[sdiy] MIDIVerb reverse engineering

[brianw]

Thank you!

I believe that it is very worthwhile to preserve knowledge of vintage electronics design.

I took a quick look at the collection of files, and specifically the schematic. It seems that the "DSP" is actually implemented via discrete logic chips. I also noticed that there is a pipeline which is potentially quite confusing. Do you have a high-level overview of how this "DSP" works?

I recall looking inside my A.R.T. MultiVerb back when it was new, and it also seemed to have discrete "DSP" controlled by a too-slow-for-digital-audio-sample-rates 8-bit MCU. I've long been curious how that worked.

Brian Willoughby


On Jul 16, 2025, at 12:35 PM, Eric Brombaugh wrote:
> Back in 2021 Paul Schreiber and I reverse engineered the MIDIVerb I and although Paul posted a number of Youtube videos to discuss what we'd learned, we decided at that time to keep the design materials we'd generated from that effort private. Now that Paul is no longer with us I've open-sourced the materials on Github:
> 
> https://github.com/emeb/MIDIVerb_RE
> 
> This repository includes schematics, presentation slides, source code for the disassembler, emulator and compiler, as well as SPICE and Verilog models of the logic. Anyone at all curious about how this product democratized the world of algorithmic reverb is invited to take a look - it's a fascinating glimpse into 1980's minimal TTL design and a testament to the genius of Alesis founder Keith Barr.
> 
> Eric