[sdiy] using a dac as a digitally controlled amplifier

[brianw]

On Aug 4, 2024, at 3:48 PM, Tom Wiltshire wrote:
> Ah, here it is - the Synclavier way of doing it!
> 
> http://www.500sound.com/SyncII/synthschem.jpg

A picture is worth a thousand words.

In that topology, it is easy to filter the Volume DAC output before it reaches the Envelope MDAC VREF input. Similarly, the Envelope MDAC output could be filtered before it reaches the Wave MDAC VREF input. This works because the waveform starts out digital, and it's amplitude CV coming in.

Unfortunately, if you feed the audio waveform in the VREF input, and use the digital sample value for the volume, then there'd be no way to smooth the volume changes with a simple analog filter.

Brian