Bandwidth Limitations Of Class D Amps??

George,

You did not answer gc's question or address my points.

If you look at Stereophile published bench measurements for Class D switching amps (say Bel Canto ref1000m for example) versus traditional class A/B (non switching amps), I think you'll see examples of what Kijanki referred to.

I would expect the switching frequency used/possible given the current state of the technology to be the technical limitation with switching amps. With current technology, effects appear to be measurable within upper limits of human hearing, ie 20Khz.

All amps have limitations. But with non-switching amps, the limitations are due to other design factors. Still, I believe many are capable of measuring flatter to well beyond 20Khz.

Of course what is measured may or may not be an indication of what is actually heard, especially when it relates to the extremes of what humans are able to hear. The upper limits of what humans can hear is probably still the weak point for Class D switching amps. How weak or how much it matters is debatable I suppose, much like what is the effects of CD redbook sampling parameters. Newer CLass D amps using newer technology might push switching frequency up higher than what was possible even just a few years ago. Have not seen measurements on those yet so not sure if the is the case (yet).

Realize that switching frequency spec of a switching amp would seem to set a clear theoretical limit to what is possible with that design in terms of frequency response. But alone it does not determine sound quality, even as measured. It may determine an absolute limit in theory, but the reality is many factors affect amp performance, switching amp or not. Specs are informative but alone do not tell the whole story. Only our ears can do that and each story will probably be a bit different as a result, especially when it is differences in the fine details of what is heard that is in question.

"My Gilmore Raptors are -3db at 60khz"

Arh, are those Class D amps an end to end proprietary design by the maker or do they incorporate another company's Class D amp modules?

ANything more to back up the published specs?

GEorge,

You might be correct regarding the theoretical weak aspects of Class D but my experience is that they ARE competitive with other amps, not just good for subwoofers. Many users and reputable reviewers would agree.

All designs have flaws/imperfections, switching and otherwise. Gotta look at the whole picture, not just one aspect of one particular design.

It's like when Ralph from Atmasphere focuses on downside of negative feedback and says it can never sound like music. Many SS (and tube) amp owners might disagree, though his theoretical argument seems sound. One aspect of design theory only tells a part of the story though. THere are many factors that go into a good design. Most engineers think their way is best, and few do everything exactly the same, so I do not hold that against a good engineer that has done their homework.

Switching frequency just makes that aspect of Class D design very straightforward to quantify in comparison to many design aspects of non switching amps.

That is an advantage I would say in terms of being able to clearly identify an actual performance bottleneck specification with CLass D, similar to how sampling resolution defines limits of digital media.

Do non switching amps have any parameter that is similarly definitive? Not sure. That make comparisons hard and more subjective, not necessarily a good thing!

I do agree that as switching frequencies get higher, issues will diminish further. That bodes even better for the future of CLass D and seems to be happening already with newer Class D modules I have read about, like Abletec for example, however I have not seen any reviews from pubs or individuals on those yet, so the story is still out.

"Which means "A personal stake or involvement" in that amp."

So by this logic, we can only discuss things we have no involvement with? That sounds like fun!

By this logic, nobody would discuss anything anywhere because they have a "personal stake". That would include George and his favorite amps as well.

Crickets.....

My only personal stake in CLass D is I tried one, liked it and have not had any need to look further.

I look forward to buying even better ones possibly even for less down the road if needed as the technology continues to improve.

I have lots of years of experience and have heard a lot of gear at all price points and of many designs over the years. That is how I get my frame of reference for what sounds good or not. I also look at specs and bench measures and choose my poison.

ANyone who can read can determine for themselves if they think Class D is competitive in the high end already these days. I am willing to bet that as time goes on, more and more people will continue to chose to go that route and be very happy they did.

" But to be honest, I only have about $65k-$70k in my system, I don't have a high-end system."

That's funny!

If Class D amps are even in the discussion for a system in this price range, high end or not, I would say that's another good indicator that they have arrived.

FWIW I have ~$10K invested in my main system, and slightly less in other gear I use concurrently in various rooms. Most people I know would probably label it "high end" if they cared. That is what I payed, not retail, but I am very value conscience and have bought a lot but not all of my current stuff used or discounted via vendor trade-in programs, etc. I will say I think I know and like quality sound when I hear it and leave it at that without getting into details of what that means to me. My Class D amps list for $6K new, FWIW and represent my single biggest monetary investment in my system, though my speakers would list for about the same amount..