[sdiy] Delays and companders

rburnett at richieburnett.co.uk rburnett at richieburnett.co.uk
Tue Mar 5 12:31:03 CET 2019

No, I totally hear what you're saying and agree.  Analogue feel 
definitely has its place.

It just seemed ironic to have a modern ADC + micro/RAM + DAC chain as a 
"supervisory circuitry" around an analogue BBD delay line just to delay 
the compander CV!  When a digital audio delay could be done with almost 
the same circuitry and remove the need for the BBDs and the companders.

I'm personally all for modelling the quirks and flaws of analogue 
technology digitally if they genuinely contribute to the "user 
experience" of a particular piece of kit.  Clearly in the case of a 
Minimoog or tonewheel organ the analogue quirks often get omitted from 
the digital model, and the end-user experience falls short of what's 


On 2019-03-04 21:16, Ben Bradley wrote:
> You're obviously making a little fun of this, but it's remarkable how
> much we use specific things (even specific part numbers for BBDs)
> because of "the sound" they give.
> I had a Minimoog decades ago. I had read an article in Keyboard
> Magazine that the filter input starts to distort if you turn an
> oscillator's mixer level past 8, so I always kept it at 8 rather than
> going to 10. But (what seemed unrelated at the time) I didn't feel I
> was satisfied with the sounds I got out of the thing.
> I've experienced and heard of lots of examples of this, some more
> subtle than others. I recently heard of "real" Hammond player coming
> in to a showroom, playing the modern Hammond/Suzuki keyboards with
> electronically generated tones, and after a couple minutes saying "the
> sound just isn't there" compared to the old Hammonds with the original
> mechanical tonewheel generators.
> On Mon, Mar 4, 2019 at 3:55 PM Richie Burnett
> <rburnett at richieburnett.co.uk> wrote:
>> > From: Ben Bradley
>> >
>> > 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.
>> Or just add some external RAM, then delay the audio digitally and 
>> enjoy
>> lower distortion and a lower noise floor ;-)
>> -Richie.
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