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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
kijanki's avatar
kijanki
4,443 posts
 
Mapman, Woofers have only one invention - lack of suspension (spiderweb) compensated by large diameter voice coil mounted to flat disc in place of dustcap. It makes membranes lighter, faster and stiffer. Midrange (6.5") uses, in addition ferrofluid as a suspension. Midrange is absolutely breath taking. Tweeter is so well integrated that I cannot really tell transition from midrange.

http://hyperionsound.com/Images/HPS-938%20review.pdf
mt10425
1,138 posts
 
I'm happy to see Atmasphere has joined the party. Perhaps information less subjective is in the future of this thread.
kijanki's avatar
kijanki
4,443 posts
 
Atmasphere, It make little sense to seek very high DF for better damping (assuming that speaker needs it) when inductor in series with the woofer has most likely resistance of 0.1 ohm limiting DF to 80 even with perfect amplifier.
atmasphere's avatar
atmasphere
12,063 posts
 
Correct! IMO the damping thing is way over-blown.

I found that article:

http://paulspeltz.com/tomcik/index.html
dracule1 OP
1,085 posts
 
Atmasphere, I've seen you write about how bad odd order harmonics can sound (ie, subjectively bright and hard) even at very low levels. Can you please specify at what level are odd order harmonics perceived as unpleasant? I don't recall you ever giving an actual number.

I have owned your M60 amp which I think uses a 2 dB of NFB and compared to a pentode, class AB, tube amp with 20 dB of NFB. Everything else in my system was constant. The volume level was as close to even as I can get them with SPL meter, and the volume ranged between 85 to 90 dB max during the comparison. The speaker had minimum narrow impedance band of 5.8 ohms and was 90 dB efficient. By your own words, 20 dB of NFB is considered excessive. However, I did not hear any excessive hardness or brightness in either amp. Both were very smooth in the midrange and treble regions. How do you explain that?
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