TONESTAR 8106, an ARP® 2600-inspired complete synth voice, infuses Tim Caswell's "Jupiter to Juno" filter alchemy—a 6db/oct hi-pass filter followed by a recreation of the Roland IR3109 module—into our Tonestar 2600 platform; this chirpy yet full-bodied 8106 model is also fully #OutsToOuts modular featuring 27 pots—one more that the 2600 model for the high-pass filter, 6 switches—one less, sacrificing resonance modulation for that high-pass filtering, and 21 jacks. If the Tone☆ 8106 thins somewhat with resonance excess, route the triangle wave 'round the VCF with the "NO VCF" switch setting, and keep this juicy reimagining of the Roland® IR3109 module boomin' and gloomin'. Nearly thrilling Out to Outs/Interesting Patches .pdf (there).
Caswell Knowledge (circuit designer talk):
"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 (initially), 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."
VCO: OCT (up/null/down); FREQ/PW (frequency/null/pulse width); NO VCF (VCF/null/no VCF); VCF:TRIANGLE*/SQUARE* (triangle/null/square); ENVs:HOLD, MSTR (hold/null/master); VCA:IN/MIX * symbol
VCO: TRIANGLE*, SAWTOOTH*, SQUARE*, MIX, 1V/O, MOD IN; NOISE:NOISE (white); LFO:DEPTH, TRIANGLE*, SQUARE*, SPEED; VCF:EXT IN, FIL OUT, MOD IN; ENVs:MOD IN, ADSR OUT, AR OUT, GATE IN; VCA: IN/MIX, VCA IN, OUTPUT * symbol
All Controls—arranged in order of signal flow—and Patch Points
RANGE – Oscillator frequency attenuator. PW MAN – Variable pulse wave width control. OCT – +1/-1 octave switch. LFO (^) – Triangle wave low frequency oscillation to pulse width control. FREQ/PW – Oscillator frequency, or Pulse (square wave) width to ADSR modulation routing switch. Center off. PORTA – Slew generator control. MOD (ENV) – Oscillation modulation via ADSR control. TRIANGLE*/NO VCF – Triangle to VCA switch—bypasses VCF. SAWTOOTH* – Sawtooth wave attenuator. SQUARE* – Square wave attenuator. SUB – Square wave Sub Oscillator attenuator. TRIANGLE* – Waveform output. SAWTOOTH* – Waveform output. SQUARE* – Waveform output. MIX – Composite waveform output. 1V/O – One volt per octave control voltage input. TUNE – Master fine tune (approx. -5/+ 5 semitones). MOD IN – Modulation CV input. Normaled to ADSR; ADSR is replaced when alt. source connected. * symbol
NOISE – White noise generator output. LEVEL – Noise attenuator.
FREQ - Frequency, or cut-off attenuator. RESO – Resonance, or Q attenuator. KYBD – Keyboard/voltage tracking attenuator. DRIVE – Oscillator output to filter input attenuator. HPF – High Pass Filter. ENV – Filter to ADSR envelope attenuator. MOD (LFO) – Filter to LFO attenuator. EXT IN – External audio input. FIL OUT – Filter audio output. MOD IN – Frequency or Resonance modulation CV input.
TRIANGLE/SQUARE* – Waveform select switch (triangle core). AMNT (OSC) – LFO to Oscillator control.
RATE – Speed or rate attenuator. AMNT – Control voltage Input. TRIANGLE* – Triangle wave output. SQUARE*– Square wave output. RATE – Speed or rate CV input. * symbol
A – Attack stage control. D– Decay stage control. S – Sustain stage control. R – Release stage control. HOLD/MSTR – Indefinite/instant sustain; master mode switch for single ADSR: fuses VCF envelope with VCA envelope. Center off. A – VCA Attack stage control R – VCA Release stage control. MOD IN – Allows for dynamic modulation of the ADSR, eg., if you want the amount of modulation added to/determined by a external source, jack in; or if you prefer, modulation input to the ADSR routing—use with velocity, or a sequencer: the sequencer could isolate the ADSR amount the amount to a single step in the phrase for example. Exciting. A second external envelope can provide an interesting effect, or the AR (in the box patching). ADSR OUT – ADSR output. AR OUT – AR Output.
FEEDBACK – Oscillator/filter feedback loop control. VOLUME – Master volume control. VCA CV – Amplifier control voltage output.
IN/MIX – VCA mix input switch switch (normalled jack). When set to IN, external audio replaces filter output to VCA; when set to mix MIX, filter output is fed along with the filter audio to VCA. VCA IN – Audio input. OUTPUT – Main output.
PCB Mounting Scheme - Through-hole. Filter - A 6db/oct hi-pass filter followed by a recreation of the Roland® IR3109 module, which is a 4 pole, 24 db/oct voltage controlled lowpass filter with voltage controlled resonance. 3 dual OTAs with similar topology to the BA662 used in the Jupiter 8 (and the IR3109 module) were employed, 1 amp for the hi-pass filter, 4 (with added buffers) for the low-pass, and 1 for the resonance. This filter takes a wide range of input signals, and tracks control voltage extremely well. Tap points are available for 6db, 12db, and 18db/oct. Although the topology is similar to the 4072, the tonality, especially when over driven, is distinct.
Size - 32hp. Depth - 35mm including connectors. Power Usage - 130mA, 80mA (+12 / -12)