tube amps and electrostatics

"And although I can't formulate a meaningful technical explanation, and I suspect that a good explanation would be a complex one involving a multitude of factors, my perception over the years has been that there is a tendency for those qualities to often be compromised in systems that are designed and assembled in a manner that results in flat frequency response being a leading priority. "

I'll offer up this wonderful resource again here to help with that.

Audio Chart

Factor in the ear sensitivity curves to help account for why flat may be technically correct but not sound best.

Beside Roger Sander answer above in my last post which the non believers are conveniently blind to.
Here is and excerpt from the Stereo Times review of the difference when driving the Quad ELS2805 (while still hard to drive are easer than most ESL's) using tube then good solid state. Which also backs up everything Roger said in his White Paper and I've been saying and heard.

Stereo Times:
"The Quads are not as easy a load as one would be lead to believe by how good they sound with tube amplification. The Magtech further revealed the tube shortcomings (which I had already noticed) by expanding the peak performance range of the Quads. The “sweet region” grew to the limits of the speakers themselves. Meaning they suddenly didn’t have extended bass but what they did have was tighter and more refined. The top end was not more extended, just smoother and less brittle. The Magtech amplifier did not create new loudspeakers; it just let them be all that they could be."

Cheers George

As the ear sensitivity chart at the link I referenced above shows, human hearing is far from flat over the 20-20kz frequency range normally associated with human hearing.

That means nothing that truly measures as flat will ever be heard as being flat. Far from it, in fact.

So technically flat or superior does NOT necessarily mean better sound that we hear as a result of being flat at the source.

So you can hear things that are flat as something otherwise or you might hear something that is not flat as being flat, or any shade of grey in between.

Fun stuff! I guess the wide range of things that might end up sounding good depending mostly on personal preference is what keeps Walmart from taking over the high end audio business.

I think I will go out on a limb and argue that the desirability of flat response at the source is a function of the variability of the music listened to. If its flat at the source, then a random sample that represents all music possible will overall sound better as a whole. If its not flat, results will be more biased towards certain types or patterns of music.

That's consistent with how I understand things and what I actually observe in practice in that I listen to and enjoy all kinds of music equally, though I know I could tweak things to sound better with certain kinds only if I wanted to.

I do that to some extent by running multiple systems in multiple rooms, each of which sound different, but my main (my reference) system in my main room is the one that I strive to perfect technically in the interest of best sound overall.

Sounds like one could create a technical reference quality system using the right tube amp with a particular set of ES speakers, but perhaps it will be more of a challenge to achieve reference quality in practice, as opposed to merely sounding really good.

I used to own, the Acoustat 3 powered by a Conrad Johnson MV75A-1 -75 watt tube amp, no problems, beautiful sound.
I ran stacked Quad 57's with an AtmaSphere 30 watt stereo amp, beautiful sound ,no problems, also drove the same stacked pair with a 1961 Bell tube integrated(20 watts)great sound no problems.
Used to like my CLS 11Z speakers, but never found a tube amp that drove them as well as my mono Classe DR 6 amps.
Had a pair of Quad 63, that I never tried with a tube amp, but they did like the old Metner mono block power amps.
Now I am back to tubes and stats but it's the Acoustat X with it's own servo OTL tube amps.
Best combination so far of pairing a stat with tubes, but that should be as expected when each is made for the other.

Quad switched from tube amps to the current dumping solid state amps for any number of reasons.
Perhaps because tubes were felt to be obsolete, or because the newer 63 needed- demanded- more stability from an amp, or just because they wanted to, perhaps spurred on by the need to update their line.

I think,there are no rules set in stone,let common sense prevail and don't push either type of amp beyond it's limits.

I am over 50, and I know my ears like most older ears do not even hear much above 12khz or so like they used to when I was a young audio "stud".

So getting flat response that works becomes a lot easier with age. Roll off of highs with ES speakers may in fact be a non-issue for most of us old audio farts. WHose to say a lot of younger ears that listen to the same are sensitive enough for it to matter either.