Science Fair Project Encyclopedia
Casio CZ synthesizers
Casio made programmable synthesizers very affordable in the mid-1980s with their CZ series of Phase distortion synthesizers. There were five models of CZ synthesizers released: the CZ-101, CZ-1000, CZ-3000, CZ-5000, and finally the CZ-1.
The CZ was a remarkably flexible synthesizer, and was cheap enough to make programmable synthesizers affordable enough to be purchased by garage bands. Yamaha soon introduced their own low-cost digital synthesizers, including the DX-21 and DX-100, in light of the success of the CZ series.
Programming the CZ synthesizers
In order to make these synthesizers inexpensive, they did not use traditional analog filters, but were entirely digital. Like many early digital synthesizers, its sound was regarded as "thinner" than the sound of an analog synthesizer.
The CZ line used phase distortion to somewhat simulate an analog filter. It had in total eight different waveforms: as well as the standard sawtooth, square, and pulse waveforms, it had a special double sine waveform, a half-sine waveform, and three waveforms with simulated filter resonance: resonant sawtooth, triangle, and trapezoidal waveforms. The simulated filter resonance was not considered to sound much like real filter resonance, being a simple sine wave at the filter "cutoff" instead of a real filter resonating.
Each digital oscillator could have one or two waveforms. Unlike other synthesizers, where having multiple waveforms added the multiple waveforms together, the CZ synthesizers would play one waveform and then play the other waveform in series; this resulted in there being a fundamental added one octave below the pitch of the sound. It was possible to combine two non-resonant waveforms together, combine a resonant waveform with a non-resonant waveform, but it was not possible to combine two resonant waveforms.
The CZ-101 and CZ-1000 had only eight digital oscillators. Since most patches had two oscillators per voice, this made them four voice synthesizers. The CZ-3000, CZ-5000, and CZ-1 had sixteen digital oscillators, making them eight-voice synthesizers. Each of the oscillators in a two-voice patch could be independently programmed.
The envelope generators in the CZ synthesizers were far more flexible than a traditional four-stage ADSR envelope; they were eight stage envelope generators where each stage had a rate and level value. The rate value determined how fast the envelope would move; the level value would determine what pitch/filter cutoff/volume the envelope would have. There was a single sustain stage, and an end stage.
The synthesizers had but a single LFO , which could only moduate the pitch of all voices in a given patch. The LFO had triangle, square, up ramp sawtooth, and down ramp sawtooth waveforms. The LFO had only three settings: speed, depth, and delay.
The pitch of a voice could also be modulated by a dedicated eight-stage envelope; the envelope generator, alas, could only increase the pitch of a sound.
Each DCF (what Casio called the phase distortion part of the sound which determined how many harmonics a given sound had) was also modulated by a dedicated 8-stage envelope generator. The DCA (which determined how loud a given oscillator was at a given moment) was also modulated by another dedicated 8-stage envelope generator. The DCF and DCA also had a "key follow" feature; which determined how much higher notes affected a sound, making the DCF have a more dull sound with less harmonics with higher notes, and making the DCA envelope faster for higher notes.
It was possible to modulate the two voices in a two-voice patch in two different ways. Ring modulation had the output of one of the oscillators affect the volume of the other oscillator, resulting in a controlled distortion. Noise modulation caused the second voice in a two-voice patch to sound like digital noise, roughly simulating the effect of an analog synthesizer's noise source.
The CZ synthesizers also had the ability to stack up two different sounds via the "tone mix" feature resulting in a functionally monophonic synthesizer; this was Casio's version of the "unison" feature other polyphonic synthesizers had. Each part in a two-patch stack could be a different patch, allowing great flexibility in stacked sounds. It was not possible, alas, to detune the two patches in a tone mix stack; this could be somewhat worked around, however, by giving each of the two patches a different vibrato rate.
The CZ synthesizers did not have some features that analog synthesizers had: it was not possible to modulate the DCF with a LFO; it was not possible to have pulse width modulation; the simulated resonance was an either-or proposition; with the exception of a resonant form, it did not have a triangle wave.
The CZ-101 was the first synthesizer in this line. Coming out in 1984, it was one of the first (if not the first) fully programmable polyphonic synthesizers that was available for under $500.
In order to keep the price low, several compromises were made. The CZ-101 only had 49 keys (4 octaves from C to C) instead of the 61 keys most synthesizers had. Instead of full sized keys, the CZ-101 used miniature keys.
The CZ-1000 was the second fully programmable phase distortion synthesizer that Casio introduced. This synthesizer, introduced in 1985, was identical to the CZ-101 in function, but used full size keys and more attractive membrane buttons. It was also somewhat larger than the CZ-101. Like the CZ-101, this synthesizer had 49 keys.
The CZ-3000 synthesizer used the same phase distortion engine as the CZ-101 and the CZ-1000, but added the following features:
- The synthesizer had eight voices instead of four voices (16 oscillators instead of eight)
- It was possible to split the keyboard (in other words, have some keys play one sound while other keys played another sound).
- The synthesizer had 61 keys, not 49 keys
- There was a built-in chorus effect
- Instead of having just a pitch bend wheel, the CZ-3000 had both a pitch bend wheel and a modulation wheel.
The CZ-5000 synthesizer was almost identical to the CZ-3000, but had more memory for patches, and a built in sequencer. In most other regards, it was virtually identical to the other CZ series synthesizers.
The Casio CZ-1 was the last in the CZ line. This synthesizer, which came out in late 1986, introduced velocity and aftertouch sensitivity to the CZ line of synthesizers. Unlike the CZ-5000, this unit did not have a built in sequencer. The construction of this unit was quite durable and designed to handle touring; it had a metal frame and weighed some 40 pounds. MIDI implementation was also improved.
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