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In Reply to: My criteria for a POTENTIALLY good sounding amp posted by morricab on June 18, 2012 at 07:22:50:
The hyper focus on negative feedback and "tube sound" is a total red herring. I was listening to Kenwood and Accuphase high speed amps way back in the day when Dr. Ottala's work was still the "holy grail" of audio. In the real world, amps that have a flat response out to 500 khz are useless. The claimed audible improvements, if they even exist, are slight. What is far more problematic is the instability and lack of output current capability that wide bandwidth designs create. Moving coil loudspeakers (the vast majority in existence) are low impedance current driven devices that are typically not compatible with tube voltage amplifiers that possess high output impedance. Wide variations in a speaker's load impedance will always produce audible anomalies in the net response of a high output impedance amp/loudspeaker combination. And no matter what tube fanatics say, that is not a good thing. Their suggestion that speakers which possess wide load fluctuations are not "properly designed" is ludicrous.
Moderate use of negative feedback in a good Class AB design has no audible signature. And because transistors typically have much higher gain bandwidth products than tubes, some feedback is necessary. Threads like this are full of uninformed blanket statements that have little or no real world value. If negative feedback induced "time smear" were such a catastrophic problem, Kenwood would still be making and selling a version of its L07MkII - an amp I once owned that experienced wide band melt down. While it was a clean, noise free amp - I could not tell an audible difference between it and the Class AB Threshold and Crown that ultimately replaced it.
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Follow Ups
- RE: My criteria for a POTENTIALLY good sounding amp - villastrangiato 08:50:32 06/27/12 (9)
- Moderate use of negative feedback - Feanor 05:45:40 07/01/12 (8)
- RE: Moderate use of negative feedback - morricab 01:01:53 07/03/12 (7)
- Pass makes a good case for ZERO negative feedback ... - Feanor 05:58:10 07/03/12 (6)
- RE: Pass makes a good case for ZERO negative feedback ... - morricab 01:13:22 07/04/12 (5)
- The basic issue is the audibility of distortion - Feanor 07:26:45 07/05/12 (4)
- RE: The basic issue is the audibility of distortion - morricab 14:14:05 07/05/12 (3)
- I guess I'm just deaf - Feanor 10:55:37 07/06/12 (2)
- RE: I guess I'm just deaf - morricab 15:07:49 07/06/12 (1)
- I'll reread Geddes, Cheever, et al. a few more times - Feanor 16:21:33 07/07/12 (0)