H & H SM200 "digital effects unit" repair

[StephenGiles]

https://www.youtube.com/watch?v=_wSHP_hSkmA&t=249s

The testing of 5 x SAD1024 for your delight - a view of the schematic around 4 minutes!

[Mark Hammer]

That much SAD makes me happy.  My only critique is that it's not really "digital".

[Rob Strand]

Notice the filters have an extra RC network in the feedback path.  That's to compensate for the opamp bandwidth.  It can make the HF noise worse.

Geffe, "How to build high-quality filters out of low-quality parts", Electronics, 1976
https://consort3.files.wordpress.com/2022/06/geffe-filter-paper.pdf

There's a full-wave rectifier in there. Looks like some sort of noise gate with the JFET.

[StephenGiles]

That much SAD makes me happy.  My only critique is that it's not really "digital".

My thoughts exactly!

[ElectricDruid]

My only critique is that it's not really "digital".

At least it's a sampling system, so it's close!!

Tom