Bandwidth Limitations Of Class D Amps??

-3db means there will be phase shift problems all the way down to 10khz.
Why some say the upper mids and top end is hard could mean the the filtering is too high and letting the nasty switching noise intrude.
Why some say the upper mids and top end is bland and opaque could mean the filtering is too low and effecting the harmonic content of the upper mids and highs.

This is why you'll see class d manufactures bringing out different versions or mk 1 2 or 3 They change the filtering to the above to either or a combo of both, which I think sounds the worst.
Once technology get more advanced and they invent components whith much higher switching frequencies so they then can use the filter so the effects and phase shifts of them are well out of the audible range then Class D will compete with the good of linear amps, until then it is comprimised, but great for subwoofers.

Cheers George

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.

After listening to them and also measuring them, they do not come up to the sound quality or measurments of good linear amps in the upper mids to trebble.
I conceed they are great value for the money. But if one is into great sound and is an audio buff this is then where they fall down.
In the future when the switching frequency can be much higher then I can see even I will change over to them.
But at the moment I will stick with linear until that happens, and it will happen as technology advances with the high speed switching frequency.

Cheers George

"After listening to them and also measuring them..."

Hi George, which are the class D amps that you have listened to and measured?

Thanks, G.

They all have the same characteristics with their mandatory switching filters on their outputs. And the ones that have smp power supplies have even another problem to deal with, regarding noise.
I'm not going to point the finger at any brands as that would be against forum policies. And I have been warned a couple of years back for it.
All you have to do is listen to them against good linear amps on a revealing system. Then look at any graph/tests done with power output vs thd in the higher audio frequencies and see how it rises very quickly vs lower frequencies, look if you can get it current output in the upper frequencies vs the lower frequencies. Then also if you get get them the phase shift from 10khz to 20khz. And then for good measure the noise figures in the upper frequencies vs lower.

" Class D " and the virtues of, a guru roundtable discussion setup by Absolute Sounds

http://www.stereo.net.au/forums/index.php?/topic/50607-class-d-and-the-virtues-of-a-guru-roundtable-discussion-setup-by-absolute-sounds/#entry843343

Cheers George