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Casio HZ-600 synthesizer

Looking for a low-cost introduction to synthesis? With its simplified programming method and variant on the Phase Distortion sound, Casio's latest 8-voice, splittable, polysynth could well prove the ideal first choice. Mark Badger explores...

Looking for a low-cost introducion to synthesis? With its simplified programming technique, Casio's latest synthesizer could well prove the ideal choice. Mark Badger explores...

If any company could be said to epitomise the notion of making high technology accessible to as many people as costs will allow, it must surely be Casio. Their reputation for introducing price-breaking electronic equipment is unparalleled by any other Japanese manufacturer. My own first encounters with their marque came back in the early Seventies, when they were producing watches and calculators, a meeting for which I will be eternally grateful. Their calculators made the boring parts of 'O' Level Maths and Physics a breeze, and their watches - with the 'glow-in-the-dark' LEDs and 'timer' functions - were capable of telling me exactly how much longer I would have to endure the tedium of the lessons themselves. It wasn't that Casio were the only people producing such devices, it was that theirs cost about £30 not £300.

Thus forewarned, there must have been a shudder which passed through the collective spines of the Japanese 'pro audio' majors when Casio first announced that, having developed a 'home keyboard' division, they were moving into the synthesizer market.

The appearance of the CZ range certainly gave everyone pause for thought. Using a 'hybrid' of FM synthesis (Casio call it 'Phase Distortion') and 8-stage envelope generators, these machines presented the synthesist with a unique sound and a pretty obtuse programming environment. As anyone who has owned one of these instruments (I still do) can confirm, there are times when you have no idea why adjusting 'the rate of the seventh stage of the digitally controlled wave envelope' has such a dramatic effect on the sound which is attained. But patience, experimentation, and the publication of excellent articles covering just such topics (see 'It's Cee Zee' SOS July/Aug) can be rewarded by achieving some truly excellent sounds.

It has been the strength of these timbres that has forced musicians worldwide to acknowledge the Casio name, and whisper it with the bitter awe which only the person who has spent thousands, and then encounters a machine which'll do the same for hundreds of pounds, can muster.

It was with some anticipation then that I unpacked their latest musical offering, the HZ-600 - an 8-voice polyphonic synthesizer with a full-size, 5-octave keyboard. I mention 'full-size' because its price (£349 inc VAT) puts the HZ-600 into a grey area of the synth market, where such things are open to question and shouldn't be taken for granted. That said, I should add that the HZ-600 is also a 'full-function' synthesizer in virtually every respect, as you will learn in the course of this review.


As with most (all?) Casio synths, the HZ-600 is constructed in grey plastic and, like all the 'budget' models, it can be powered by batteries (six 'D' type) or by mains adaptor (incidentally, never use a power supply from another manufacturer: the Casio units are excellent, reliable, and are fully capable of providing the high levels of current required by the synth, unlike any other unit I've foolishly purchased in the past!).

The full piano-sized keys are, of course, plastic and have a light action with what I can only describe as a "soft bottom" (sexy!), as opposed to the jolt my fingers get when a Yamaha keyboard "hits the deck". These keys trigger the synth with just a small movement, their travel resisted only by gentle springs, and they are thus capable of quite fast licks. The keyboard is not weighted, nor is it velocity-sensitive, as one would expect of a synth in this price range (unfortunately, the HZ-600 doesn't respond to velocity via MIDI either). That said, the keyboard has a pretty nice feel.

The Pitch Bend wheel and Modulation controller add to the pleasure by being quite 'weighty' and responsive, the first being sprung around a centre, the other having a max-to-min range with an accompanying Modulation switch.


The HZ-600 appears to use a refinement of Phase Distortion synthesis (a euphemism for FM to some) which produces a sound with a distinct quality, and which to my ears can be distinguished as 'the Casio sound'. I say this because, as a CZ101 owner, the HZ-600 presets are instantly recognisable, though different. They display the same ability to recreate the 'tchtst-attack' in acoustic sounds as the Phase Distortion system, and share the CZ synths' ability of creating sounds with intense, evolving harmonics. Also, just like the CZs, the presets are pretty awful. At least, as Casio describe them.

The difficulty lies in the way in which the 60 sounds carried by the HZ-600 when it leaves the factory are labelled. I think you'd have to have been seriously 'hitting the bottle' to mistake their idea of a piano, say, for the real thing. If you blind yourself to their pigeon-holing, however, and add just a little ambient effect, the preset timbres are quite capable of precluding any need for adjustment. They tend to have a sound which I associate with Christmas, events which are beautiful but unreal, magical. To whit, I think my favourite of the presets is 'Fantasy' - appropriately labelled, as it is not really an imitative sound.

