Synth DB

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Spectral Audio | ProTone


The ProTone is a true analog synth from the mid-nineties for the modern MIDI studio. It is monophonic and features two analog oscillators, a beefy resonant filter, flexible LFO, MIDI and CV/Gate control, and a simple intuitive hands-on layout with every control parameter accessible from the front panel knobs and switches.

Each oscillator features saw and pulse waveforms with independent waveform selection, tuning and level. White Noise is also available from VCO1. The oscillators can be sync'd and Ring Modulation can also be dialed in. The filter section allows for either high or low pass filtering and 12 or 24 dB/oct slopes with the usual cutoff and resonance knobs. A fairly standard ADSR envelope can be applied to the voltage-controlled amp, but there's only a decay envelope (Accent) for the filter. The LFO is quite flexible, with six wave shapes plus random, noise or external input. The LFO can be set to modulate VCO1, VCO2, Pulse-Width on VCO1, filter cutoff and panning. A few remaining controls include a Panner, and Slide (portamento) effect.

The ProTone features MIDI I/O and traditional CV/Gate I/O for use with vintage gear. A little too much like vintage gear, however, the Pro Tone does not have on-board program memory. But with such a basic synth architecture and no hidden menus or parameters, the ProTone is a hands-on tweaker's synth - full of fat analog bass and synth sounds with a squelchy filter and competent LFO. Additional features include external VCO and LFO inputs, MIDI controlled volume and frequency cutoff, velocity sensitivity, and stereo outputs. The ProTone makes a cost effective, reliable and unique alternative to many other older vintage dual-VCO analog mono-synths.

BrandSpectral Audio
Engine TypeAnalog
Voices (max)1
LFO1 (Rectangle, Impulse, Triangle, Sawtooth, Sinus, Noise and Random); Wide LFO Range: 0.005 ... 3800 Hz; LFO Targets: VC01, VC02, Pulse Width of VC01, Cutoff and Panorama
Engine Detailed2 analog VCOs (Sawtooth and Pulse Waves); White Noise Generator; True Ring modulator
Filter (VCF)High and Lowpass Filter with Resonance, Selectable 12 or 24 dB per Octave, Accent (Decay Envelope for the Filter)
Envelope (VCA)ADSR
Key typeN/A
Produced:1996 - 2001
Legend: Obvious Y: Yes, N: No, N/A: Not Applicable
VCO Voltage Controlled Oscillator DCO Digital Controlled Oscillator
LFO Low Frequency Oscillator Sub Sub Oscillator
VCF Voltage Controlled Filter VCA Voltage Controlled Amplifier
Velocity As with a piano, the harder you hit a key, the louder the sound, unlike most organs which always produce the same loudness no matter how hard you hit a key. Aftertouch Pressing a key after you activated it. Channel Aftertouch, no matter which key, it will send a Channel message. Poly Aftertouch, sends the pressure per key instead of the whole channel.
Values for OSC, LFO, Filter, Envelope are per voice unless stated otherwise.

Manuals, patches etc.


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