[sdiy] using a dac as a digitally controlled amplifier

[Tom Wiltshire]

The Synclavier used an 8-bit MDAC for the volume envelope, and another for the overall level, I think. The digital stepping intrinsic in this process is now a cherished part of the character of the sound!

The Synclavier used a 50KHz sample rate, but I have no idea if that applied to the envelopes too. It may have done. It was a heavily "overbuilt" machine in many ways, and the price reflected that.

> On 4 Aug 2024, at 23:23, Mattias Rickardsson <mr at analogue.org> wrote:
> 
> Interesting thread.
> 
> Do these vintage examples use static amplification factors in their MDACs, or do they allow the digital value be modulated by envelopes and LFOs?
> 
> If they do modulate stuff, how is the result in terms of zipper noise etc? Unlike when using a VCA controlled by a CV generated from the very same DAC, there is no way of smoothing out the digital irregularities in the MDAC case. Only perhaps keeping the sample rate above audio (which they probably didn't do by then) or to use clever noise shaping techniques (which also seems unlikely).
> 
> /mr
> 
> Den sön 4 aug. 2024 20:48Gordonjcp <gordonjcp at gjcp.net <mailto:gordonjcp at gjcp.net>> skrev:
> On Sun, Aug 04, 2024 at 06:26:06PM +0100, Tom Wiltshire wrote:
> > The Synclavier used DACs for VCAs like this too, fed with audio from other DACs. In that case it was a way of avoiding doing multiplies in hardware and not losing any resolution.
> > 
> 
> The Ensoniq DOC chip uses the same trick for the same reason.
> 
> -- 
> Gordonjcp
> 
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
> View archive at: https://synth-diy.org/pipermail/synth-diy/ <https://synth-diy.org/pipermail/synth-diy/>
> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy <https://synth-diy.org/mailman/listinfo/synth-diy>
> Selling or trading? Use marketplace at synth-diy.org <mailto:marketplace at synth-diy.org>
> ________________________________________________________
> This is the Synth-diy mailing list
> Submit email to: Synth-diy at synth-diy.org
> View archive at: https://synth-diy.org/pipermail/synth-diy/
> Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20240804/34913b26/attachment.htm>