion transformer, but huge. It might move enough air to be able to operate in an open back configuration. Can anyone think why that could not work?

Technically and ESL with enough transformer iron iron can play to arbitrarily low frequencies but, as you pointed out, the panel area required to offset the limited excursion and dipole cancellation make playing down to 20Hz rather impractical.   

Also hindering bass from an ESL is its fundamental resonance (a.k.a drum-head resonance).   Just as a conventional woofer's response is basically useless below its FS, so too an ESL's response is impaired by its drum head resonance.  Owing to the diaphragm's ultra-low mass/inertia, an ESL is essentially a zero Q driver-- except at its drum head resonance(!) where its Q becomes quite high; resulting in a nasty-loud and muddied response at resonance. 

I suspect most ESL manufacturer's published response range (if even honest) actually expresses "resonance to XXKhz".  In fact, full range ESL's typically use the drum head resonance in a desperate attempt to make the speaker sound bassy.  Moreover, the diaphragm must be tensioned high enough to provide a restorative force to keep the diaphragm centered and not slapping the stators, so it becomes impractical to build an ESL with a diaphragm resonance lower than about 40Hz.

Soundlab employs a scheme they call "distributed resonance" to augment the bass over a wider band by sectioning the diaphragm to give multiple smaller resonances as opposed to a single large resonance.  Even so, a resonance is inherently uncontrolled and muddled motion-- so using it for bass output is a poor compromise in my view, no matter how you do it.           

While a hybrid ESL is challenged to achieve a seamless blend, it does offer the advantage of not having to vibrate the diaphragm near the drum head resonance.   

[Russell Dawkins]

I can think of one system where the bass driver/system resonance is made intentionally high so that the system is intended to operate entirely below that resonant frequency and the drive signal is EQ'd to compensate for the inevitable roll-off. That's the Bag End sub.

Perhaps the same scheme could be used with the deeply pleated Heil air motion transformer type I postulated. The drum-head resonance could naturally be above the operating range if the low-pass was set at something like 80Hz or lower, and the diaphragm could be stretched fairly tight to ensure that plus, in the process, keep the excursion under control. A lot of surface area could be squeezed into a Heil-type configuration if you imagine something, say, 15" deep and 18" high and 24" wide with narrow angles on the accordion-like pleats, enabling something like 12 pairs of diaphragms in a 24" width, allowing for 2" between each apex at the front (and rear, if it was a dipole).

Just musing.

[josh358]

Soundlab employs a scheme they call "distributed resonance" to augment the bass over a wider band by sectioning the diaphragm to give multiple smaller resonances as opposed to a single large resonance.  Even so, a resonance is inherently uncontrolled and muddled motion-- so using it for bass output is a poor compromise in my view, no matter how you do it.           

While a hybrid ESL is challenged to achieve a seamless blend, it does offer the advantage of not having to vibrate the diaphragm near the drum head resonance.

This is the scheme used by Jim Winey in the Maggies. Not only does it spread the resonances but it allows acoustic equalization to compensate for dipole bass cancellation. And done well, it sounds pretty good, in fact the Tympanis probably still have the best midbass of any speaker ever. Not all manufacturers do it well. There's some black art involved and also some integrity, since curves can be shaped to sell rather than sound good long term.

I suspect you could get better performance from a line source dipole woofer with good dynamic drivers, but the usual approach to hybrids is sonically marginal. Even if you do it right you'll probably be able to hear the transition because the distortion spectrum of a dynamic is substantially different from that of a stat and even with proper filtering you're going to get some distortion products where the stat would play clealy. Going with dipoles would help close the gap, since dipoles don't excite the X and Y room modes and so are *much* smoother in a typical listening room.

I think one of the main reasons the Tympanis are so good despite ringing from the acoustic equalization is that the ringing from room modes is much worse. Not to mention enclosure resonances and other problems like voice coil compression.

I've also long thought that mating a planar magnetic woofer with an ESL playing above its resonance would be a good thing. ESL's and planar magnetics have a similar sonic flavor but the resonances in a planar can be tuned lower and planars have 10X the output for a given surface area. Some people have done this themselves, mating ESL panels above resonance with planar woofers. An old pair of Tympani 1-D's would do the trick, with the bottom octave, if desired, supplied by a sub. Cost is low, but you need lots of room!

[josh358]

I can think of one system where the bass driver/system resonance is made intentionally high so that the system is intended to operate entirely below that resonant frequency and the drive signal is EQ'd to compensate for the inevitable roll-off. That's the Bag End sub.

Perhaps the same scheme could be used with the deeply pleated Heil air motion transformer type I postulated. The drum-head resonance could naturally be above the operating range if the low-pass was set at something like 80Hz or lower, and the diaphragm could be stretched fairly tight to ensure that plus, in the process, keep the excursion under control. A lot of surface area could be squeezed into a Heil-type configuration if you imagine something, say, 15" deep and 18" high and 24" wide with narrow angles on the accordion-like pleats, enabling something like 12 pairs of diaphragms in a 24" width, allowing for 2" between each apex at the front (and rear, if it was a dipole).

Just musing.

Remember that dipoles need 6 dB/octave equalization to compensate for backwave cancellation. So that's very demanding and planar woofers measured up close are actually putting out a tremendous amount of bass. Linkwitz uses critically damped drivers in his dipole woofers and does the equalization electronically. It is the ideal solution from a sonic perspective but it does limit output, you're going to be constrained by Xmax lower down and by amplifier power/thermal issues higher up in the woofer's range.

[josh358]

I find that claim suspect too.       

Me too and by chance I came across this comment of HP's when I did a search for the Innersound amplifier:

I wish we had more electrostatics on hand to assess the befores and afters of the InnerSound mating.  But we only have the Dutch Audiostatic panels, which we can't get the company to take back, and these are severely limited in terms of their excursive abilities, and even with the InnerSound, can't be played to anywhere near soul-satisfying loudness.

[josh358]

I don't know of any technical reason why an electrostatic speaker can't get down to 20Hz, except for the enormous area it would need to have any output at that frequency - but that's largely a function of the front-to-back cancellation of a dipole and the limited excursion potential. The former would be taken care of by a sealed box, but that's not unheard of - Janszen does it, although not at bass frequencies. I also seem to recall a French subwoofer that was electrostatic—or, at least planar—but I cannot find reference to it.
 
What I would like to see (or hear) would be an electrostatic sub in a configuration like a ripole but with multiple folds, like a Heil air motion transformer, but huge. It might move enough air to be able to operate in an open back configuration. Can anyone think why that could not work?

Doesn't the Quad use a folded woofer?

I don't think LF electrostatics do well in an enclosure, anything that's bouncing around inside will come popping out the front through the membrane. You could make a dipole box but you'd still be vexed by the drumhead resonance and it could also get very expensive, as well as being very big -- so H-frame dipole dynamic woofers or one of the other solutions start to look attractive.

[SteveFord]

It looks like we're up to seven grand now with delivery starting sometime in December.

The new Audiostatics will sell direct to the consumer starting at $6999 a pair
http://www.essenceelectrostatic.com/new-audiostatic-magnetostats-need-no-ac-power/