Picturesque 21

Buchla inspired track. This started from exploration of Allen Stranges patch number 21.

Buchla 208 summa summarum

There was only one thing that didn't work as supposed in this build. Sequencer didn't operate correctly in the 3-stage mode (it worked as a 2 step sequence). 4 and 5 step stages worked ok. I changed the 4009 CMOS chip and after that everything worked as supposed!

Complex oscillators coarse slider useful range was only about the first half travel. I made the ModularSynthesis modification and added a 82k series resistor with R45 to reduce the gain of the coarse slider. That fixed this problem.

This build cost me about 2100€. Building was fun and the documentation in ElectricMusicStore, ModularSynthesis, Muff Wiggler and PortaBellabz helped a lot.

Buchla Bongo-box

I made a programming card where random-voltage changes sequencers last step (just one resistor). This way the 5-step sequencer sounds like a longer sequencer and is more interesting. I also switched both lopass-gates serial (signal routing). There is internally a 180-degrees phase-shift between them so when I in the middle of this clip rise the LPG2-level same as the LPG1-level there happens some random phase-cancellations (random voltage opens the LPG2). This sounds like a delay or velocity control. There is no external effect in this clip. Just the internal spring-reverb.

Metaprogramming the Electro Organism

I haven't enough banana cables so it is a good time to test the programming card. In Allen Stranges Buchla Easel manual there is a self-generating patch number 21.

I made a programming that based in this patch. Buchla is in both-mode (prog board + front panel). Random-voltage controls number-of-sequencer-steps, envelope-attack/decay and MO-modulation-mode.Sequencer controls MO-frequency and envelope generator controls lopass-gate1-level. Remaining connections are made with banana-cables. I adjusted the faders to my taste and here is the resulting sound-video.

Buchla calibration

Now Buchla is roughly in tune (1V/Oct) and calibrated. I changed R3 from 10k to 8.2k. This slighty decreases timbre folding and helped the calibration. The trickiest part was to balance the CO-timbre (motherboard TR4) and CO-waveshape (motherboard TR7) with Card9's TR5 (CO low freq track). The problem was to get pure sine-waveshape from bottom to top without any extra oscillations when applying the maximum timbre fold.

I calibrated CO and MO to 1V/Oct with trimmers TR8 and TR9 on motherboard. External CV must be connected to voltage input from keyboard banana-jack. Here is one sound example with long attack/decay times and with random AM-modulation of CO. Some external reverb is used.

Buchla is alive!

It's alive and creating sounds! Next I start to calibrate it. At the same time I check that everything is working. I love the outlook of this thing. It's like a synthesist's candy.

Colors of the sound!

Here in the middle are the calibration trimmers of motherboard.