etasonix TM-3 Gas-Tube Dual Voltage-Controled Oscillator

via this auction
"(taken from Modular Square)
The METASONIX TM-3 is the only voltage-controlled oscillator on the market with an all-tube signal path. It consists of two thyratron tube sawtooth oscillators, which are wired in parallel but may be offset with their individual front-panel tuning controls. Furthermore, soft sync is available, to force oscillator 2 to track with oscillator 1.The waveform produced by the 2D21/5727 thyratrons is unique and distinctive--a very imperfect sawtooth. It's the kind of sound that screams VINTAGE, because the only other instruments that produce it are vintage ones--the Mixtur-Trautonium, the Univox, and some 1950s electronic organs. Furthermore, there is a suboctave circuit, which adds a square wave one octave below oscillator 2. It includes short pulses an octave above, for a distinctive sound. And you can mess with the STABILITY control to get unique effects--because the suboctave divider is made of two neon lamps, and NOT a transistor flip-flop. Except for the CV driver, the TM-3 is all tubes. And unlike most other synthesizer VCOs, the TM-3 is so sensitive that it is easily used for FM sound effects--simply by driving either CV input with a line-level audio signal. Both inputs are DC coupled and highly sensitive. The result is a unique and very extreme form of signal distortion. The TM-3 is a Hz/V VCO, meaning it follows a linear characteristic. Each successive octave requires doubling the control voltage. As shipped, the first octave is swept from 0 volts to 0.25 volts, the next from 0.25 to 0.75 volts, etc. Although not standard to the present modular-synth industry, this scheme simplifies the TM-3's use as a signal processor and avoids the use of an exponential converter circuit, which can drift with temperature or cause other problems. TM-3's CV control is compatible with vintage Korg MS series and Yamaha CS series synthesizers.
tech specs
Output signal max approx 10 v p-p. Capable of approximately three octave range with CV control, 66 Hz to 526 Hz. Center pitch setting with tuning knobs and 0.0v input gives approx. low C (66 Hz). Actual range obtained depends upon individual thyratron tubes installed--about 2 1/2 octaves is typical. May be controlled from any MIDI-CV converter having Hz/V capability, including the Synhouse MIDIJACK II, Philip Rees Little MCV, Kenton Pro-Solo and Pro-2000, and Encore Expressionist. Inputs: two 1/4"" phone jacks for CV or audio (they mix linearly). Output: 1/4"" phone jack, audio, mono, 50k ohm impedance. Power input 10v AC to 12v AC, 50/60 Hz, 1 amp max at idle"