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RE: Distortion and Audibility...replay.

"Why do you consider this ultra high power approach to amplifier design a compromise in and of itself?"

Not ultra high power per se but how it is mostly achieved (ie. many many transistors all of which are highly non-linear that are run in a not particularly linear mode of operation and then with high feedback to "linearize" the whole mess). I don't think throwing more and more highly non-linear devices at a problem will make it more linear.

"It seems to me that if sufficient negative feedback is employed this amp could potentially be as pleasing as any other solid state amp"

That is exactly the problem with most SS amps I have heard...not pleasing! The MCs are no exception...they don't sound particularly good. The amps I have heard that were pleasing invariably had low to no feedback and sounded good "despite" bad measurements (The darTZeel amp comes to mind). Not more feedback amps (like Halcro, which to me sounds bad in all setups I have heard them so far) but less is what I have heard deliver great sound. Also, the approach with ultra high levels of negative feedback has been tried many times and to my ears so far has never really been successful. In fact the whole current backlash towards tubes and such is in response to the bad sound of high feedback SS amps. Despite what many here think it is not a fetish but an observation by many listeners that these older concepts when well executed simply sound better. The correlation work I think starts to illustrate this.

I was once a high power SS amp guy (I had a Simaudio Moon W5 and before that the Simaudio Moon Celeste W4250, which was a beast and Threshold and Sumo etc.) Then I went to lower powered Class A SS (Sumo 9) Then to Class AB tubes, Then to Class A SET, Class A/AB hybrids (stayed there for a long time because sound close to as good as SET but with more drive), Class AB OTL (ran too hot only if you like Sauna! But the sound was very good) and now I am at Class A SET hybrid (only one brand that does this that I know of and the best sound I have heard so far...the secrets in the output transformers of this particular amp...very linear compared to most others in the bass).

This transformation came about by listening to lots of amps and systems and observing what the different parts were contributing to the sound and what happened when that part was changed. I slowly realized that when I heard a sound that really reminded me of live music it was from a system with electronics that were low in feedback, which usually means having tubes somewhere due to their suitability for simple more linear circuits.

There are many misconceptions about SET amps and one of them is that they cannot have good controlled bass. Its not true because there are examples to the contrary.

Most SET amps sound badly controlled in the bass not because of their low power or damping factor (this is for the most part a red herring...look at the article in audioholics that discusses damping factor and it will be clear) but because they have a crappy, saturating output transformer that is making 10s of % distortion in the bass. This makes the bass sound fat and slow and poorly controlled. Also, many of these crap transformers severely roll off the highs above about 12Khz, although this is less important because most people can't hear above 15 or so Khz. Two SET amps with great bass are Lamm and KR Audio. Both have very linear transformers in the bass (ie. less than 1 or 2% in the bass distortion, which is essentially inaudible) and relatively extended highs. Damping factors are around 5 or 6 for both amp types. Lamm is all tube Class A and KR audio is hybrid SET Class A (tubes only on the output and JFET and MOSFET elsewhere...very simple).

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