[sdiy] OBX-a Poly mod

[Michael E Caloroso]

JL Cooper sold a mod that added a CEM3320 4-pole filter to the OB-X.

I have never heard of an OB-Xa mod that adds P5-style polymod.  Frankly it
would be useless unless a new programmable CV for mod depth can be
implemented.

MC

On Thu, Oct 2, 2025 at 3:14 PM ulfur hansson via Synth-diy <
synth-diy at synth-diy.org> wrote:

> hello list,
>
> repairing my old obx-a (again) i am falling in love with this synthesizer
> (again).
>
> i came across this matrix-synth post that features images of an obx-a
> fitted with a mysterious JL-Cooper mod, allowing for prophet-5 style
> poly-mod.
>
> does anyone happen to have any information on the kits design?
>
> ...or if i should end up feeling brave and design a board to achieve
> something similar - any thoughts?
>
> thanks y'all!
> sincerely,
> -úlfur
>
> Sent from outer space
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