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[Johnboy Walton]

Harvey,

I apologize for the somewhat off-topic post, but I've been lurking at PSW and RecPit for some time devouring all of your in-depth tech articles on microphones and speakers.  

Last night I ran into a pair of electrostatic speakers at a hi-fi shop, and thought they sounded kinda mushy.  Since you did such a killer job describing all of tradeoffs in conventional (and some un-conventional) speaker designs, I was wondering if you could give me a quick explanation on how electrostatics work (giant capacitor?), and what tradeoffs have to be made to get a functional acoustic tranducer.  

Anyway, if you can see fit to answer this question, I'd be most appreciative.  I would reason that, with your hands-on design experience, you would have a more honest take on they're operation than anything I'd find within the hi-fi community.

Johnboy

[hargerst]

As you guessed, it's just a big capacitor, and because the membrane is very light, the mids and high end can sound amazing. Where they fall down is in the low end because they don't couple well to the air at the very bottom.

Because they're a distributed source (as opposed to a point source), they take a bit of getting use to.  They don't have an in-your-face, aggresive sound, and you don't realize just how smooth they are at first.

All in all, they're lovely sounding for lower listening levels.  I wouldn't try to do a heavy rock mix on them.

[Johnboy Walton]

Harvey,

Thank you very much.  That explains pretty much everything I heard.  They were set up in a "home theater" room, with a theatrical trailer running (action flick). They sounded great during the quieter bits, but there were some occiasonal loud parts that seemed pinched-off.  They certainly did a very nice job of filling the room with the highs/mids, and there was definitely no beaming at all, but I guess that's what threw me.  

Thank you again for the information.  Your generosity with help in today's musical and internet evironment will ensure that you'll always be welcomed with open arms anywhere you care to go.

Sincerely,

Mike Davis
(part-time audio nut)

[Marik]

Thanks Harvey,

In a few sentences you have covered pretty much everything. I would add a couple things. Quad ESL63 is probably one of the exceptions--it uses specially designed concentric arrangement, so the speakers work pretty much as a point source. Needless to say, the image is superb. However, Quad electrostatics have a big con--they use Mylar dust covers, which change the sound quite a bit. I serviced a lot of ESL57s and can tell that without these dust covers (and grills) they sound muuuuch better.
Electrostatics work their best when coupled with conventional woofers with crossover point at about 300-500Hz, because of severe LF cancelations. Martin Logans CLS-II 'full range' used two coupling transformers, one of which served as an EQ boost for LF to compensate for the cancelation. Anyway, they are big and extremely inefficient. Since they are 'open baffle' design, positioning in the room is critical.

Once I made a direct coupled, based on 845 big transmitting tubes amplifiers to drive my Martin Logan electrostatics directly (without any transformers). They sounded wonderful, but after I met my fiancee they had to go...

[malice]

Marik wrote on Thu, 06 May 2004 21:37

Thanks Harvey, In a few sentences you have covered pretty much everything. I would add a couple things. Quad ESL63 is probably one of the exceptions--it uses specially designed concentric arrangement, so the speakers work pretty much as a point source. Needless to say, the image is superb. However, Quad electrostatics have a big con--they use Mylar dust covers, which change the sound quite a bit. I serviced a lot of ESL57s and can tell that without these dust covers (and grills) they sound muuuuch better. Electrostatics work their best when coupled with conventional woofers with crossover point at about 300-500Hz, because of severe LF cancelations. Martin Logans CLS-II 'full range' used two coupling transformers, one of which served as an EQ boost for LF to compensate for the cancelation. Anyway, they are big and extremely inefficient. Since they are 'open baffle' design, positioning in the room is critical. Once I made a direct coupled, based on 845 big transmitting tubes amplifiers to drive my Martin Logan electrostatics directly (without any transformers). They sounded wonderful, but after I met my fiancee they had to go...

Mark,

I already was very interested by your post about ribbons at Klaus forum.

I had the chance to try some Quad system coupled with traditional woofer.

