Solid state design options...


What are the importance (to you) of these design options:

1. Zero Global Feedback
2. Fully Balanced Architectrure
3. Output Class (A vs. A/B)
4. Capacitance / Instantaneous Current Delivery
5. Dampening Factor

Any other ones that should be put into the mix for discussion?

I've been doing some reading where pundants claim these are very important considerations, and some who say they are nothing more than marketing gimmicks.

Thoughts?

I know...You should listen to the amps and let your ears guide you. That is a given, so those replies are not needed.
128x128nrenter
If only it were this simple... I have heard amps with negative feedback sound better than ones without negative feedback and vice versa. Same goes for class A versus AB and balanced versus single ended. As far as capacitance and dampening goes it really depends on the type of speaker you are using. As with most things design, execution and application are actually more important.

What I have found is that lower powered amps (including tube amps) generally sound better than higher powered amps in the same price range and if power is not an issue.

Ask the manufacturer of your speaker for amp recommendations.
How about the Belles 350A which is almost a purely class "B" design. It has a ultra high damping factor. Give one a listen if you get the chance or check out the review on Sounstage.com
Also, in the above discussion, a goodly number of amps use a cap to block DC on the input. This, to me, imparts a slight change in the sound for the worse. It seems input blocking caps have been substituted for DC servos (I know it's cheaper to do.) Also, as stated above, many amps go just a few watts into class A then crossover. With this, waveform distortions can occur. The positive and negative half cycles don't match up.
What i'm saying here is alot can happen to influence the sound of an amp besides the above listed things.
Why do people love tube amps---most of them stink on the test bench in any of these parameters. Most tube amps have a damping factor of around 20 or less! Could it be we like the "Distortions" a tube amp produces? (they sure test like crap!)
All the discussion points to one thing. Trade-offs for the typical audiophile amps. They were all optimized for a few particular things but not everything and they can't be due to cost consideration.

It's possible to design and build a 1000W/ch amp class A, balanced, zero-global feedback, balanced and high current delivery, but it will probably cost a quarter of a million dollars per channel and the size of a sofa.

So all these compromises designer made will basically force the marketing to emphasize specific strength which usually make all these terms unimportant and impossible to compare one on one.

If you are amp buyer, don't take these terms too seriously. If you are an amp designer, that's a complete different story.

BTW, if you can't tell yet, I am by training an eletrical engineer.
I am very picky. I own Krell.
I have no idea about any of these designs as they relate to any of the Krell amps that I now own or have owned in the past.

Buy a good amp from a good company.
Actually I bought great amps from a great company.

Just my 2 cents.

Richard
1, 4 and 5 are bare minimums for a nice amp. 2 is cool if you can balance the entire signal chain. 3 is nice if you can live with the heat and the electric bill. If you dig spec'ing out solid-state amps, compare the number of output devices/channel and the amounts of distortion and noise. After a while you'll get a feel for where the corners were cut.