Making Music
  Computer Music Software and Hardware

The core of the instrument is built around eight two-oscillator voices. They follow a fairly simple and standard analogue synth layout of VCO, VCF and VCA, and the bulk of the main panel is taken up with two identical sets of controls for the two oscillators. This makes it easy to adjust and compare the two settings. Much of the uniqueness of the CS-80 came from being able to create two sounds from the two oscillators and combining them, more of which in a moment.

The VCOs can generate square, triangle, sawtooth and sine waves, and the square and triangle waves can be adjusted with a pulse width control which, in turn can be modulated by an LFO. An improvement over the original here is the ability to select six LFO waveforms rather than just a sine wave.

There are high pass and low pass filters each with resonance controls which the signal passes through in series. You can select a 12dB or 24dB filter curve and additional control is possible through a filter envelope with attack, decay and release sliders. The total filter output can be further adjusted with a volume slider as the signal makes its way to the VCA section. This has the four standard controls - Attack, Decay, Sustain, Release - and that essentially concludes the main sound-generation section although there are many additional controls that can radically affect the sound as we'll see.

Neat feet

The pitch of the oscillators is set with Feet sliders, a throwback to the days of organs stops when pitches were determined by the length of the organ pipes. Settings include 16' (one octave below), 8' (normal pitch), 5 1/3' (fifth higher), 4' (octave above), 2 1/3' (octave and a fifth higher) and 2' (two octaves higher).

The 1/3 settings are interesting as they let you play simple intervals which can be used melodically or, depending on the sound the oscillator is generating, to create more complex tones. You can detune the second oscillator to create thicker sounds and there's a mix slider to balance the output of the two oscillators. The sync button synchronises the start of the first oscillator to the second one so you would mainly hear the second oscillator with the first one generating harmonics. You can also direct the second oscillator to the filter and VCA of the first.

There's a Sub Oscillator section which you might imagine adds a tone below the pitch of the main oscillators but it doesn't; it's actually another LFO which can be applied to the VCA, VCF and VCA individually or all at the same time. There is a speed control and a choice of six waveforms.

The Ring Modulator was another major feature of the CS-80. It multiplies the output signal with a sine wave creating additional harmonics, often with a metallic edge. The curiously-named Mod control sets the balance between the dry signal and the ring modulated one while the Speed slider sets the sine wave pitch. There's a Depth control and also Attack and Decay envelope controls. Ring modulation definitely adds an extra dimension to standard analogue synthesis and although the type of sounds it can create are taken for granted today it was not a feature found on all synths back in the 70s.

There are also three effects - tremolo and chorus with speed and depth controls, and stereo delay with speed, depth and mix controls. You can sync the delays to the tempo when running the instrument as a plug-in with a MIDI sequencer. You can further tweak the overall output with brilliance and resonance sliders.

Touchy feely

But we're still not finished with the modulations yet. One of the major attractions of the CS-80 was its controllability, starting with the keyboard which was velocity-sensitive and supported polyphonic aftertouch allowing different amounts of vibrato, for example, to be applied to individual notes. Unlike the original, the CS-80V is, of course, MIDI compatible and will respond to all the controls your keyboard supports. Several Touch Response controls link the keyboard's aftertouch to the Sub Oscillator to control the VCO and VCF and you can create wha and pitch bend effects with it.

A set of Keyboard Control levers link brilliance and level settings to the keyboard pitch, essentially a 'key follow' function which lets higher notes sound brighter and louder, mimicking the response of natural acoustic sounds.

Another major features of the CS-80 was the ribbon controller, a touch strip above the keyboard which changes the pitch of the notes as you run your finger up and down it. Essentially, it's a pitch bend control. In the virtual version we have to be content with using the mouse. You can create Theramin-type sounds with it but you can't do some of the tricks you could do with the hardware such as playing it with two fingers.

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