XXHighEnd

Finally, John Atkinson has reviewed my speakers for Stereophile. He's actually reviewed the Quad 2805 speakers, which I have playing behind me right now in my home office/study. I also have the larger 2905 speakers in my main listening room.

And I have to say that I concure with everything that he's written. Bang on the money.

Find some time to take a look at his measurements of these speakers. There is nothing amazing about their frequency performance, although they pretty much match a pair of $36K Sonus Faber Amati Futura speakers. BUT take a look at their temporal performance. I really don't think there are another pair of speakers on the planet that could match figs 7 and 8. Oh and their THD performance is very, very good too (fig 10):

http://www.stereophile.com/content/quad-reference-esl-2805-loudspeaker-measurements

Certainly not the best speakers for heavy bass lines (the 2905s are much, much better for this). But otherwise amazing music producers.

Mani.

Thanks for the link to the review Mani.  It sounds like the new Quad 2805's are a nice looking repackage of the classic (now) ESL63.  I have't heard the new ones yet, but hopefully one of these days :-)

I love these speakers, so I'm going to talk them up a bit!

It makes me sad to think Peter Walker is gone.  What a genius and a genuine nice guy.  I remember calling Quad on a couple occasions and having him answer the tech support call.  I wish I had understood enough back then to ask some intelligent questions! 

I'm on my third pair of Quad ESL63 based loudspeakers.  The first pair I purchased new were the original ESL63 with the aluminum louvers.  That pair I modified quite a bit and they were the best sounding (after mods).  I foolishly sold them thinking I could get my Altec/Jensen/W.E. horn speakers to that high level of midrange realism.  I was attracted by the amazing dynamics and easy amplifier choices of the big horn system.

Unfortunately, I could never get horns to cross over well enough to beat the Quads in the midrange.  I tried biamping horns with active crossovers.  I designed passive LCR networks for biamping and even a built delay derived linear phase network.  It was much much better, but they never quite had that believable midrange of the crossoverless Quads.   Finally years later, I'm back with the ESL63's again and dealing with the limitations.

I think the Quads are a great speaker if you are willing to spend some time getting the most compatible amplifiers.  I've used a lot of different designs both solid state and (mostly) tube.  Well regulated Class AB or Class A seems to be the key as long as the feedback phase stays proper under the electrostatic load. 

I read Mani's Sauermann amplifier review with interest, but I couldn't tell how the feedback works exactly.  I'm curious if the lowest frequency time constant is at the output stage.  That seems to be the key for hard capacitive loads.

The most interesting amps I've used so far are a pair of 5000 volt Acoustat servo amps that I modded with a different front end.  They are a balance bridge like the Sauermann with a 5000 volt power supply!  I connected the high voltage output directly to the Quad delay lines via high voltage wire which bypassed the Quad input transformer entirely.  One great thing about the ESL63 for direct drive is that you don't need to EQ since all dipole EQ is done by adding extra bass radiator area rather than boosting bass signal like most other electrostats.  I'm afraid to use these (possibly lethal) amps now because I have a young child in the house, but they were great fun.

For Quad users who miss high output, the right subs and crossover can make a big difference.  Once you remove the bass excursions, the Quads are much more competent for rock music or big symphonic stuff.   Right now I have the old Gradient SW63 system designed for the ESL63.  The subs sit under the speakers by design.  It's not the best thing probably and the stock crossover (mod or replace) is fairly awful, but it's a dipole subwoofer and that keeps the radiation pattern nicely matching the ESL63.

With the subs, the ESL63 goes from being a speaker that makes me slightly nervous when playing loud, to one I don't think twice about.

I insist that my "audiophile speakers" sound normal when I'm in the next room and Quads seem to do that very well.  Unlike a lot of other speakers, the response seems balanced wherever you are in the house.  No doubt, this is due to the extremely uniform radiation pattern. 

Perhaps the best thing about the Quads IMHO is what they do when given the best signal quality.  As you improve other components, they seem to grow in stature.  If you get a pair, don't sell them!!  Sell the other stuff :-)

Greg

One of THE measures to find out whether things are quite all right or completey wrong IMO.
All indeed should remain balanced sounding. I always explicitly watch for that when being at in toilet or when I'm outside and the sound has to travel around a couple of corners.

Peter

Hi Greg, wow what a write-up! Thanks for sharing.


Bloody hell. I heard of some people putting OTLs inside ELS57s and bypassing their input step-up transformer (I think TdP did, but I may be wrong) with amazing results apparently. But I totally understand why anything like this is simply not a good idea with young kids (crazy audiophile adults?) around.


I thought long and hard about doing this when I had a pair of Pass Labs XVR1 crossovers hanging around. But I decided to go for the larger 2905s (with extra electrostatic bass panels) instead. I don't know, I didn't want to ruin that beautiful step response I suppose and no matter how good the sub, it just ain't gonna keep up with the Quads.


I'll try not to...

Cheers, Mani.

Yep, actually a few companies tried this.  Beveridge is another and there were articles in Audio Amateur for do it yourself amps.  Quite a long time ago, I contacted EAR to ask about the ones you mention for the ESL57 mod and they no longer did them.  I wasn't clear if just the tweeters were connected to the tube anodes or if all panels were driven directly.  There would have to be a rather difficult network so it was probably just the tweeters. 



You might be surprised how well a dipole sub with a matching radiation pattern mates with a Quad.  I'd say it will play at least 6db louder, but Gradient used to advertise 10db and of course much deeper than a ESL63.  I've read that the larger Quads play deeper, but not much louder because the full range section is still getting the full spectrum voltage signal.   Curious if that is true.

Greg