DCtoDaylight;237203 Wrote: > I guess it depends a bit on your definition of digital... > I would argue that Class D amps are digital in their core, where they > use discreet voltage level shifting to represent the analog signal, > either on or off. This is a digital modulation of the power supply, > not an analog modulation. They are analog at their outputs, where the > reconstruction filter has converted the PWM (Pulse Width Modultated) > signal back to a continuous signal. > > Cheers, Dave I've always seen PWM as mostly analog. The information is impressed on the PWM waveform by varying the timing (duty cycle). While many schemes of generating the PWM waveform impose some quatization limitation due because they have discrete steps in timing, but PWM itself imposes no such quantiztion limit. That is, there is no theoretical limit to how small of a time can be expressed in the waveform. I think a quantization limit is centainly a major critereon I use to ditiguish digital from analog.
However, PWM, like PCM, relies on a reconstruction filter, so it shares certain aspects, such as bandwidth inherently limited by the PWM frequency, much as PCM's bandwidth is limited by the sample rate. Not to mention audible and/or measurable effects of the filter. -- Timothy Stockman ------------------------------------------------------------------------ Timothy Stockman's Profile: http://forums.slimdevices.com/member.php?userid=8867 View this thread: http://forums.slimdevices.com/showthread.php?t=39504 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
