Solid State Amps for Quad ESL 57?

My system is feeling pretty tube-y and I was looking for suggestions of a solid state amps that people are liking with their original Quad ESLs. Looking for more speed and more of the bass I know the Quads can put out if set up right.
Bass is hard to get with transistors and Quads. The problem is that the speaker does not run according to the rules that a lot of box speakers use- it seems to work best with amplifiers that can make constant power regardless of load- which is usually a tube amp.

Many transistor amps will double power as you cut the load impedance in half. The Quad has high impedances in the bass and low impedances in the treble/HF region. Most transistor amps will play the speaker with weak bass and too much highs.
Given Atmasphere's explanation, maybe this is why some find that the old Quad 303 works reasonably well with Quads. It is solid state, but my understanding is that its power output actually drops as impedance drops. There are a few firms that do updates, like Net Audio or the new one that advertises on EBAY.
Back in the day, the SS amps that paired well with the Quads were the Levinson ML-2, the Bedini 25/25, the Pioneer M-22, and the Classe DR-2.
Quad 909
The transistor amps will not give you what you want , in my opinion. I have been a confirmed user of transistors since I built a Heathkit in 1963 and was a Quad dealer for 15 years. Transistors are undoubtedly faster on cone speakers , because of higher dampening factor among other considerations. But these factors do not apply to the Quad, which is already faster than any cone. When I was a dealer I drove my 63s with Krell, Musical Fidelity and Stax class A solid state amps but could not detect a difference in speed or bass between them and good tubes. A friend drives his 57s, which I sold him in 1975, with a rebuilt Heath tube amp , it sounds as good as anything I have ever heard drive them. Foster Blair rebuilds them, they are available through Mapleshade. This is one case where having a transformer in the line helps the sound. After all, they were designed with a lower powered tube amp in mind. If I wasn't happy with the sound of the 57s driven by a good tube I would look at another speaker, they are what they are and the amp will not change them that much.
A friend of mine runs them with parasound and loves the match. He switched from big EAR tubes without sacrificing any quality.
It does sound like maybe I'm barking up the wrong tree. Maybe it's a front end issue. I have heard the JC1's sound great with Quads but they are out of my price range unfortunately....

Hello Dhcod,

That's interesting!
I have two Parasound Halo JC1s but never thought these are good amps also for the Quads ESL
Do you think they are good on the Quad ESL63 too?
The Quads will only take a limited amount of power and can be damaged by over driving. I never had any trouble as I was careful with the volume but one of my customers bought 63s and a Musical Fidelity 270 [100 Watts?] and had to have them repaired 3 times because he constantly over drove them. A big amp is fine used with care.
Never used them with the speakers, but based on Atma-sphere's comments, it is possible that the older Pass Aleph amps might work in terms of the impedance issues mentioned - they are of course very good sounding SS amps, but the matching issue may be handled by the Aleph's output into changing loads, if I rememebr correctly, they worked much like tubes in that sense.
If you really want to use a ss amp. The JC-1s little brother the A21 is much cheaper and sounds excellent on my Innersound Kayas.
Sarcher30, Innersounds are built with lower impedances in an effort to make the speaker more compatible with transistors. The Quad ESL 57 has a peak of more than 50 ohms in the bass; there simply are not a lot of transistor amplifiers that can drive a load like that with any power.

To give you an example, let's try a 200 watt SS amp, which does 400 watts into 4 ohms. Into the Quad, it will be limited to about 30 watts in the bass. OTOH, it will be able to make 500 watts at high frequencies! Its easy to see why people perceive such amplifiers as very bright and no bass when used on the ESL 57.
Atmasphere, Thanks for setting me straight. I have no experience with quads and Atmasphere's knowledge is much more complete than mine. So it looks like a tube amp is the best course.

I read somewhere that for instance if 100 wpc into 4 ohms produces 100db spl then 100 wpc into 8 ohms should produce 103 db. I think it was a car stereo book. It seemed to say that every time you half the impedance you loose 3 db of output. This seems to contradict what you are saying. Does what they are saying only apply to the voltage paradigm and not the current paradigm. I've read many of your posts about this and I still don't quite understand it all.

Hi Sean, Whatever that was that you read is misleading- it violates Kirchoff's Law, the law of electrical energy conservation. IOW if you put 100 watts into 4 ohms or 100 watts into 8, the output will be the same if the speaker efficiency is the same.
Hi Ralph, So can efficiency change with frequency? And if it can't how can a transistor amp sound right on a speaker without a flat impedance curve?
I found this exerpt from The Complete Guild To High End Audio. "Some amplifiers barely increase their output power when driving 4 ohms; others can double it. This means that not all 100wpc amps are created equal. One 100wpc amplifier might put out 150w into 2 ohms, while another might deliver 350wpc into 2 ohms. This ability to drive low-impedance loads (specifically, to deliver lots of current) has a large influence on an amplifier's sound and subjective power capability.
This is where our dBW rating again comes into play. When calulating dBW, subtract 3dBW from the 8 ohm dBW rating when the amp is driving 4 ohms, and subtract 6dBW when the amp is driving 2 ohms. In the example of of the two 100wpc amplifiers in the preceding paragraph, each is rated at 100wpc into 8 ohms, or 20dBW. But the first amplifier puts out only 150wpc into 2 ohms, while the second puts out 350wpc into 2 ohms. Converting the 2 ohm power ratings into dBW, we see that the first has a dBW rating of 15.76 at 2ohms, while the second has a dBW rating of 19.44dBW into 2 ohms. Quite a difference-nearly 4dB-between two 100wpc amplifiers."