For some music that require acurate stereo imaging and detail in the upper mid range it was simply among the best system I ever came across...

chamber music on that kind of system is simply amazing

well, enough of audiophile OT

best

malice

[LanceSexington]

I live about 10 miles from the factory that Martin Logans are made. in Lawrence Kansas...I my opinion a modification is needed to make the woofer operate in the region above 700 cycles to about 2500hz I have Liniam speakers on my theatre system and they have more balls because the crossover is in the right place...when glass breaks It sounds real and the pattern is 360 so the sound doesnt beam at you but the sound happens in the location on the soundstage...its different.

[Breck]

      I've got a pair of Acoustat 2+2's- I got them from a fellow I used to work with because they were too tall to fit into his new apartment. They're 8' tall, 2' wide, and about 5" thick. Not a good size for preserving marital harmony.

     I used them as my main speakers for awhile, and I agree with everything that's been said so far. They definately do not rock. A sub can help.

     I don't find the imaging to be particularly amazing on these. They seem to have an overinflated soundstage- They don't 'hang a voice right there in the air in front of you' like some other speakers do. (Notably, some Dynadio Contour speakers I've listened to- holy cow!) Instead, they sort of smear everything around, a little like a Bose 901    direct/reflecting system does. This probably has something to do with the fact that most membrane speakers are bipolar- they radiate sound from front and back, like a bidirectional mike in reverse.

     The Acoustats have found a very happy home as the rears in my home theater setup. And people always say "Wow! What're those"!?

[fishtop]

Johnboy Walton wrote on Tue, 04 May 2004 14:39

Harvey, Last night I ran into a pair of electrostatic speakers at a hi-fi shop, and thought they sounded kinda mushy.

As others have noted, electrostatics don't do low frequencies
well. And if you add a subwoofer, there can be noticable
switching.

Two other important notes on electrostatics, well three...

1) they can sound wonderfully open and realistic for orchestral
work, better than any normal speaker IMHO

2) they are dipolar, and have to be away from the wall.
And the wall and reflections are critical to the sound.
So proper placement is critical to make them sound right.

3) they present a weird load to the amp.
Strange complex impedences that take a lot out of the
amp. A wimpy amp will not do at all.

But if I had the room to have them, I'd get a set of maggies or
Quads.

[Marik]

fishtop wrote on Mon, 17 May 2004 04:21

Johnboy Walton wrote on Tue, 04 May 2004 14:39 Harvey, Last night I ran into a pair of electrostatic speakers at a hi-fi shop, and thought they sounded kinda mushy.   But if I had the room to have them, I'd get a set of maggies or Quads.

Fishtop,

Maggies are planars, and their principle is very different from electrostatics, as they use magnetic field. Also, unlike capacitive load of electrostatics, they introduce purely resistive one, as seen by amplifier.

[Dave Martin]

I should point out (not to argue, but for comparison and informational purposes) that my Leslie 21H uses an electrostatic woofer. I don't notice a lack low frequencies when the organist is kicking pedals.

[Greg Youngman]

Dave Martin wrote on Mon, 17 May 2004 06:13

I should point out (not to argue, but for comparison and informational purposes) that my Leslie 21H uses an electrostatic woofer. I don't notice a lack low frequencies when the organist is kicking pedals.

I'm not familiar with the 21H Leslie, but don't the older Leslies typically have "electromagnetic dynamic speakers" and not "electro-static"?  

[fishtop]

Marik wrote on Mon, 17 May 2004 04:42

fishtop wrote on Mon, 17 May 2004 04:21 But if I had the room to have them, I'd get a set of maggies or Quads. Fishtop, Maggies are planars, and their principle is very different from electrostatics, as they use magnetic field.

Opps, sorry, my bad.
If I remember correctly this time, maggies have really
thin electrical conductors in the panel, with all sorts of
voodoo to make it phase coherient.

Still, whatever the technology, Quads and Maggies sound
wonderful. Just too big for my decorating commitee.