TONESTAR 2600 is an ARP® 2600-inspired synth voice 31 years in the shaping, pre-patched like Pearlman's prodigy, and fully #OutsToOuts modular, allowing for highpass/bandpass/notch filter tones, and bristling X-mod effects. Connect CV / gate and twist 'n' switch, or pull its tones and voltages apart one 3.5mm cord at a time. 26 knobs, 7 switches, and 21 jacks make for complex and satisfying signal flow, color and collisions. If it gets reedy, route the triangle wave 'round the VCF, and keep it boomin'. See the Outs-to-Outs / Interesting Patches .pdf for a demonstration of awaiting creations.
Knowledge from circuit designer
The VCO is the same affair as the Oscillation, the Boomstar, and the Omega. It's kind of a combination of Arp®,
Oberheim® and Moog® circuits (sort of a greatest hits), time-tested, very stable—very good tracking over a very
large range; certain parts have to be hand selected to achieve that level of exacting performance.
Editors Note: This module is a TONESTAR—its own thing—and not a 2600 clone attempt;
nevertheless, the Tone☆ tugs lovingly at times on the sleeve of the 1970's era classic.
Envelope FYI: The Tonestar Sustain control replicates the behavior of the 2600 and Odyssey: after the initial Decay, it continues to move (sink) very slowly, adding a little extra texture to the sound. It's technically a flaw, but after digging out my Odyssey, it is for sure a desirable "quirk", and the perfect companion to the 4072 filter (which we mistakenly titled a 4075 in the Boomstar Modular line).
Another bit of fun: The LFO is voltage controlled, so you can envelope, LFO, or otherwise modulate both the rate and the depth; the ADSR amount is also voltage controlled, so it can be manipulated by MIDI dynamics, MIDI volume, an LFO, etc. Greg [St. Regis] has decreed that anything must be patchable to anything, so some technically wrong patchings (for example, pulse wave out to ADSR out) may often produce unexpectedly interesting, x-mod/notch filtering—quite pleasing effects.
The Tonestar was Greg's concept, but as I understood it, the goal was a single oscillator, 2600 VCF, pre-patched and yet fully modular classic synth voice, at a specific size, wielding every trick we could cram in. Main use would be as a go-to bassline/lead tool, or a premium quality, entry-level, complete synth module, for root-to-leaf sound design, and multiform analog exploration/expression.