Revisiting the stereo/receiver research for purchase

[Win]

quote:

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Originally posted by keith:
A well designed amplifier, used within its design limits, will to all intents and purposes sound the same as any other. There's an easy $10,000 waiting for someone who can prove otherwise:

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I didn't read through all of it, but clearly he is talking about automotive amps since he limits his entrants to a B+ of 14 volts. Modern bipolar transistors and MOSFETS will be operating at higher voltages.

He also won't let anything go into nonlinearity, and he puts a number of ambiguous specs such as "non excessive" noise. It seems to me he wants to exclude all the parameters that create audible differences.

It reminds me of the old adage we use in trial practice: never trust any test you haven't rigged yourself.

 

[keith]

quote:

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Originally posted by Win:
He also won't let anything go into nonlinearity, and he puts a number of ambiguous specs such as "non excessive" noise. It seems to me he wants to exclude all the parameters that create audible differences.

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A non-linear noisy amp will be easy to tell apart from one that doesn't have those special 'features'. Any well designed test would of course eliminate the possibility of detecting an amplifier by it's inferior design, and that is clearly stated in the goals of the test.

I've had my run of high end and mid and low end amplifiers in my home. Designed some of them, borrowed some of them, and purchased some of them. Some are easy to detect because they are flat out bad. The well designed ones, at all price points, are incredibly similar when used within their limits. Similar enough to be indistinguishable in blind testing, at least to my ears. The classic Doug Self book, "Audio Power Amplifier Handbook", pretty much details where the amplifier performance parameters need to be for the artifacts to be inaudible. It's not a cookbook, but more of a pragmatic approach to real world design problems.

 

[1sttruck]

My older NAD receiver has pre-out / main-in connectors, so you can use it as a power amp, or just as a preamp/tuner, either with other components. I started with the NAD, a turntable, and some Spica TC-50s, and later on picked up a tube preamp as it had a nice phono section. Eventually I brought home a bunch of power amps, Adcom, Conrad-Johnson, NYAL Moscodes, etc., swapped them in an out over the course of an evening, and settled on a smaller Moscode. Now I'm back to using the NAD as it's easier for the family to use with DVDs, CDs and the TV.

 

[Auto-Union]

My pre-amp is NAD with the semi-parametric tone controls. I like it. A pre-amp with full parametrics is a nice item.