[sdiy] Delays and companders

Ben Bradley ben.pi.bradley at gmail.com
Mon Mar 4 20:23:28 CET 2019

It seems you've got a "good" voltage running the compressor VCA, you'd
just want to delay it and then put it in the expander. I don't know
how well BBD's carry DC, but adding another one to use for that is an
offhand thought.

Perhaps better is using a small microcontroller with built-in A-D and
D-A  to delay the VCA control voltage. The controller's clock can be
derived from the same clock as the BBD, so they would stay in sync
over various delay times.

On Mon, Mar 4, 2019 at 1:09 PM Tim Ressel <timr at circuitabbey.com> wrote:
> Hi,
> In making a BBD delay often a compander is used to reduce noise. One
> schematic had a clever circuit that used one rms-dc block to run both
> the compressor and expander VCAs. This would make sense in a non-delay
> circuit. But in a delay where the output is not time aligned with the
> input, is it the right thing to do? It seems to me you want completely
> separate compressor and expander circuits with their own rms-dc blocks.
> Say a pair of 4305s from That Semi. Or am I in the weeds here?
> --
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
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