Solid State Amps for Quad ESL 57?

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.

Thanks
Sean

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?