What is wrong with negative feedback?


I am not talking about the kind you get as a flaky seller, but as used in amplifier design. It just seems to me that a lot of amp designs advertise "zero negative feedback" as a selling point.

As I understand, NFB is a loop taken from the amplifier output and fed back into the input to keep the amp stable. This sounds like it should be a good thing. So what are the negative trade-offs involved, if any?
solman989
Unsound - I remember Ar_t posting on the subject of switching amps. I don't know about TacT now. At the time I bough my Icepower based amp I read opinions on Icepower and Hypex. Both configurations (Full Bridge vs Half Bridge) have good implementation for instance Hypex based Channel Island amps.

Mapman - I also observed that listening at low volumes with Icepower is very good. I know that part of the problem is our hearing but I enjoy very good and clean sound (with very articulate bass) at low levels without any loudness correction. I cannot explain it. Do you experience the same?
"Mapman - I also observed that listening at low volumes with Icepower is very good. I know that part of the problem is our hearing but I enjoy very good and clean sound (with very articulate bass) at low levels without any loudness correction. I cannot explain it. Do you experience the same? "

Yes, bass is very articulate at all volumes. That and the loudness behavior I described above are perhaps the two biggest differences I hear on my system with icepower compared to prior SS amps.

The loudness perceived compared to actual SPL was most dumbfounding at first especially in that teh IcePower amp power spec is 4X what I had before (500w/ch into 8 ohm compared to 120w/ch prior). Its almost like the additional power is utilized to flush out the music, kind of like blowing up a ballon, as the volume goes up yet the perceived loudness does not increase so much.

Kijanki, one other thing, with my particular speakers, the high current and efective doubling of power into 4 ohms helps produce a natural balance in the bass which also helps at low volume whereas with some amps, the bass is relatively leaner. Toss in teh articulation in the bass provided at all levels then and you have quite a winning combo that not only delivers a detailed low end, but also allows higher frequency details to come through to boot. Very satisfying to listen to! Articulate, detailed and "musical". Very hard for me find fault at present, which is a very nice place to be!
The loudness perceived compared to actual SPL was most dumbfounding at first especially in that teh IcePower amp power spec is 4X what I had before (500w/ch into 8 ohm compared to 120w/ch prior). Its almost like the additional power is utilized to flush out the music, kind of like blowing up a ballon, as the volume goes up yet the perceived loudness does not increase so much.

This sounds like there is less odd-ordered harmonic generation.
Atmosphere said "06-25-10: Atmasphere
Acoustat6, yes, sometimes I do. Most music does not demand it but some does: The Verdi Requiem, on the Soria box set (RCA) is a good example of vinyl being put the limits, and stereos too. If you play the quiet spots at the correct volume, the peaks will be at 115db."

Hi Ralph, If you listen to the Verdi Requiem at peaks to 115db (which is an impressive level for any system) then, and since we all know that rock is supposed to be even louder than an orchestra, how loud would you listen to Cream live or other "loud" rock?

Because you said, "IOW, a proper stereo should lack loudness cues, such that you can approach the same volumes in your room that the real live music could."

Then just how loud do you listen to rock on your system to approach what a live rock concert does. Its gotta be louder than a recording of Verdis Requiem!

Bob
Acoustat6, that's true. My system can play so loud that prolonged exposure can result in damage. But playing rock as loud as it is often performed has a bugaboo: most rock recordings are anything but live! Quite often the guitar amps have only 15 watts in the studio, so who is to know how loud such a recording is to be played.

I have a white-label Vertigo press of Black Sabbath's 2nd LP (Paranoid), which is an amazing recording and one that can bring most systems to their knees in a heartbeat. You play it loud, but even that one is hard to tell how loud it should be played.

I play in a rock band, and recently we did a memorial show where we were the only band on the bill that was not metal. The club we were playing in was a metal club. It was on that night that I discovered that metal bands don't play all that loud. The most powerful guitar amp we saw that night only made 25 watts. They rely on the PA.

So- how loud is that supposed to be? Rock is always tough because there is no good answer for it.