On a sunny day (Tue, 23 May 2006 16:10:17 -0500) it happened "Dr.Death"
wrote in :

"Jan Panteltje" wrote in message
...
On a sunny day (Mon, 22 May 2006 19:02:24 -0500) it happened "Dr.Death"
wrote in :


Class D audio amps are only designed for low frequency as they would sound
like crap for the higher freqs.

Can we have some math please?
Or did you design the one for the full audio range?

No, but don't you think they would be on the market if it were feasible? Try
hooking one up with a high pass filter and see what it sounds like.

Maybe you dunno it, but most modern cellphones use PWM audio amps to extend
battery life and increase audio power.

As I mentioned, it is just math.
Say you wanted (more then a cellphone) and go to 20kHz as highest freq.
You'd have to switch a bit higher, Niquist applies, but let's use 320kHz.
So your lowpass would have to start falling of after 20kHz and be say -70 dB
at 200 kHz.

20 40 80 160 230 = 4 octaves, so 70 dB over 4 octaves.
What is your problem?

The real problem is keeping the RF from radiation via the speaker leads
in the long wave band....
Sony had (or maybe has) some HiFi PWM audio amp.

You can NEVER make a rule (like you say), PWM has distortion at high
audio frequencies without bein gspecific about the design (electronics).