This is the key to the problem: either Casio's software people are incapable of adjusting the parameters appropriately or there has been a breakdown in communication between Casio's marketing and design teams. I cannot recognise any of the preset sounds which they have labelled as having 'real world' acoustic qualities as such. Vaguely, yes; convincingly, no.


As with most modern synthesizers, the HZ-600 has two areas of patch parameter memory: one which is fixed and the other which can be used to store your own sounds. On the Casio, this user storage is augmented by the provision of one of the new breed of 'credit card' style cartridge memories, as found on the Roland D-50.

Now, 'patch parameters' is a term which dates back to the early days of synthesizers, when a synth was usually a huge panel of sockets, dials, and switches interconnected by short patch leads, and refers to all the settings required to produce a given sound. Back then, reams of paper and careful work were required to note down all the control settings, inevitably meaning that each day's work would produce unique and un-reproducible timbres. Digital electronics (thankfully) has changed all that (but the terms are still current) and the HZ-600's 20 ROM (read-only memory) preset timbres are electronically 'burned' into the internal computer which controls the synthesizer, and cannot be overwritten or replaced. The 'Internal' 20 RAM memories (random access memory) provide the onboard space to store sounds of your own design, performing in mere milliseconds a job which once took hours. Finally, the optional card memory is capable of storing another 120 sounds.

You should note that these figures pertain only to the 'upper keyboard', and there are more memories available for the lower section, but more on this feature later. Out of the box, the Internal memories contain some excellent sounds that are a little more 'racy' than the presets, and which can be recalled at a later date by re-initialising the Internal memory-a job performed by poking the synth with a match-stick or something similar (pretty low-tech, eh?).

Instead of using the LCD display (a rather nice affair) to show the name of each sound, Casio have printed them next to rows of buttons and LEDs on the synth's top panel. Timbres are selected by pressing either a Preset, Internal, or Card button, followed by the 'Upper' or 'Lower' button, then finally the button for the timbre itself is chosen. While this arrangement is fine for the ROM sounds - since they don't change - it, unfortunately, means that the buttons can carry no labels relevant to the RAM sounds, which are liable to be subjected to all sorts of alterations. Interestingly, because the Internal memories have no labels (unless you look in the manual, and who reads them?), I found that I took a more open approach to the sound that they produced, their range and degree of sophistication giving evidence of the HZ's power as a synthesizer.


This power was displayed even more lucidly when I turned to look at the bane of all modern synthesizers, the programming of the earlier mentioned patch parameters and how Casio have dealt with this difficulty.

The problem arises out of the very fact that we have abandoned all those knobs, dials, switches, and patch leads in favour of their digital equivalents. Instead of having it all there in front of us, so to speak, we now rummage around the internal electronics of our synthesizer using only a small LCD display and our ears as guides. The Casio CZ range compounded this difficulty just by having so many parameters, let alone the fact that you have to examine them with a tiny and dim LCD.

It was with some trepidation then that I noticed that Casio have, contrary to the trend of most other manufacturers, opted for an LCD which can display only four characters - 16 fewer than the CZ! I am happy to report, however, that Casio have done an excellent job in overcoming most of the problems associated with display limitations. This is due to a number of factors: the HZ-600 display has much larger characters; they've gone for an 'alpha dial' style of data entry (which involves you spinning a large knob rather than repeatedly pressing a 'data up' or 'data down' button); and, most interestingly, the actual parameters that you can manipulate are fewer in number but have much more significant effects on the timbres that are being produced.

Gone are the 8-stage envelope generators and dual path synthesis of the CZ, though the now standard oscillator, filter, and amplification stages remain. These are now each controlled by simplified ADSR (attack, decay, sustain, release) envelope parameters, all of which have considerable immediate effects on the timbre. Whereas Casio have simplified the envelope controls for timbres, they have complicated the choice of initial waveform by replacing the eight found on the CZ series with a total of 32 on the HZ-600. These range from pure sine to digitised white noise and must serve to perform most of the work which used to be done by the complex envelope generation, as the resulting sounds themselves are still of the 'Casio family'.

The waveforms are selected by, and all other patch parameter editing is done by, pressing the 'Mode' button, spinning the alpha dial to bring the correct parameter up on the display, then pressing the 'Data' button and again spinning the dial to adjust that parameter. It is an easy process to learn and the size of the display ensures that you don't develop the notorious 'Hunchback de Votre Casio' stance associated with most CZ owners.

Another area in which the HZ-600 presents the user with a great deal of friendly operation, is the way it can be split to act as two 4-note polyphonic synthesizers. Pressing just one button accomplishes this usually cryptic task, with the split point instantly displayed by a bright LED above the keyboard. There is a limitation here in that the points are fixed, but there are at least three of them, nicely balanced to provide action to the left or right hand, and I have to applaud Casio's inclusion of a single button dedicated to this function, as well as two dedicated sliders which act as volume controls.

