Electrostatic Speakers & Amp

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Hi everyone,

After much reading of threads on the site I have to be realistic about how much time I can invest in a project. I was in a high end shop and listened to Martin Logan ESLs. I was totally blow away, but they are way above what I can afford.

Is anyone familar with the electrostatic speakers from Just Real Music. They offer a kit within my budget ($480) and the time I can afford to put it all together. Their web address is:

http://www.justrealmusic.com

The kit was offered on Ebay and is not listed on their site, but they'll sell it direct


Also what kind of amp would best drive these. Would something like a Carver M500-T be good. What other used amps should I look at. I'd like to keep the price under $300 if possible.

Thanks a lot for taking a look at this and your advise.

Best,
Ralph
 
While I don't see a kit there for $480, perhaps you are referring to each individual speaker's cost. But again, 480x2 = 960, which still doesn't meet the price of either of the speaker pair kits that I see on the Pricing page. Perhaps there is another deal not posted on his site?

I am by no means an ESL expert, but I have been reading up on it as I will eventually be venturing into making my own. I have read the ESL cookbook (not sure of author - at work right now) and numerous other texts, not to mention countless web-searches and forum readings.

The one thing I would make note of is his newer version with the rounded panels, the "Expanded Line Source" model. Flat ESL panels have the directivity of a laser pointer keychain. Experiments have been done with rounded panels, but I have yet to find any good documented information on these bent "arrays." From what I have experienced (Quad 57 and 63's of a personal friend's, and Martin Logan's in an in-store demo) the formed panels definetly have a wider "sweet spot." For serious listening the Quad's are wonderful. But managing the sweet spot in a busy family room could be an interesting feat. A dedicated room would be the best environement for the flat panels (and any system, obviously). Then again, getting the right kind of directivity from curved panels is a whole other story. Who know's what this guy's sound like (don't mean to pronounce extreme negativity - just stating the obvious).

The use of a Peerless 8" driver is mentioned, and that raises my level or respect for this Russ guy. There was some mention of comparing six different woofers for the new system - I'd be eager to see what others he was comparing to. But, in my experience with dynamic woofers, Peerless makes some outstanding units. Particularly the 8" DVC for the 8" group - wonderful driver, but it's hard to say exactly which one he's using by the pictures.

The Carver M500-T you mentioned is from what I know a fairly nice amp for ESL's, but it does have a certain "diffuse" and "airyness" to the sound, which many equate to the sound of tubes. This is a form of distortion, but if you prefer the sound (as many tube lovers do), go for it. Generally, I'm not a fan of this type of sound. The Adcom GFA-555 is a standard reference amp of decades past that is well-controlled with highly capacitive loads. I personally really like the amp, but upgrading the internal wiring can make a tremendous difference after picking up an old one off ebay. I have no intention of starting solid-state/tube debate, so other's please don't get offended - this is just my preference.

The other point of concern for me is what type of material/coating he uses on the diaphragms. I have come across the original Quad recipe somewhere, but I unfortunately don't have the link with me at work here. There are a multitude of reasons that this type of material is better than the normal DIY graphite technique, but many a graphite systems are better sounding than other types of diaphragm coating. There are so many variables with ESL's that one really has to experiment an awful lot to be able to appreciate the difference in diaphragm coatings.

In all my ESL research, I haven't come across this place yet... and that kind of bothers me. Perhaps I'm not quite as ready as I had thought to start my own ;) Nonetheless, it has indeed perked an interest. I may even consider getting a set from him just to experiment with. Nice find man :)

All things considered, it sounds like a very fair deal - and you'll get to learn a bit about ESL's by putting the kits together if nothing else. I'd say go for it... (but that's easy to say when it's not my pen in my checkbook ;).) Good luck - and let us know
 
Thanks for the input. In response to some of the points you made.

The kit is not listed on the site, but it was offered on Ebay and his response to my email indicated the kit is available for order.

I've read the ESL Design Cookbook by Sanders, and it's an incredible reference to building ESLs. However for most of my life my miter joints looked like butt joints put together by a blind person with numb hands. I have gotten better and am comfortable making the frames, but the precision necessary for the panels is beyond my skill. I also am interested in the curved panels.

My den is dedicated for music & home theater. The deal with my wife was; she got to do whatever she wanted in the rest of the house, and I got to do whatever I want in the den as long as I sound proofed it (which I did).

Presently I'm using two 10" Peerless subs driven by a Dynaco 400 and am very happy with the fullness of the bass. Eventually I want to build two TL enclosures firing into the den from the attic (effecient use of presently dead space). Planet10 gave me a very interesting idea for the enclosure.

