Re: [Alsa-user] OT: Reference class-D amplifiers

[Alien <ali...@us...>]

Op dinsdag 23 augustus 2005 21:18, schreef Philip Prindeville:
> fons adriaensen wrote:
> >On Tue, Aug 23, 2005 at 12:41:32PM -0600, Philip Prindeville wrote:
> >>fons adriaensen wrote:
> >>>??? The input to that comparator would be an analog signal.
> >>>Also the only advantage of 'switching' amplifiers is their
> >>>efficiency. For quality I'd choose an analog one.
> >>
> >>That's one advantage.  The other advantage is you can run them at
> >>very high frequencies...
> >
> >??? They tend to get worse at higher frequencies. They are perfect
> >at LF, e.g. for driving large PA speakers, where you need lots of
> >power.
> >
> >>you can't do that with A or A/B amplifiers
> >>because they don't operate well in the cut-over area (when they
> >>switch from push to pull and vice versa) and because of the
> >>hysteresis when making that transition.
> >
> >That may have been the case 30 years ago when people used slow
> >power transistors (2N3055 and the like) in audio amps. The problem
> >has been largely solved by some innovative topologies developed in
> >the 70' and 80' (the Journal of the AES used to be filled with
> >articles on that subject at that time), and of course by faster
> >transistors and mosfets. Crossover distortion is a thing of the
> >past, at least in an amp made by a competent designer.
>
> I was thinking not so much of switching delays, as limited speed in
> high resolution D/A converters...
>
> With a class-D you're doing a pseudo 1-bit conversion...
>
> Anyway, let's not bog the list down in arcane discussions about
> class-D amplifiers...  Besides, I'll probably just show how hopelessly
> out-of-date my knowledge of the subject is.
>
> So how about it?  Anyone know of any decent barebones amps or
> sound-stage processor/amp combos?  If it is flashable so that new
> decoders (for DTS-xxx in the future, or whatever else might come
> out) can be downloaded, that would be a win.

why don't you draw yourself a schematic and build it yourself? at least you=
'll=20
know specifically what it'll be.

class-D amps certainly aren't as difficult as any decent analog amp. and th=
ese=20
days, who cares about high frequency, i mean, do you must have perfect musi=
c=20
for your dog???