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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
dracule1 OP
1,043 posts
 
The degree of feedback needed is dependent on speaker that is driving. You make a valid point. The designer purposefully built feedback into the amp.

I don't necessarily understand the article fully as my technical knowledge is limited, but I can recognize a well thought out article when I see it. I wanted start a discussion on this subject, and see what others had to say. Like I said, this seems to be the wrong forum. Many here are subjectivists and do not care about objective analysis.
charles1dad's avatar
charles1dad
6,996 posts
 
Mt10425 and others have given very thoughtful answers and points of view. Dracule,you say you are`nt seeking validation but you responses suggest otherwise.There is no technical explanation to support your position,it`s simply your own preference as to what sound you happen to like.There`s no objective determination to seek in subjective issues as this is.Regardless of what forum or subject heading you choose to post on, the results/replies won`t change.You prefer the sound of NFB amps for the reasons you cite, it`s nothing more or less than that.Being condescending(as though you`ve seen the light now and other have`nt) to those who prefer a sound different from what you consider to be right or more"accurate" is pointless.Mt10425 is`nt off topic at all.
Regards,
mapman's avatar
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mapman
15,679 posts
 
That is a very informative article as are many of the replies, as usual.

Only thing of value I can think to add is yes, practically, it is how the whole system functions together that matters, not specific design paradigms applied to specific components. There are many ways to skin a cat. That phrase could never be more true than it is regarding the details of ways to deliver quality sound reproduction. Each will chose their preferred solution. VEndors will obviously also chose their approach and any vendor worth their salt will believe in their approach 110%. CEtain design approaches that are more unique or innovative, like no NF and one of my personal favorites, Walsh drivers, done well, help to make certain vendors stick out in the pack, which is important if you are in a business for the long haul.

When someone comes up with the undisputed mathematical equation for why I like what I like, please let me know! I am waiting patiently.....
jwm
908 posts
 
So your amp sounds best to you when you dial in a little feedback big deal. It does not tell you that all amps should sound better that way. It is very hard to design an amp without feedback. My hutch tells me that if your amp were designed to sound its best without feedback and then give you the choice you would prefer no feedback. This goes back to the Manley amp that allowed you to listen to their mono blocks in single ended mode or push pull mode. I liked it better in push pull mode and then thought that single ended amps suck. Oh not true, you can't design a circuit to sound good doing both you need different transformers and parts. So you see my friend your conclusions on a simple rotary switch is not viable. You need to keep an open mind which at that time I did not and now do.
kijanki's avatar
kijanki
3,575 posts
 
Mapman, the question here is if NFB makes reproduction MORE faithful. Some answered that there is no faithful reproduction, which doesn't answer this question, while others stated they prefer sound of ZNFB which doesn't answer this question either. The truth is, that there is no SS amp (and very few tube amps) with zero feedback. SS amp by nature is a voltage source, and as such needs some form of negative feedback, at least for the output stage. The question is how much and that might depend on the load, your preference etc. It is undisputed fact, that even small amount of NFB widens bandwidth, lowers output impedance and reduces THD/IMD distortions. Does it make reproduction more faithful on average? I think it might. What sound you like has nothing to do with original question.

I'm working on this equation, you asked for, but it can take some time.
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