In terms of the amp for ESLs; what I've read is that ESLs drop to 2 ohms at certain frequency and do need an amp with sufficent power and an ability to operate at low ohm loads without seld destructing. I'll read what I can about the Adcom, any other suggestions?

Thanks again.

Ralph
 
Re: Electrostatic Speakers & Amp

ralph-bway said:
Hi everyone,

After much reading of threads on the site I have to be realistic about how much time I can invest in a project. I was in a high end shop and listened to Martin Logan ESLs. I was totally blow away, but they are way above what I can afford.
You could look for used ones. I have ML SL3 and you can get those for 1500-2500 dollars in good shape.

I'm also thrilled by the electrostatic sound but they sounds like crap at exihibitions of some peculiar reason. The lastest was in Göteborg and the hotel Arken. The whole hotel has many good rooms when in comes to accustics but electrostatic speakers don't sound good there. At home my SL3 sounds splendid!
 
frugal-phile™
Joined 2001
Paid Member
ralph-bway said:
In terms of the amp for ESLs; what I've read is that ESLs drop to 2 ohms at certain frequency and do need an amp with sufficent power and an ability to operate at low ohm loads without seld destructing. I'll read what I can about the Adcom, any other suggestions?

Power isn't necessarily a good indicator. What is necessary is to be able to drive a heavily reactive load. I doubt the Carver would do the job. A Bryston probably would, but the NAIMs i used were better (even with les rated power).

Finding a cheap amp to adequately drive an ESL is a real challenge.

dave
 
As I recall, the freq where they drop to such low impedances is quite high. There will never be much energy at high freqs so that's not much concern methinks. I think the main challenge is th capacative load part. If you want to build a kit good for driving ESL's you can check out www.transcendentsound.com they sell a well designed OTL amplifer kit, which will do the job pretty well, but this is way over your 300 buck limit.

My 2 cents, keep us posted if you go for it. (The speaker kit I mean)

Chris
 
The impedance characteristics depend very much on the specific type of electrostatic loudspeaker. The famous Quad ESL-63's have an impedance of about 6 ohm over most of the audio band, with a minimum of about 4 ohm at 10kHz or so. No problem for any normal amplifier.
Flat panel ESL's are only terribly directive at high frequencies if the designer has been so foolish as to drive the entire membrane in phase for all frequencies. Using multiway techniques or concentric rings with a damped delay line, like Quad does, the directivity can be reduced as much as the designer desires.
 
diyAudio Senior Member
Joined 2002
Hi,

Power isn't necessarily a good indicator. What is necessary is to be able to drive a heavily reactive load.

A highly capacitve load is what ELSs reflect to the amp.
So much so that some sand amps baulk at it to the point that they spit out their protective fuses at a mere switch on.

As Christopher points out an OTL amp is close to the ideal for driving a xformer coupled ESL...

Another more complex route is doing away with the step up xformer alltogether.
Not that easy to achieve and the amp will be closely married to that speaker and little else.

:att'n: This always involves exposure to high, lethal, voltages for the DIYer,so you'd better know what you're up against.

Cheers, ;)
 
Nice

Well done Sheldon! Looks like you crossed all the t's and dotted all the i's. Nice. I'll go over the whole page when I've got time. I'm sure I could learn lot's!

I'm hoping to have a TL woofer mated to an ESL driven by my OTL's someday in the future. Likely, I'll go for high power SS for the woofer.

How's that for acronymity?

Chris
 
Just a quick theory question.... if the "ideal" speaker is a vibrating sphere, and the "ideal" line array is a vibrating cylander from floor to ceiling, why not do an ESL that is completely bent into a cylander? How complicated could this be? and....would it ruin the response? or solve all the ills of the world? I'm not an expert...just curious :)

-Matthew K. Olson
 
Matthew, it's not clear that the "ideal" speaker is a point source or a line source or something else. Those just happen to be easy cases to solve the equations. We tend to be like the drunk who's looking for his keys under the streetlight even though he dropped them in a dark spot 50 feet away; it's just that it's easier to see in the light.

In any event, cylindrical ESLs have a fundamental problem stemming from the acoustic transparency of the membrane. Think of the part facing you directly as zero degrees. Now the element exactly 180 degrees away is radiating away from you in phase with what the zero degree element is radiating toward you. But... the backwave of the 180 degree element is also radiating toward you and will set up a comb filtered response for the direct wave because of its distance from the zero degree element. You could put some sort of perfect absorber inside the cylinder; when you find one of those, let me know.
 
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