Casio CZ-101 Review

A review of the Casio CZ-101 synthesizer, from the charitable perspective of someone with experience in ugly, digital noise: An industrial musician.
TL;DR: A novel digital synthesizer capable of creating the kind of beautiful bells and squeaky basses characteristic of 80s digital synths, and not much else. A nice, fun unit if you can pick it up cheaply in good condition. However it compares unfavourably with Yamaha's contemporary FM offerings.

Initial impressions

I won't try to make any imprudent apples-to-oranges comparisons here to contemporary analog or to modern virtual-analog synthesizers. That's certainly not the kind of animal we're dealing with. Casio's CZ-101 is something entirely different. For all its strengths, the CZ-101 is certainly no candidate for "desert island synth". Not unlike an FM synthesizer, it excels in sounds of a particular, characteristically metallic timbre. A trait it shares with most of its digital contemporaries, such as Yamaha's DX series. I was not naive in this regard, having had experience with the afforementioned FM synthesisers. I got more or less what I had expected. Your mileage my vary, caveat emptor.

The initial impressions left on me unboxing the device (lovingly packaged in a handy wooden case for me by its previous owner) were not particularly glowing: Its construction is characteristic of Casio's (perhaps unfair) reputation for cheap, plastic equipment1. The device requires 5 D-size batteries for the retention of patch memory and it has only a single monophonic line-out socket. The keys have a particularly flimsy quality to them, and are not velocity sensitive2. The device has a fairly wide non-backlit LCD screen, which is great by 80s standards.

The editing interface is clean and straightforward, despite its heavy reliance on paging and scrolling. Editing is facilitated by several rows of plastic buttons, which make for a much nicer tactile experience than the Yamaha's DX series' nightmarish signature membrane buttons. For a synth of its kind, patch editing is deceptively straightforward. This synth manages to sidestep the steep learning curve characteristic of Yamaha's FM synths through both creative interface design, and the device's cleverly simplified implementation of Phase Distortion synthesis3.


Diving into the synth engine itself, I was pleasantly surprised by its capabilities. For all it lacks in flair, the synth includes some surprisingly sophisticated features. The ability to control not just the level, but the slope of each segment in the 8-stage oscillator, waveshaper and amplitude envelopes for each timbre was a pleasant surprise. If you paid attention in that last sentence you'd notice that I not only indicated that it has separate 8-stage envelopes for each feature (eight!), but I also said slope. Unlike what has become the de-facto standard in ADSR envelopes, you're not controlling the time of each envelope segment but its slope. This subtle feature caught me by surprise when I was wondering why a value of 48 in the 'rate' field provided a steady, linear increase in volume, while a value of 36 was grindingly slow. I initially suspected there exists some kind of configurable exponential slope to the envelope until consulting the manual. Another unexpectedly nice feature is the ability to control which of the 8 segments functions as the sustain and release segments. This feature, in effect, allows you to use only the number of segments you need in a sound. Very cool.

As mentioned, the CZ-101 uses Phase Distortion synthesis. As a result the synth doesn't have filters. Instead it features waveshapers for each of the synth's two timbres. Phase distortion synthesis functions by modulating the phase angle of a sine wave stored in ROM memory to introduce harmonic changes in the sound. A great, simple explanation of the process can be found here: [4]. One illustative example of this process is increasing the phase angle of the rising edge of the sine wave, while decreasing the phase angle of the falling edge. This distorts a sinusoidal wave into a sawtooth like form. Through this process the CZ-101 is able to construct an array of novel waveforms. The manual provides some insight into this process, complete with useful diagrams. The waveshapers, and their accompanying envelopers, seem to adjust the intensity of this distortion. Higher settings pushing the sine waves much further towards sawtooth waves, increasing the frequency as a consequence. The effect, while entirely foreign in theory, is not too unlike that of a VCF in practice and is able to create familiar sounds with some small effort.

