OP-1 : Master the dsynth engine

Hi, I open a thread to master the dsynth engine which is a multi envelope dual oscillator synth.

Thanks for your remark/feedback.

1 - Understand the concept of multi envelope :
Envelope crossfader parameter work with decay parameter to define the final envelope for each oscillator.

  • Envelope crossfader parameter define for each oscillator the envelope type in decay section and the envelope amplitude (not envelope volume) → there is no envelope modulation if crossfader parameter is a line (the OSC sound is continuous)
  • Note : grey line is OSC 1 and blue line is OSC 2 (I thought the opposite)

I’ll add pictures when I can …

  • dsynth crossfader parameter :
    OP-1 dsynth crossfader
  • Envelope types corresponding to crossfader “down-up” configuration :

OP-1 dsynth crossfader down

  • Envelope types corresponding to crossfader “up-down” configuration :

OP-1 dsynth crossfader up


ex. below allow to hear OSC 1 alone, then OSC 1 + 2, then OSC 2 alone

OP-1 dsynth envelop 1

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Iinteresting envelope with double attack (echo effect with max value) :

dsynth double attack


Very informative, thank you for shedding some light on this engine!

For the next topic about cross modulation and filter cutoff parameters (graduations in number of notches) :
OP-1 Filter


Summary of multi envelopes concept (for the patch sheet in progress)
Enveloppe recap


This is such a valuable thread, :pray: thanks again!

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I’m really excited to find out if you can shed some light on the mode parameter. Great work so far

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2 - Understand the concept about dual oscillator
(I’m not a specialist. I’m a simple OP-1 explorer)
Before talking about cross modulation, let’s talk about the “frequency” parameter of OSC 2.
The mix of 2 waves with d-synth makes it possible to obtain the analog synthesizer effects.

I don’t know why TE put an M and the values 0,1 because in fact this parameter determines the OSC 2 pitch from 0 to -4 octaves compared to OSC1 pitch.

OP-1 - OSC2 freq

Here are the values that I have chosen to make a playable sound (in notch starting from the octave 0) :

  • 0 - OSC1 and OSC2 are in the same octave : sound clean
  • 1 : sound is bigger + phaser effect → audio link
  • 18 : sub-oscillator effect → audio link
  • 29 - OSC2 is 1 octave lower than OSC1 : sound clean, lower + phaser effect → audio link
  • 37 : sub-oscillator effect → audio link
  • 42 : sound is bigger + phaser effect → audio link
  • 50 - OSC2 is 2 octaves lower than OSC1 : sound clean + light sub-oscillator effect → audio link
  • 55 : sub-oscillator effect → audio link

To try these, use (global) octave shift = -1 with parameter below :

Note : audio examples are without FX.


About filter parameter :

  • from 0 to 36 : low sound (filters high frequencies)
  • 36 : balance point (in my opinion)
  • from 36 to 90 : high sound (filters low frequencies)
  • over 90 : sound becomes inaudible

OP-1 - Filter parameter

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I added audio examples on the audiofanzine site