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Negative feedback Amp=more faithful reproduction?

Negative feedback (NFB) vs zero negative feedback (ZNFB). There seems to be unsubstantiated contention that ZNFB amps sound more realistic. I know this is an age old debate favoring the ZNFB design, but I think most audiophiles have never bothered to look into this matter and believe the advertisements and proponents of zero NFB design. I have been in that camp until recently. My own experience and research into articles on this matter leads to me believe NFB is needed for faithful reproduction of music. I'm not saying NFB design is more "musical", which is a highly subjective term and usually means more euphonic or colored. I've posted a similar question awhile back, but I was hoping we can have a more evidence based discussion on this matter. Perhaps, we need clarification of descriptive terms we use to describe sound. My contention is, in general, NFB designs produces a more accurate or faithful reproduction of music than ZNFB designs. Here is a very good article on feedback and distortion:

http://sound.westhost.com/articles/distortion+fb.htm
dracule1
roscoeiii's avatar
roscoeiii
1,155 posts
 
I am by no means a technical expert and have enjoyed both NFB amps and ZNFB designs, but I did want to note the perhaps it is a good idea to bring the human brain into this conversation (I am a neuroscientist, so I can't resist). Namely, it is fine that we are able to measure amps on the bench, but we also need to acknowledge that our ultimate enjoyment of an amp-speaker combo is based on how our brains process the signals that reach our ears. Psychoacoustics plays a major role that can't be overlooked, such as determining what frequencies we can hear most acutely and which order of distortion is more noticeable.

Also lurking in each individual brain are personal preferences. Nelson Pass' First Watt line of amps is a great example of a wide variety of design choices that are intended to both give a good match with certain types of speakers and to provide different flavors to account for different listener preferences.
lloydc's avatar
lloydc
739 posts
 
it's adjustable on my amp (Mesa Baron,) so it is easy to hear the differences. I have ears, so I do not really care about the technical rationale. Some music sounds better with a little NFB (primarily studio produced rock), but most music sounds better without any NFB, at least with my system. In general, the sound is a bit less "alive" with NFB, but if a record is made with lots of compression, that hardly matters, and other factors come into play.
charles1dad's avatar
charles1dad
10,236 posts
 
I 'm glad to see most of the replies are based on common sense and actual listening experiences.Which ever amplifier type sounds best to you, that's the one to buy. No need to cite this paper or that article to strengthen your preferences. I don't know why people need validation for their choices. For me, I'll take a well designed ZNFB SET amplifier anytime.It matters none at all if someone prefers something completely different, so what.Make a choice and stop worrying if others disagree. Different ears (and brains)will choose accordingly, imagine that.
Regards,
kijanki's avatar
kijanki
4,412 posts
 
Many people like sound with some distortion that makes it more alive (distorted guitar vs clean guitar). My Benchmark DAC1 sounded too clean at first but it doesn't anymore (learned to listen). Many accused DAC1 of sounding sterile. When they compared different DACs in studio Benchmark was the closest to live sound but not favored by most of testers. One person expressed opinion that all instruments sound separately while he likes them more "together" (sound blob?). Reducing NFB increases distortion making sound more "alive". It also reduces bandwidth making bright systems sound more civilized. In addition it increases output impedance making impression of more bass on over-damped speakers with SS amp. All is a matter of taste. I prefer super clean highly resolving sound with very tight bass, while others might prefer some distortion or noise with rounder bass, calling sound more "organic".
dracule1 OP
1,085 posts
 
Kinjanki well said. That had been my experience with NFB as well.

I'm not looking for validation. I've been in this hobby for close to 30 years and I know what I like. I'm searching for technical explanation of why we hear what we hear.

I have listened to SET amps paired with high efficiency speakers. There's no denying the beautification of the midrange which can sound glorious and involving. But in the long run I know it's the way things sound in real life. And I do understand why some gravitate to this type of sound.
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