What is wrong with negative feedback?

"There are good sounding components using feedback and no feedback, which is simply more proof you need to listen to the component, because the component really is an extension of the skills and philosophy of the designer, and there are good skilled designers employing both methods."

I think this is the bottom line practically for most.

The caveat is you cannot listen to a single component alone, only a system with all the required components (source, amp, speaker/room) together. A single listen can only tell you what each component is capable of, not how good or bad each piece is or sounds. To sort it all out requires doing your homework and listening to as many combos as you can over time.

"There are no known speakers requiring a damping factor of over 20"

I am not aware of any speakers that publish damping requirement specs. What are some?

I am aware that different designs benefit differently from varios damping factors, but not that vendors specify damping requirements for their speakers in that determining which combos sound good is often a largely subjective determination?

You guys are in way over my head! I can sort of follow the tech talk but have no way to translate that into results regarding actual sound quality to expect via the various design approaches.

I'm curious to see the bottom line in the end ie what key points relating to feedback and sound quality you two agree and disagree on. Perhaps also if there are any amps most might be familiar with that are good representatives of how the different technical approaches sound.

Atmasphere,

I suspect it would be hard to set up any meaningful comparison of an amp alone in that an amp cannot produce music alone without speakers. The results could vary widely depending on speakers used, personal preferences, and all the usual culprits that result in different strokes for different folks.

My gut feel is that as you say, its all in the implementation and there are many ways to make tasty soup.

The Bel Canto ref1000m2 Icepower Class D amps I am using on my larger full range OHM Walsh omnis seem to be able to go as loud as desired without an edge on most good recordings.

These amps are high damping factor which matches well to the OHMs, so I suspect there is NF applied, but not sure. If loudness cues are more present as a result, I'm not sure that it is significant enough to matter.

I also use Triangle and Dynaudio monitors on teh same system. Monitors in general will not fare as well with orchestral music at high volumes (at least not without a sub of some sort to offload much of the work), so I can say that the speakers are definitely a factor as well.

When I first heard the IcePower amps in my setup, the difference in the nature of teh sound from anything I had heard prior was most startling. It was most apparent in that major volume adjustments seemed to have comparably little effect on volume, though the SPLs were clearly increasing as expected.

My observation of how the IcePower amp sounds as volume is increased seems consistent to me with what Ralph describes as the benefit of not using feedback and loudness cues. Most really good systems I have heard over the years tend to behave this way more or less I believe.

At the same time, Icepower applies negative fedback clearly. So I have to conclude that the IcePower amp has achieved a lot of teh benefits that Ralph attributes to no feedback in its specific implementation.

If so, another reason why Icepower/Class D can be considered a major innovation in home audio along with the other advantages.

"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!

"Now of course you can imagine that one might do that with a more efficient speaker because it is possible, but really the limiting factor with the less efficient speakers was that the loudness cues made it uncomfortable to turn it up the volume any higher."

Hmm, I'm under the impression amp clipping generally becomes more of an issue at higher volumes with less efficient speakers?

I'm assuming that you run these with one of your tube amps, which would minimize loudness cues when distorting? All amps distort more at higher levels, correct? The question is in what way and to what extent the distortion is audible. For a given amp, this would occur sooner at lower volume with a less efficient speaker, all other factors aside, right?