Modcan - FMVDO

The FMVDO is a digital oscillator module with manifold possibilities, very accurate tracking and a wide frequency range. In 12HP it combines features of different digital synthesis methods. The main feature is frequency modulation (FM) with two operators which are not limited to sine waves but offer wavetables for instance and allow for generating sounds with complex timbres. In addition there´s amplitude modulation as well.

Unlike analog oscillators that need an external modulator like a LFO or another VCO the FMVDO has an internal phase locked sine wave modulator. This phase locking to the carrier oscillator´s phase produces beat-free timbres that retain spectral relationships over the whole frequency range. The FM index function controls the modulation depth from 0% to 314% while the ratio tunes the modulator to 32 special integral frequencies that are relative to the carrier´s frequency. These features make a very stable FM possible. The ratio can be switched to non-integer frequencies though, for producing inharmonic periodic sounds.

Besides the basic waves sine, triangle, sawtooth and pulse with PWM the carrier oscillator also has a dual pulse with PWM, staircase random with controllable interpolation and finally 10 sample based wavetables. The frequency can be set coarse and fine with two controls.

• voltage controlled parameters: FM index, ratio, wave form selection, PWM/AM
• frequency range of 18 octaves: Low: 0.040Hz-40Hz and High: 10Hz-10kHz.
• Output: /-5V or 10Vpk-pk at 1Kohms
• Input CV 0-10V at 100Kohms
• crystal tuning stability of /-0.005% tracking accuracy over 18 octaves
• 32-bit NCO - 50 micro-Hertz resolution (no zippering)
• 32-bit pseudorandom noise generator - no repetition in 119 hours at lowest frequency
• 90° phase shifted quadrature secondary output
• 1V/oct input with chromatic quantization (switchable)
• audio and LFO range (switchable)