He doesn't explain why you have to subtract 3dBW when driving 4 ohms as opposed to 8 ohms but I have read this elsewhere also.

Maybe some transitor amps run out of voltage when trying to drive a high impedance load and thats why there is a tonal imbalance? Or am I wrong about this?
My LP12 was outta wack. I had an overhaul and setup done and now things have gone back to the way they were. Thanks to everyone for all the info. I'm going to try out a Bedini and maybe the Red Wine Audio amps for fun!
Hi Sarcher30, in the case of transistor amps, the ideal is to be able to deliver the same output voltage regardless of the load impedance. That being the case, then a 100 watt amplifier driving 8 ohms will make 200 watts into 4 ohms and 400 watts into 2 ohms until the current limits of the power supply or output section are reached.

They thing they don't tell you is what happens when driving higher impedances, like you see in the Quad ESL 57. Into 16 ohms you get 50 watts, into 32 ohms you get 25 and the ESL 57 has impedances in the bass well in excess of 45 ohms. So transistor amplifiers cannot make power in the bass, while at the same time they make too much in the highs, where the impedance of the speaker is down to 4 ohms.

This is what I was trying to explain earlier. The Quad's impedance curve has nothing to do with box resonance in fact it has nothing to do with resonance at all. So it does not use the rules where the constant voltage characteristic is useful. It expects constant power out of the amplifier, or at least the attempt at it, for best results. It is what I call a Power Paradigm device, which is why transistors for the most part are tricky at best to get even mediocre results. IOW its an equipment mismatch. see
Robin Wyatt and David Chesky run theirs with an ASR Emitter I
hi ralph:

i own a pair of pk quad 57. you can get bass extension with a solid state amp. wayne has used several. in my own experience, beefy power supply and more power=greater extension and fullness.

personally, i wouldn't use a ss amp on the quads. i do not like the upper mids, lower treble, where ss amps are notoriously , unbalanced, i.e., somewhat peaky.

the problem with ss amps is not bass response, it is at 1000 hz and higher. I experienced this on my magnepan as well. i got reat bass with a 350 watt class a, but female voices and violins were a big problem.
I just noticed one that should do a good job if you want to use solid state, the Audiophile Boutique is closing out the Van den Hul Array 1 for under $1700 US, about 40% of original cost. They are very overbuilt for their output and should be able to drive Quads, I would check with them to make sure. If you are not familiar with Van den Huls work look him up, he knows what he is doing. My first post was not intended to say you could not use transistors on Quads, obviously I did. I just did not experience a greatly increased bass. I use transistors for the same reason Mr. T uses tubes, better vocals and top end. Many like the euphonic coloration tubes add, I prefer accuracy. On the power question, a transistor amp SHOULD double its power when you halve the impedance. Those that do are called voltage source amps, the ones that level off or decline are current source amps. The voltage amps require much bigger supplies and heat sinks etc. and are usually much more expensive. The output of a speaker is governed by the efficiency of the speaker as well as the output of the amp. The efficiency is given in terms of what its output in dbs are for one watt input. Doubling the amps power output will raise the output of the speaker 3db. So a speaker of 89db efficiency will require 1/8 the power of an 80db speaker if my math is on. [ 1 watt times 2 =2 watts, times 2 =4 watts, times 2=8 watts. ] You can see how very efficient speakers require little power.
Dchod,careful with Red Wine,if you're going that route you may want to consider the 70.2 mono blocks.I auditioned the 30.2 with my Innersound stats and it didn't float the boat.It was simply a clipping issue which I'm sure would not be a problem with the 70.2's.
Hi Ralph, So the box resonance is what makes the voltage paradigm work. Without the box the current paradigm is the way to go. So I assume open baffle designs and horn designs would need the current paradigm also if their impedance curve is not flat. That makes sense and would explain why alot of people perfer tube amps for these type of speakers. Thanks for taking the time to explain.
Try a Quad 303, updated and modded by one of the pros.
Mrtennis, the only way I've seen proper bass out of Quads with transistors was when the panel was too close to the rear wall.
At the same time the highs were dreadful- harsh and lacking real speed. I have trouble believing something like that could be termed 'accurate'.
I use a rebuilt and updated 405. The only mod i did was replace the TLO71 with an opa227p (not just a drop-in replacement) and lower the sensitivity so it mated better with my Modulus 2A.
Magic for about $300!
I got reasonably good results with a Bedini 25/25 but would probably use tube amplification today.
I know everything Ralph has said in this thread is dead-on accurate (as always).

It really makes me wonder how some people (some people who DEFINITELY know what music sounds like such as Chesky) power their Quad 57s with the ASR amp. The Emitter is, indeed, a class 'voltage-paradigm' solid-state amp, with power output nearly inversely linear to impedance. Based on the Quad's impedance plot, it should sound terrible, but apparently it sounds excellent and perfectly balanced.

(6Moons also attests to this in their report on Robin Wyatt's system.)
I meant to say "CLASSIC 'voltage-paradigm' amp".

And I also meant to say "power output nearly inversely linearly proportional to impedance". But, heck, everybody figured that out.
Hi there I've run ESL57's both single, stacked and with sequerra ribbons with Quicksilver 8417's. I got much better bottom end when I ran them as a single pair by putting them on stands about 18-20" off the floor and tilted up so the panels were more vertical. Better bottom end and much larger soundstage. You might like to try this.