Among its other features are a ring modulator capable of creating seriously harsh tones, and a very flexible key tracking facility for the oscillator, waveshaper and amp sections. One interesting feature is the ability to use either the second timbre to ring modulate the first, or use the first timbre to modulate itself. Aside from its very generous envelopes, the synth offers very little in terms of modulation. However this is standard among 80s digital synths. Apparently, according to this very interesting website: [6] there are some hidden features on the synth accessible only by SysEx. It's certainly worth a look!


Depending on what you're trying to create, it's not hard to spin up interesting sounds from scratch on the CZ-101. Again, tending towards the usual percussive bell sounds common which defined the music of the 80s. The presets are exactly what you'd expect. Ghastly strings, bright brassy saws… And the particularly evocative 'Fairy Tale' patch famously used by Burzum5. For what it's worth, the process of getting a usable patch from scratch is much easier than on an FM synthesizer. It is worth noting, however, that the CZ-101 does not ship with a usable initialised patch in the empty internal storage slots.

The sound of the synthesizer is what you'd expect from a budget digital unit. The output is quite flat and muted. However it's nothing so severe that post-processing with EQ and an exciter can't clean it up nicely. It didn't take long for me to create dark and brooding metallic pads that really pulled me with their striking, harsh tones. The unit is definitely rough around the edges, but without any doubt it's capable of impressive sounds.

So I'm convinced, where do I sign up?

These synths don't appear to be particularly common, nor entirely rare. They've achieved a well-deserved cult status for reasons that this blog post will attest to. The Australian synth market suffers from highly inflated prices, so I can't testify as to their affordability where you may be. I overpaid for the novelty of mine, however I hear that those in theUS are able to pick these things for bargain prices. I found mine on eBay, however they're regular features on Reverb and trading post pages like Gumtree (If you live in Australia like I do). I can't speak for the CZ-3000 and CZ-5000 personally, however all evidence seems to suggest that Casio improved considerably upon the design of the CZ-101 in the later models in the series.


This synth certainly features an engine designed by intelligent, forward thinking engineers who had a genuine, inspired idea to explore. It was seemingly then belted and bashed into a budget unit fit for the hobbyist market7. It's not a good quality instrument by any means, however it's an absolutely great novelty digital synth capable of fantastic, beautiful bell sounds and harsh digital noise.

The CZ-101 is a novel digital synthesizer capable of creating the kind of beautiful bells and squeaky basses characteristic of 80s digital synths. However it doesn't excel at much else. It's a nice, fun unit if you can pick one up for a bargain price in good condition. However the it compares unfavourably with Yamaha's contemporary FM offerings, which are not only capable of more versatile synthesis but are of a much higher quality overall. For not much more of an investment, one could pick up an actual DX7.

If you're a fan of 80s digital like I am, jump on in. This is a fun synth capable of uniquely alien sounds. If you're a beginner to the synth world looking for somewhere to begin, my advice is look elsewhere. A more well-rounded synth can be found more cheaply and easily elsewhere.

  1. They make great calculators and watches, why their reputation for keyboards is so dreadful is beyond me.
  2. This might seem an absolutely unforgivable sin by today's standards. However in 1985 it was a different ecosystem. Also, before you judge too harshly, consider that Korg's Volca FM, a similarly priced hobbyist made over 20 years later, doesn't receive velocity over MIDI.
  3. The CZ-101 provides a preset array of harmonic waveforms created via phase distortion synthesis for the user to use as the basis of their patches. This is in sharp contrast to Yamaha's DX series which required a much more nuanced understanding of FM synthesis to create useful waveforms. A better explanation of nature of PD synthesis and how it differs with FM can be seen at [4].
  4. https://electricdruid.net/phase-distortion-synthesis/
  5. https://youtu.be/cWKtrze79Ys
  6. https://www.kasploosh.com/cz/11800-spelunking/1-which_bits/
  7. https://youtu.be/GPWEnmEYxqs