TONESTAR 8106 // $479

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 than 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'. Click for nearly thrilling examples in the Out to Outs/Interesting Patches pdf, and read more about the 8106 filter here.

  • Premium Quality Analog® pre-patched and fully modular all hardware synth voice
  • 27 knobs, 6 switches, 21 patch points in a daring yet ergonomic 32hp config
  • Eight octave ARP®, Oberheim® and Moog® styled Oscillator, with sub OSC, octave control, waveform mixing, triangle direct to VCA
  • LFO/ADSR modulation of pulse width with dedicated triangle wave for warming/chorusing effects
  • 6db/oct hi-pass filter followed by a recreation of the Roland® IR3109 module
  • Input drive control and variable tracking
  • Classic ADSR/AR Envelope with original 2600 "sustain sink" behavior to keep it movin'
  • Ultra wide-ranging voltage controlled LFO with input speed control
  • Drone: Instant infinite sustain, and Master mode: ADSR controls both filter + amplifier envelope (Juno 106 inspired)
  • FEEDBACK! Harmonic generating/multiplying Oscillator/Filter Feedback loop manipulation
  • White Noise Generator and External Audio Input patching with native tonal blending
  • Legendary 31 year-perfected Through-Hole build quality and supreme sound-COMPARE!
Toolbar/Tonestar8106/SEM Filter/Synthrotek Lunchbox
Must get shirts

Knowledge from circuit designer
Tim Caswell

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.


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)

All Controls and Patch Points (in order of signal flow)
27 pots , 6 switches , 21 jacks
*Represented by symbol on unit
Normalled connections in blue
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.
NOISE – White noise generator output.
LEVEL – Noise attenuator.
FREQ Frequency, or cut-off attenuator
RES – 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.
A – Attack stage control.
D – Decay stage control.
S – Sustain stage control.
R – Release stage control.
HOLD/MASTER – Indefinite/instant sustain, and master mode for ADSR routing switch: fuses VCF envelope with VCA envelope. Center off.
A – Attack stage control
R – Release stage control.
GATE IN – External gate input.
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.