studio electronics tonestar 8106 price : $549.00

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'.

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."

27 knobbed and "shafted" potentiometers
vco: range, pm man, lfo (^), porta, mod (env), triangle*, saw*, square*, sub, tune; noise: level; vcf: freq, res, kbyd, drive, hpf, env, mod (lfo); lfo: amnt (osc), rate; envs: (adsr) attack, decay, sustain, release, (ar) attack, release; vca: feedback (filter/vca), volume
* symbol

6 switches
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

21 jacks
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
vco:
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:
noise - white noise generator output.
level - noise attenuator.

vcf:
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.

lfo:
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

envs:
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.

vca:
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.

vitals
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)