I'll have to carry on clapping as I mention that they've also included a separate set of memory buttons, LEDs, and parameters for the 'lower' voices, albeit diminished in sheer numbers. That is, there are smaller sets of each which relate to the timbres which appear on the lower half of the keyboard when a keyboard 'split' is invoked. Only half the number of Card, Preset, and Internal memories are available (60,10,10 respectively), but these are in addition to those available for the upper part of the keyboard.

This means that you don't edit the top timbre while editing the bottom one and you get an extra 10 RAM memories for your sounds, though here you are limited to a choice of only 16 waveforms on which to base your timbres.

The only other parameters which are not duplicated for the lower sounds are those that control the vibrato effect, where you are limited to sharing it or not, or having its effects delayed for the lower section.

The only let down to my discovery that the HZ-600 is two synths in a single casing, came in the fact that, when split, the two sections both appear on both stereo audio outputs. I had foolishly thought that Casio had thought of everything and that I'd be able to treat each timbre to a distinct effect and mix position, shucks! There is no provision for panning the sounds in the 'Total Control' section of the program parameters either.

What then is 'Total Control'? On the HZ-600, this amounts to being able to set the basic MIDI channel (when split, the lower keyboard section is always set one MIDI channel above the basic channel number), the range of the Pitch Bend wheel (limited to a choice between the intervals of a minor or major third, or a perfect fifth), an overall keyboard transpose function (with a range of a major third below to a diminished fifth above, in semitone steps), chorus (off, 1, 2, or 3), and the memory management functions. Included in these options is a parameter which indicates just how dilatory Casio considers their end-users to be: 'Auto-Off' switches the HZ-600 off after six minutes of continued non-use! This means that you must remember to save an edited sound every time you expect to pause proceedings, or remember to switch the Auto-Off facility off every time you start work, both of which will prove to be a bore in use; at least the CZs have a physical switch for this function.

On the rear panel of the HZ-600 you'll find four quarter-inch jack sockets, the two stereo outputs, and connections for a sustain pedal and foot-controller for the volume level. There is a recessed tuning knob which takes the overall keyboard pitch up or down 50 cents (half a semitone) and a trio of all-important MIDI sockets: In, Out and Thru. Though it will not transmit or receive velocity information, the HZ-600 generates and will recognise MIDI data concerning Patch Change, Pitch Bend, Modulation, and Sustain, ensuring that here is a versatile and economic master keyboard, capable even of receiving and transmitting on two MIDI channels at once! (Though, when this is the case, remember that it will act as two 4-note synths).


All in all, the HZ-600 certainly presents some formidable facilities and I would not hesitate in recommending this keyboard to anyone looking for a powerful synthesizer capable of some pretty stunning sounds, yet who is restricted to the sort of budget which precludes the attractions of velocity sensitivity.

Although there are some silly design mistakes, like both halves of the keyboard split appearing at both outputs, the HZ-600 is basically a sound machine(!). In addition to a decent keyboard and nice controls, it has a user-friendly patch programming environment, meaning it can be easily manipulated to produce custom timbres to taste. There are sufficient synthesis parameters available to allow a very wide variety of timbres to be produced and stored, yet these values have been structured such that you don't end up guessing what is going to happen when you adjust a given control. There is also sufficient memory to enable a fairly substantial library of sounds to be developed. This memory potential can be vastly improved with the memory card. In short, the HZ-600 has all the features required of an introduction to the world of timbre synthesis and electronic music production for the beginner.

As if that wasn't enough, Casio have included a 'split' feature which is easy to invoke and powerful in effect. I would also recommend the HZ-600 to any music professional looking for a distinct sound to add to their armoury of MIDI synths, and one which is capable of cutting through a mix with the sort of lead-line that one normally associates with analogue units. And for those too busy to read manuals, the HZ-600's simplified programming method represents a significant gain in terms of earning potential and immediate accessibility - the less time spent nose-in-text the better!

In fact, I'd recommend the HZ to any musician, but especially to those interested in electronic acoustic synthesis rather than 'real instrument emulation', for it shares its forebears' excellence in the production of enchanting timbres which are distinctly of the Casio ilk. Check it out, at the price you cannot really be disappointed.

Price £349 inc VAT.

Details from Casio dealers or Casio UK, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

The Shape of Things to Come

Next article in this issue

MIDI Matters

Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Oct 1987

Gear in this article:

Synthesizer > Casio > HZ600

Gear Tags:

Digital Synth
Phase Distortion

Review by Mark Badger

Previous article in this issue:

> The Shape of Things to Come

Next article in this issue:

> MIDI Matters

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