Stewart Pinkerton wrote:
> On Fri, 30 Sep 2005 17:24:43 -0400, Jerry Avins <[email protected]> wrote:
>
>
>>Stewart Pinkerton wrote:

...

>>>Ahem, PWM isn't necessarily digital - remember the wonderful Sinclair
>>>X-10 amplifier from the mid '60s?
>>
>>No. please describe it.
>
>
> Class D amp using germanium small-signal transistors, rated at 10
> watts, actualy produced about 3 watts, rated at 0.1% THD at full power
> - unfortunately, those were switching artifacts which stayed at the
> same level regardless of output, so the whole thing sounded absolutely
> dreadful! Lasted for about a year on the market, and was followed by a
> whole slew of highly novel but ultimately trashy Sinclair products.
>
> Clive Sinclair (who didn't actually design the X-10) is a true
> innovative genius - who couldn't nail together two pieces of wood,
> never mind produce reliable electronic gear.

I'm glad I never had first-hand experience with it! Still, one could
make a case that a class-D amplifier is digital at least in some
respects. The amplitude at the switch is certainly quantized, and pulse
width also in many modern implementations. I will assert unconditionally
that *some* PWM applications are fully digital, and that it is a useful
digital encoding for some applications.

All that aside, the OP's assumption that compressed signals aren't (or
can't) be encoded as PCM is nonsense.

Jerry
--
Engineering is the art of making what you want from things you can get.
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