Blog: Virtual CZ Review

Classic phase distortion from Plug-in Boutique      28/10/14

Track made entirely with CZ-101 by Miklo

To be honest I have a had a bitter sweet experience with CZ's over the years. The CZ-101 isn't exactly built like a tank and unfortunately mine didn't go the distance and it went to silicon heaven in 1992.

In fairness to it I was operating it in very harsh conditions. Hot, dry, dusty and on a country mains supply that would vary wildly between 230 and 270 volts. That in itself would cause the tuning to go off to some crazy other place and when I gigged with it, it was only the fact that I could also run it from batteries that saved my bacon. Quite a nice feature in retrospect.

I would also own a CZ-5000 however that also suffered a similar fate. The CZ-101 also represented my first attempt at emulating patches from more expensive machines. At one stage I had all of its patch memories full of different Jupiter-8 type string sounds until I eventually programmed one I liked. It's not a Jupiter-8 by any stretch but with work and some acquired knowledge it can make some quite impressive analog sounding noises, no question.

Phase Distortion

Now I said before that PD is similar in many respects to FM. However the designers at Casio made a genuine attempt to try and appeal to people long familiar with analog subtractive synthesis. The staggering popularity of Yamaha's DX machines belied the fact that most people understood what was happening with respect to perhaps one or two FM operators but beyond that things got awfully difficult to 'auralise' (is that even a word!!) the output of each stage of its signal path. The key thing with FM was that it was all about frequency ratios between each operator so for those instinctively used to reaching for say the cut-off on a filter this was a difficult concept complicated by and large by the DX's interface.

Changing a single frequency ratio in FM as one operator affects another can have quite unexpected results. Given the mathematically similar concepts associated with PD then, Casio took a different approach by laying out an architecture that was somewhat familiar in terms of an oscillator, something that kind of looks like a filter, which it actually isn't, and finally an amplifier at the end of the chain. Then have two of these chains or 'lines' as Casio called them for good measure. Lines can be combined and detuned in various ways and the pitch envelope with some clever editing can replicate very subtle changes in pitch including an attempt to simulate analog oscillator 'drift' if that's your thing. It was pretty versatile.

So essentially what they were aiming for is an architecture that was reasonably familiar while trying to hide away some of the 'scary' technology in the way that the DX doesn't. The oscillator section on a CZ machine is pretty straightforward in that once a waveshape was selected it was pretty easy to get to grips with the envelope that controlled its pitch, even with 8 stages. Because a CZ doesn't have a filter there is also the question of resonance. This is simulated by selecting any of the resonant waveforms (6,7 or 8) in the first instance, the limitation being that resonance occurs at a fixed value rather than dynamically in a filter you might be more familiar with.

The DCW Envelope, while not a filter, produces similar outputs that a filter would and graphically Casio laid it out where you would expect it to be. And it's in the DCW ENV where PD really comes into it's own. In essence PD is about modulating, or changing over time, the rate of change of the phase or reading angle as it describes the output waveform, this happens in the DCO. And if you are not satisfied with that explanation then you can always try Casio's own patent abstract:

"An electronic musical instrument includes circuitry for modifying an ordinary address signal which changes at a uniform rate over one cycle of a waveform, into a modified address signal whose rate varies in one cycle of the waveform by the use of a modification signal. The modified address signal accesses a storage device such as a ROM in which waveform data is stored, thereby producing the modified waveform data from the storage device. The modification signal is obtained from the ordinary address signal through a predetermined logic circuit."- try explaining that to someone after five pints and a kebab.

Essentially what the DCW ENV does then is alter the amount of this reading angle at any moment in time using it's envelope. It is this control over the amount of phase angle distortion that controls the harmonic content. This concept can be an unfamiliar one but once to you start playing around with say the first two level and rate stages of the envelope it becomes pretty clear what it's doing. Even attempting to do those classic filter sweeps is pretty straightforward with this system. But where it does have the advantage over FM is that one tiny change doesn't upset the apple cart like FM can do, changing the DCW envelope for example affects nothing about what you have done with the oscillators or their pitch envelopes, which again Casio were aiming for in terms of people used to programming analog machines. In a simple statement the difference between PD and FM is that PD operates in the time domain whereas FM operates in the, you guessed it, the frequency domain, all in all making PD a much more manageable and easier to understand solution.

So let's get back to Virtual CZ. One of the really nice things I always appreciate about software instruments that directly emulate specific hardware is when it also has a crack at Sysex integration, i.e. when that software also goes to some length to integrate with the hardware if you have it. For those instruments that fall into this category it greatly increases the appeal.

Virtual CZ will work as an editor and librarian across the CZ range from the CZ-101 right through to the CZ-1 and pretty much everything in between. Now sadly I no longer own any CZ hardware, however I am aware of one caveat here. Adjusting a control on Virtual CZ will not immediately alter the corresponding parameter on the hardware and to be fair it doesn't need to, however once you have a patch reasonably worked up the 'Send Sysex' function will deliver it to your synth. All in all that's a really nice feature.

