Solid State Amps for Quad ESL 57?

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

http://www.atma-sphere.com/papers/paradigm_paper2.html

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.