Music Easel Build – Ryan Bocook

About

The music easel was once a rare instrument that I coveted – an instrument that was mysterious, beautiful, elusive and unobtainable. Only existing in single to double digit numbers with a price tag to match. Some DIY circuit boards were developed by a few aspirational people and then finally, full PCB sets and schematics were created and made available for a pretty hefty DIY project. More and more people got involved, adding front panels, better PCB’s with silk screened reference designators, better schematics, more troubleshooting and calibration help. A true community project.

What I have Learned

Don Buchla, Bob Moog and Serge Tcherepnin were all pioneers of the synthesizer in the 1970’s and all had a “modular” approach
Buchla has several differences from Serge and Moog
Buchla uses 1.2V/octave vs 1V/octave
Buchla separates audio signal path from control voltage
Buchla uses banana jack for CV, tini jacks for audio (vs all banana or all 1/4″ jacks on other systems)
Buchla uses 0-10V CV vs 10Vpp or bipolar CV
Buchla uses vactrols (LED and photo resistors in a small package to block out light)
Buchla uses non-standard controller surfaces (the thunder, 222e and 223e key shapes being my favorite design)
the 200 and then the 200e are the flagship modular instruments designed and sold by Buchla
I purchased a 200e system from Buchla around 2009 and even talked to Don on the phone at that time – this was a massive spend for me (and most folks)
The music easel was designed and built in 1973 as a packaged instrument in a suitcase for portability but not many were made (low double digits) and therefore are incredibly rare and expensive.
In 2012 Buchla sold to BEMI and in 2013 they re-released a production version of the Music Easel (I purchased on of the first units but have since sold it). There was some falling out with Don and BEMI but an out of court settlement was made and Buchla USA formed without Don who passed away in 2016
This DIY build actually wasnt too bad because of the build community – panels, boats, PCB’s and rare parts are all very easy to source
If you go slow and take each section of the build one step at a time, it is fairly easy to break down this complex build into very manageable and simple steps. This is often true of most complex problems – breaking the problem down into the most basic and simple blocks possible and re-construct for the final solution
The original schematics are well laid out and easy to follow from the mother board to each of the 12 cards. There are notes on the schematics for expected values when troubleshooting and calibrating
I cross pinned one of the cards – stupid mistake that cost me a ton of time troubleshooting. I learned a ton troubleshooting, but it was a costly error.
There are a ton of cheap oscilloscope options out there now – for what I needed with troubleshooting and calibration I was really happy with the value
Each card serves a specific purpose or set of functions and modularsynthesis.com lays out the functions, issues, calibration, etc
I learned how to program the STM32 controller on the keyboard but it took me a bit to figure out. It sounds simple to flash and the firmware .hex file is already baked for you to flash, but I ran into a few issues. Also, soldering on that surface mounted processor maxed out my soldering skills as there are tons of little legs and I used conventional through hole methods (i.e. not a heat gun).
I am still having issues with the trigger out of the keyboard pulse not strong enough to trigger the 208 but this appears to be a design flaw. A small circuit has been designed to fix this, but I have yet to kludge it on to the board