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Between the 2, which one you guys prefer the most on electrostatic loudspeakers?
If you are wondering what speakers to use, then you might consider buying a pair of Sound Labs, any of their full-range ESLs that use two audio step-up transformers, one for bass and one for treble, from the M1/A1 on up. Then remove the components of the passive crossover that divides the frequencies between bass and treble, particularly the RC network. Then substitute the toroidal treble transformer with either a toroidal or EI type full-range ESL step up with a 1:75 or 1:90 step-up ratio. Best quality you can find. This will do two wonderful things for an OTL amplifier: (1) The impedance of the speaker goes up to around 20-25 ohms across the spectrum, only falling off at the high end, and (2) Efficiency is markedly improved, over and above what one might expect just due to the impedance lift, because now you've removed that R in the RC network which was wasting amplifier energy. You can leave the inductor that rolls off the bass transformer in place, or not. It doesn't make much difference because the SL bass transformer rolls itself off anyway, above 1 kHz.
After I had done these mods to my SL 845PXs and during my first listening session, there were literally tears in my eyes; finally I had gotten the best out of the SL speaker. Three years or so later, I am still very very happy.
As to Quad 57s, you might consult Dave Slagle (Intact Audio) on how to get the most out of them, especially if you want to use 3 pair. It's been done by a guy here in the Maryland area under Dave's guidance, and he is very happy too.
That's a pretty good question- I'd be curious to know as well!
My bet would be on the Alan Kimmel amp. Both are competent designs but I am probably biased (imagine that) and prefer the symmetry of the Circlotron. Alan's amp is quite competent! But finding one might be a bit of a trick; as far as I know he only made a few for himself and friends. There are DIY articles on it though.
I'm fans of circlotron but I know the Transcendent Sound has great potential. However, I heard most circlotron OTL are work extremely good on most electrostatic and the Transcendent Sound is very picky to electrostatic from different manufacturers, I guess mainly due to impedance curve......
Which one do you have in mind?
Martin-Logans are very low impedance as ML wants them to work with transistors. If these are planned you will need a set of ZEROs.
Sound Labs work nicely with OTLs but need some power. In most cases unless you have older SLs the amps should make at least 100-140 watts and more is better.
Quad ESL 57s don't need much power and so smaller OTLs can work. ESL63s work OK with 60 watt OTLs but work with more power; 100-150 watts works very well with them.
There are some pretty profound differences here so its important to understand how they will work together!
One thing I forgot to response to this post, the The Ultimate-1PXF should work well with both premium 100W to 150W solid state amp and high power OTL.
I guess the solid state amp capable much lower output impedance, so output power might not a factor to concern, anything around 100W is fine. A fellow friend has Mark Levinson #20.6 sounds great on his Sound Lab.
ESLs can be quite tricky for solid state!
The reason is they have a high impedance at low frequencies and a low impedance at high frequencies.
Solid state already tends to sound bright; when you combine that with the inability to make power in the bass region, the result is a system that is bright and the amp not making anywhere near the power it should be (and likely not enough bass impact).
This is why a 140 watt OTL can keep up with a 600 watt solid state amp on Sound Labs, and actually play better bass.
Besides the pure impedance issue, I believe that the capacitative nature of the load presented by any ESL poses issues for some solid state designs, particularly those that use a lot of NFB. Many of the older designs become unstable trying to drive what is essentially a giant capacitor. Modern SS amplifiers may be less prone to this type of problem, depending upon the topology and the amount of NFB.
But I don't see the problem for stacked ESL 57 and wired in parallel with solid state amp.
ESL57s in parallel will work with a solid state amp, but with similar results.
The reason is that on most ESLs, the impedance curve varies by about 9-1 or 10-1 from the bass region to the highs.
So a Sound Lab is about 30 ohms in the bass and about 3 ohms at 20KHz.
A Quad ESL57 is about 45 ohms in the bass and about 4 ohms at 20KHz. This makes it tricky for any solid state amp to make bass on the speaker. As a result, what usually happens is that the speaker winds up being a bit too close to the wall behind it as the owner tried to reposition the speaker to get bass. In a way they will have succeeded- but the speaker will have a sort of 'one note' bass as what is really happening is the backwave is reinforcing at one frequency only.
If you put the speakers in parallel you still get that 10-1 thing.
I used to own ESL 63 and love to put solid state amp on it, especially Metaxas Soliloquy.
After listening to the ESL 57 stacking (wired 2 in series), and the result is mind boggling driven by 50-60W tube amplifier (not OTL). Example: Marantz 9 in triode, Quicksilver 8417...
I heard people complaint the Grant Lumley amplifier has weak bottom but it sounds really good on Quad ESL 57 stacked and wired in series.
Rumor has it that OTL work s even better on ESL 57 wired in series. So that's why draw my attention and now I have 2 x ESL 57 wired in series.
Actually Martin Logan sounds pretty good with Conrad Johnson amplifier, just magic!! But not others, especially solid state. Very hard to mate solid state with ML ESL
-are easy to drive and 60 watts is plenty of OTL power for them. We've got customers that have run that for years. IMO any 60-watt OTL should do the job for that.
I'm repeating myself here, but will chime in to agree with Ralph. My Stax F83's have a very high impedance in the midrange (over 100 ohms), but falling impedance in both the bass and treble (around 4 ohms). They are also very very inefficient, rated at something like 76db/watt, and have the reputation as amplifier killers. But with an subwoofers to take care of the bass, an 80 watt OTL amplifiers drives them beautifully, with astonishing transients and very convincing dynamics.
Friend of mine has mentioned the possibiluty to stack 3 × ESL 57 and had them wired in series as well. Don't you think 60w still enough under this circumstance?
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