[sdiy] using a dac as a digitally controlled amplifier

[chris]

The problem with that may be that (AFAIK) multiplying DACs only multiply
unsigned values.

I once did a crude attempt with an MCP4922 (two multiplying 12 bit DACs).
I level shifted the input so that ground level was at 2.5V. Varying the
DAC value also shifts 2.5 input ground level. 
IIRC, I usedone channel for variable level shifting. 
Messy

Could be possible with a DC offset and AC coupling after the DAC

Chris



On Sun, 4 Aug 2024 13:13:42 -0400 Benjamin Tremblay via Synth-diy
<synth-diy at synth-diy.org> wrote:

> Is there any practical application for synthesizers to pass an analog signal in as a reference voltage to a DAC?
> 12 bit DACs are pretty cheap these days, but VCAs aren’t expensive either. 
> Aside from cost, why would I want to use a DAC as a “DCA”? 
> 
> I can imagine making a state variable filter using a dual DAC as the ‘gain' stages.  
> It’s the kind of thing I would try just to see how well it worked… 
>  
> I suppose you inject one or more DACs into an oscillator to directly control pitch and waveform, some kind of DCO where stability and simplicity are cost-effective.