[sdiy] Using dual BBD chips for higher clock frequency

brianw brianw at audiobanshee.com
Sun Jun 26 19:16:37 CEST 2022

I'm thinking of the vintage classics that so many modern companies are trying to recreate. Guitar pedals mostly, but also rack and built-in effects.

Now that you mention it, though, perhaps the classics always allowed really high clock rates, but the interesting settings were always the longer delays where the sample rate was really low and the frequency response poor.


On Jun 25, 2022, at 12:20 AM, Vladimir Pantelic via Synth-diy <synth-diy at synth-diy.org> wrote:
> exhibit A: Joranalogue Delay 1
> quoting the manual:
> While Delay 1 is normally driven by its own highfrequency (HF) VCO, creating the ‘clock’ signal required to drive the bucket-brigade delay chip, it is possible to use an external signal to override the internal delay time control. Simply plug the signal into the HF input. For the best results, this should be a square wave with a 50 % duty cycle and a voltage swing of at least 0 to +5 V. The recommended frequency range is 20 kHz to 1 MHz. Below this range, longer delay times can be achieved, but the clock will become audible as a high-pitch whine. Frequencies above this range enable extremely short delay times, but with poor audio fidelity. To keep noise and distortion to a minimum, a high-stability clock source is required....
> On Sat, Jun 25, 2022, 07:27 brianw <brianw at audiobanshee.com> wrote:
>> I don't know whether any company ever shipped a BBD-based product that clocked high enough to even get 20 kHz bandwidth, much less 500 kHz. Most BBD products have less than full bandwidth, such that even us old folks can hear the loss.

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