DCO - Digitally Controlled Oscillators

The SQ80 provides 3 DCOs (or Digitally Controlled Oscillators) for each voice. In analogue synthesizers of the day the oscillators could produce a few wave forms and had a tendency to drift. For example the ARP 2600 [ A popular analogue synthesizer that I have used in the past] had three Oscillators two of which produced 2 wave forms and one that produced four. The SQ80 can produce 70 different waves plus 5 drum kits on each of its DCOs. SQ80 DCO controls
Like the ARP the three oscillators are a little different. Oscillator 1 and 2 can be combined using the modes page. For the most part however each of the three Oscillators is the same. The parameters on each of the Oscillator Pitch Pages [OSC1, OSC2, and OSC3] are the same. The controls for each are as follows:
OCT= Ranges from -3 to +5. Adjusts the octave the oscillator is in. For example if set to +0 and you played A below middle C the oscillator will produce a wave that is modulating 440 times per second or 440Hz. OCT was set to -2 then the pitch would be 110Hz, +1 would result in a pitch of 880Hz.
SIMI= Ranges from 0 to 11. Adjusts the pitch upwards by its value in semitones (chromatic steps). Setting this value to 7 raises the pitch by a perfect 5th, a value of 4 raises the pitch by a minor 3rd.
FINE= Raises the pitch by a relatively small amount (about 3 cents). A cent is 1/100th of a semitone. Values range from 0 to +31.
Some settings using two DCOs and the controls OCT, SEMI and FINE: Set OCT=+1 and SIMI=+7 on one of the Oscillators, and leave the other alone (values of 0). These values set the first oscillator to the 3nd harmonic of the second. Here is another useful setting; Set one DCO with fine = +1, the other with OCT=-1, SIMI=+11,and FINE=+31 selected. This will produce a . where the sound rises and falls in loudness as the waves interact with each other. WAVE=Lets you select one of the 75 digital multi-sampled 12 bit waves. MOD#1= and MOD#2= these specify which modulators to use in modulating the PITCH of the oscillator. The values are OFF or any one of the 15 modulation sources. MOD#1 and MOD#2 depth. These values range from -63 to + 63 an control the amount by which the selected modulator will modify the pitch of the DCO. If MOD#1 and MOD#2 are set to the same source then the values will be combined [that is if the depth are both set to +63 the total amount of modulation will be 126.]

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