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[Kevin Wood]

....I don't actually know if they work. Do they have thin membranes or some issue? Polythene?

Instead of having cones that are driven in and out by an electromagnet, as in a conventional speaker, they have very light plastic membranes which are alternately attracted to and repelled from conductive meshes by a high voltage signal derived from the amplifier output.

This eliminates a lot of the distortions caused by conventional speakers, and adds a few quirks of its' own. But, the membranes can become damaged by the high driving voltage flashing over, or can be contaminated with dust.

They also need a mains supply because a high voltage "bias" voltage needs to be applied to charge the membranes before they will behave in the way described.

[chrisgixer]

Yes sounds familiar actually. Think Dad had his referbished due to some issues.

The owner of these had the Beosound 9000 as his main unit. Not sure where these where positioned in the room. They may have been surplus to requirements and he just refused to let them go. I'll ask the family if the kettle leads are around.

Of course, your more than welcome to come and play. Do they require a certain amp type or is it just a quality / safety concern...?

[chrisgixer]

Suspect they could do with the grills off and a clean. They have that aroma of dry dust about them. Or is that just the wooden innards?

[Bigron]

UNLESS you have a Quad amplifier (303 or 405), limit the amplifier power to about 10 watts - they don't require much power to drive them anyway as they are voltage-driven. Too high a drive voltage and you can get flash-over inside the speakers, maybe killing both speakers and amplifier.
Yes, they are difficult to drive, position and even live with, but in the right location and circumstances they are wonderful!
But all the above difficulties ware why I opted for my Tannoy Yorks, large bass reflex cabinets with 15 inch dual-concentric motor units with a very solid and precise sound image - ALMOST as good as the Quads.......

Ron.

[chrisgixer]

Did I mention that I have a quad 405? 

Woo. Tell me more...

Designed for the quads?

[Kevin Wood]

Yes.. ish.

The issue with amps is that the impedance of the electrostatic speakers drops at high frequencies, which is the opposite of the behaviour of most conventional speakers, so some amplifiers struggle to drive them even though they require only modest power.
Another issue is that they have a draconian protection circuit which crowbars the output of the amplifier if the air around the panel starts the ionise, the precursor to a flashover. This requires good current limiting in the amplifier or it can go pop.

And yes, they can be damaged by too much power quite easily, and modern amps are much more powerful than what was around when they came out. (as is the Quad 405, but there was a way of limiting its' output)

[Kevin Wood]

This is how to do it, by the way:

[chrisgixer]

Quad quads

Seen some mounted over and under in a rack. Bit 60's looking but imagine the sound.

[chrisgixer]

55's presumably?

[Kevin Wood]

57's IIRC, with some software to generate 4 channels from 2 by adding delays and mixing a little. Makes that sweet spot a bit larger.

[chrisgixer]

Interesting to hear how they compare to more modern stuff. In the same room with the same source. My home cinema speakers aren't anything special but Dads always fairly impressed with the sound. Generally he keeps commenting on how good modern speakers are but I wondered, after a certain point, if it was the source that was key. He was very much a vinyl man. Until CD/DVD arrived.


...and by arrived I mean in his life, not "on the market"

[Marks DTM Calib]

Good modern speakers are.....very good.

The old electrostatic speakers setups I always found worked best on a valve amp and vinyl source mainly due to the rich (read even harmonic distortion) of the amp and the fact that vinyl was always very much more crisp in the top end. The problem with the valve amps was always the crowbar protection tended to goose the output stages if it kicked in however, they do tend to handle the odd impedance characteristics better and output power is usually fairly low.

This makes them a bit of a niche but gives some variation to the modern over precise sounds we are used to with CD and Mosfet amps.

[Kevin Wood]

Sources and amplification have pretty much "been done" these days IMHO, unless you're talking about vinyl, where the source is electromechanical, so you have some interaction between turntable and its' suspension, the tone arm and the cartridge to play with.  You can spend and spend on the latter and get little improvements. Depends where you want to stop!

Get a few competent digital sources together and you'll struggle to hear much between them. The same is true of amplification. I went to a hi-fi gathering a few weeks ago where we must have listened to half a dozen amps, both valve and solid state. Really, the only thing you could glean was slightly looser bass on some of the valve amps. Oh, and smoke coming out of one of the older solid state ones! Still sounded good, mind.

I've heard quads with both valve and solid state amplification and I think they actually work well with either. The great thing about them is that there's very little colouration in the midrange, where a conventional speaker has to  have a cross over somewhere in this region, and the effects can be difficult to hide, because that's where our hearing is the most sensitive. Quads don't do the extremes of bass or treble that well, so can sound a bit "old fashioned". You can always add a tweeter to extend the HF response and the aforementioned sub, of course.

They are kinder to valve amplification because they don't need a lot of damping, something that can cause valve amps to sound a bit muddy in the bass. I've never heard valve amps deliver bass as "fast" as with ESL57s.

The most important factor is how the speaker and room interact, though, especially for dipole designs like the ESL. Put the best speaker you can buy in a room that doesn't suit it and it won't sound great.

[Bigron]

Mark, I always like your well-presented and reasoned input, so I'm not sure if I'm disagreeing with you here or not.....
"The old electrostatic speakers setups I always found worked best on a valve amp and vinyl source mainly due to the rich (read even harmonic distortion) of the amp"
...but my understanding is that even harmonics are cancellelled in the push-pull output transformer of a valve amplifier, leaving only the fundamental (of course!) and the nicer-sounding odd harmonics which do not spoil the enjoyment like the harsher even harmonics. Psycho-aural experts will be able to explain why: I can't!

Ron.

[Kevin Wood]

My view:

The distortion signature of a push pull valve amplifier with negative feedback isn't that different to a solid state amplifier IME, although there will inevitably be more distortion there, assuming both are competent designs.

But.. many valve aficionados will argue that going push pull negates all the "benefits" of a valve amp and that you should use a single ended triode without feedback. Then you have even order distortion in spades!