[sdiy] Digital audio demo on Youtube

[rsdio at sounds.wa.com]

On Feb 18, 2014, at 14:24, Neil Johnson wrote:
> The output stage of the Roland R8 kind of approximates a Pulse
> Amplitude Modulated output, with a single PCM54 DAC feeding eight
> 4th-order (-24dB/oct) low-pass filters through 74HC4051 demuxers.
> That's better than a ZOH, since each output gets a short pulse in
> round-robin fashion.


Hi Neil,

Are you absolutely certain that the 74HC4051 is not followed by op- 
amp buffers with capacitors on the inputs, making them S&H stages? I  
don't have the Roland R8 schematic available in my collection, but  
the 4051 is often part of a S&H mux. If the R8 does return to zero  
while the other channels are processed, then I'd like to take a look  
at how they implement that return-to-zero circuit.

Brian Willoughby
Sound Consulting