I can see secondhand prices on these instruments escalating as we speak. This feature is quite unique in software instrument circles, I remember NI's FM7 and FM8 not having this ability much to my disappointment. On the reverse journey Virtual CZ does pretty much what NI's instruments did with respect to being able to also import Sysex. you still need to have your hardware dump that system exclusive in some manner but once on the file system, away you go. So this is a key and unique feature of Virtual CZ with it's ability to integrate in both directions with your hardware if you are lucky enough to have it.

Another really pleasing thing to see is sensible decisions around the UI. Remember this is not an analog synth with lots of knobs in fixed and familiar positions. This represents a synth from the mid 80's characterised by having 90% or more of it's functionality hidden behind multi-function buttons, hierarchical menu systems and a small LCD display.

The easy way out would simply be to replicate that view however Virtual CZ addresses the key desire we all had with instruments of this type, to make all the controls visible and at our finger tips. The danger is of course that this can lead to more 'clutter' however the designers have done a sterling job here while preserving Casio's original design philosophy in terms of appealing to the subtractive crowd while implementing their own synthesis method. The UI is clean, it's well laid out and it is immediately accessible, and it lends itself well to a better understanding of what the synth actually does in terms of PD. Full marks here on the UI. Another nice feature can be found in the bottom right hand corner. For those daunted by multi-stage envelopes you can switch to a much more familiar ADSR view. This is great because a lot of CZ patches don't actually use the full complement of 8 envelope stages and it again it aligns well with more fundamental understandings of synthesis.

So what does it sound like? Well straight up the developers say in their User Manual that they have not had 'insider' access to Casio's specific firmware and offer a caveat in that in some cases some very slight tinkering of parameters might be needed to accurately replicate some hardware patches. Now to be honest that is a fair statement particularly when you consider that we have also seen instruments made by the SAME manufacturer in both hardware and software and even then, there are patches that sound slightly different between the two. Regardless of the never ending purists debate on this subject, the key thing for me however is the ability of the instrument to capture the essence of the machine and it's architecture. Does Virtual CZ do this? Absolutely it does and then some.

It's also worth noting some of the differences and the additional features on offer and some of these add significant value. Unison mode including stereo spread, ADSR envelopes as I mentioned, a base DCW 'amount' control that can be used like a filter cut-off, a lot more polyphony, micro-tonal tuning which you will find in its own view, and the lifting of waveshape combination restrictions to name a few. What VirtualCZ does not have are performance features that specific CZ models possessed such as splits, CZ-1 operation memories and glide on the higher end models.

Aside from an impressive and large enough collection of custom presets to keep you busy I loaded my old factory Sysex from my long defunct CZ-101. To be truthful when I bought my CZ-101 I wasn't exactly blown away by the factory sounds, in fact I programmed all my own.

So ironically enough when Virtual CZ presented those sounds to me again years later I grinned from ear to ear. As woeful as some of those factory patches were, not all of them mind you though, Virtual CZ has nailed them perfectly in all of their 'glory'. A typical trick with digital or single oscillator synths was to add some chorus. For my CZ-101 I used a Boss CE-2 and a Boss GE-7.

Most CZ models didn't have this onboard so for Virtual CZ to have implemented a chorus universally is a godsend. It really takes these sounds to another place and you will appreciate that if you are loading in the old factory patches.

So down to the verdict. I have read a few forums that suggest a few little niggles, stupid stuff like the envelopes aren't as 'punchy' or 'snappy' as the original hardware and so on. I disregard a lot of that stuff because it becomes a little irrelevant in your final mix.

The key point however, as I mentioned previously, is that Virtual CZ captures the essence of a Casio CZ honestly without pretending to be anything else. It takes Casio's vision of making esoteric PD / FM appealing to the subtractive masses that one step further. If you can program an analog synth, you can program this synth no problem. On a deeply personal note I am a little annoyed at the developers.

They have done such a good job they might just kick-start a renewed interest in CZ hardware making that a bit more expensive and harder for me to come by now.

You can get VirtualCZ here at Plugin Boutique ( and the Developers page here at

Lagrange Audio is a part-time blogger, suburban muso, beta-tester and IT Consultant when time permits. He writes about things other people don't


Even more news...


More Videos

Sonic LAB: Bitwig Studio 3 Update - Presentation 

Yeah, that Grid...

Massive X Is Out! We Take A Look 

Native Instruments new super synth

Sonic LAB: Novation Summit - 16 Voice Bi-Timbral Poly 

Two Peaks and some

Sonic LAB: Delta CEP A Paraphonic Modular Review 

Desktop DSP action from Radikal Technologies