So, basically, the WSG is DONE:
Done with an asterisk. The battery setup is a temporary kludge to be remedied later. One of the pots and all but one of the jacks are not connected; they were included for the modifications I mostly ended up not doing, but I might get around to adding them in at some point. Other than that, DONE and working.
And only six days after I decided to go ahead. I surprised myself.
As for the other thing… I’ve found out more about microcontroller synths in the past few days and I want to summarize here, for my own reference if no one else’s. A number of these are written up at Arduino Playground, with links to resources including open source code libraries, tutorials, and so on.
One of the first I know of is Noah Vawter’s 1-Bit Groove Box dating from early 2006 or so. The schematic shows an Atmel ATmega32P.
Another early one is AVRSYN (archived page), by Jarek Ziembicki. There were (at least) three versions. One was based on the Atmel AT90S8535, the second on the ATMega16, running at 8 MHz; a version of the latter was sold by Laurie Biddulph Elby Designs. Currently they sell a version based on the ATmega32 . Ziembicki made a third version using the ATMega168. Daniel Kruszyna made an ATmega32 version written up here and made his own additions to the software, which is available on his page. (It includes a simulation of the Moog ladder filter, based on this paper.)
James Grahame used the Ziembicki/Biddulph/Kruszyna synths as a starting point and added some new features to create the MeeBlip, also using the ATmega32. It’s an open source hardware and software product.
Matt of HackMe Electronics designed the Rockit, a hybrid synth built around the ATmega644P handling digital oscillator duty; its output is processed by hardware envelope generators and a multimode hardware filter. There’s a “little brother” to the Rockit called the Sprockit. Both are open source hardware and software. The Shruthi from Mutable Instruments takes a similar approach and is also open source.
All of these synths use custom designed hardware, which is as it should be for those who have the hardware design skills. But there have been experiments with using Arduinos as synth engines.
The Auduino was created in 2008, and “davitr0n” built ADASYNTH in 2010. This is the only one of these synths I’ve seen so far that uses patch cords, though details of the project are sketchy. In this photo I see 18 banana jacks, 4 toggle switches, and 8 pots. None of the AVR based synths I know of has move than about 8 knobs and some have much fewer (the Shruthi has 4 pots and a rotary encoder; apparently it also has 4 CV inputs and 2 CV outputs). Of course the AVR chips they’re based on have only 6 or 8 analog inputs so multiplexing would be needed to handle more.
SNAZZYFX sells an “Arduino compatible chipset”-based synthesizer module called ARDCORE; sketches are available to make it function as any of many kinds of module, though it’s not a full synth.
The Arduino Due just came out last year. I don’t know of any synths that use it, but surely they’re on the way. Looks to me like it’s fast enough and powerful enough to challenge and overtake the capabilities of the custom AVR based hardware.