alfa4 Prototype. Done.
I finished the prototype today. I’ll update this post with some more details soon, but for now, here’s a picture of the completed system. I need some sleep! ?
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alfa4 VCADSR #2
The last module for the alfa4 system is the second quad VCADSR. I left it til last because the first one was the hardest module in the system and I needed to mentally prepare for the build! It’s pretty much exactly the same as the first one, so if you want any technical details, please … Read morealfa4 VCADSR #2
alfa4 Poly Controller
Poly what? Yeah, I wasn’t really sure what to call this! In the final version of alfa4 I’m planning to normal lots of the inputs to outputs and there will be some sort of master controller. For the prototype, I haven’t done this as I want to work out what normalisations will be most useful … Read morealfa4 Poly Controller
alfa4 VCA Prototyping pt.2
The pots for the quad VVCA prototype finally arrived from China, so I put it all together. First, I wired up the ground buses and the attenuators, then attached the panel connections. Next, I constructed the stack and connected everything to the boards. Finally, I added the power/mixer board and wired that up with DuPont … Read morealfa4 VCA Prototyping pt.2
Distortion Update
I always seem to be on a quest for more/better distortion! I’ve built a few distortions, but I still wasn’t happy with the situation. The Plague Bearer is killer, but it’s quite a particular sound and not suitable as a “general” distortion. The Antumbra DIST sounds great, but the output volume is far too low. … Read moreDistortion Update
alfa4 VCA Prototyping pt.1
I’m building the alfa4 VCAs using the AS3360 dual VCA chip. I initially planned to use two chips to give me 4 VCAs, but realised I could use the velocity out of the MIDI-CV module to make things more interesting, so decided on 4 chips to give me 4 dual VCAs. I redesigned my panel … Read morealfa4 VCA Prototyping pt.1
[Video] – alfa4 Test Run
Having finally got round to calibrating the oscillators and the MIDI-CV converter properly, I gave alfa4 a little test run with some massively cheesy chord progressions! This is just saw waves from the VCOs going into the quad filter, which is enveloped by the quad VCADSR and modulated by the quad LFO. It’s all going … Read more[Video] – alfa4 Test Run
alfa4 VCADSR Prototyping pt.2
Having verified the circuit works correctly, I set about putting another 3 of them together for the first envelope module. Then I cut and drilled the panel and labelled it up. I designed this at 38hp, but due to the general inaccuracy of my panel fabrication technique, the gap in the case is 39hp, so … Read morealfa4 VCADSR Prototyping pt.2
alfa4 VCADSR Prototyping pt.1
I looked long and hard for an ADSR circuit using the CEM3310/AS3310 which had voltage control over all four envelope stages and found only one, with very little in the way of accompanying documentation. It was this schematic by Dr. James J. Clark, which I came across on the Electro-music forum: I decided to base … Read morealfa4 VCADSR Prototyping pt.1
alfa4 Quad LFO
The last of the modules for the 1U row in alfa4 is a quad LFO. They’re just very simple triangle/square LFOs based on a Thomas Henry circuit design. I used a couple of the same boards previously (acquired from John Miscreant via MW) for the dual LFO in my main system and I like them, … Read morealfa4 Quad LFO