VCO Section

Mercury-4 accurately models the somewhat odd Jupiter-4 oscillator implementation. Its square wave is relatively standard, but the sawtooth has a uniquely "stepped" wave that changes shape across the frequency spectrum, with the waveshape becoming coarser as notes get higher.

Range- Sets the basic pitch range of the oscillator, displayed in traditional organ footage. Note that range is also affected by the position of the three-position Transpose switch to the left of the keyboard.

Sub switch- Adds a square wave one octave beneath the current range selection, useful for adding girth to oscillator tones. We don't know why they made the switch positions backwards.

(LFO) Mod- Adds frequency modulation from the LFO (low-frequency oscillator) section immediately to the left of the VCO.

PW 1•2•3•4 (Pulse Width) Manual/Mod switch

  • Manual- Pulse wave width or "duty-cycle" is fixed (i.e. not modulated) and is set using the four-position PW slide switch.

  • Mod- Pulse width is modulated by the onboard LFO (generally referred to as "PWM"). The modulation depth is set by the four-position PW slide switch, with position 1 being no mod, and position 4 being the deepest mod. Mod rate is defined by the LFO section Rate slider. A unique Jupiter-4 quirk is that the pulse wave mod depths are slightly different depending on which LFO waveform is used (you can hear this by setting the LFO to a very slow setting, or see it with an oscilloscope, if you're super nerdy like us).  

Wave Form knob- Yes, we know "waveform" should really be a single word, but we went for authenticity here.

  • Off- Main oscillator waves make no sound. The Sub oscillator still works in this position; the Off position is also useful when noise or filter resonance are used as sound sources.

  • Ramp- Oscillator produces a ramp wave.

  • Square- Oscillator produces a perfect square wave (well, as "perfect" as analog synthesis can do).

  • Pulse- Oscillator produces a pulse wave with pulse width defined by the aforementioned PW Manual/Mod and four-position PW switches.

Continue to Noise section