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Kawai K4

16-Bit Digital Synthesizer

Following on from the success of their extremely popular K1, Kawai have gone upmarket with the 16-bit K4. Tony Wride looks at the company's new flagship synth.

Synthesizer technology has progressed in leaps and bounds over the past few years, with the price-to-capability ratio changing very much in favour of the buyer. During this last year the prime example of offering more than you thought possible for less than you dared hope has been the Kawai K1, and it is not surprising that the instrument won various awards - including Sound On Sound's prestigious 'Synth Of The Year'. The technology that makes the K1 sound so good basically involves the use of stored waveforms in ROM which can be combined/manipulated in various ways to produce complex original sounds, and now that technology has been upgraded to produce Kawai's new flagship synth, the K4. However, despite some quite major improvements, notably the addition of a filter and onboard effects, and the consequently higher price than the K1, at £895 the K4 still represents good value for money.

The sounds that the K4 can produce vary from lush pads to combination and layered sounds, harsh leads to analogue-style swept filter brass, timpani to electro-toms... suffice it to say that the K4 offers a good range of sounds that should keep most users happy for quite sometime.


In keeping with Kawai's, and indeed several other manufacturers', 'designer' styling, the K4 comes in a two-tone finish - black all over with the odd bit of white for keys and lettering. I've often wondered why black is de rigeur for so much hi-tech gear - is it because it doesn't reflect the lights on stage, or is it supposed to represent something dark, sinister and awe-inspiring?

In keeping with current trends, there is the bare minimum of controls on the front panel: two sliders (Volume and Value), a 16x2 backlit LCD set just left of centre, and a collection of 31 switches which allow you access to the voices and editing. The two performance wheels are conventionally located to the left of the keyboard, not above as on the K1.

The keyboard itself is a five octave C-C weighted type, sensitive to Attack and Release Velocity and monophonic Aftertouch. It has quite a nice feel, although inevitably some will find it either too firm or too soft, depending on whether they've been raised on plastic or ivory. By chance, or maybe because of my heavy-handed playing, I found out what Kawai mean by 'weighted' when one of the 'weights' in question — basically a flat lump of metal glued to the underside of each key - ended up on my lap! I soon replaced the weight using some Araldite, but I did wonder whether Kawai should be using a better glue, as I'm sure no-one is going to be impressed if, as well as spending several months' savings on a K4, they have to buy a tube of Araldite to keep re-fixing said weights. However, since this particular K4 had been used and abused by a couple of other magazines' reviewers before I got hold of it, I don't think that this is likely to be a problem for anyone.

The K4 is powered via a separate AC mains adaptor, which presumably saves a good deal on cost and reduces the possibility of mains interference in the audio signal, but which leaves a lot to be desired in terms of security of connection and durability. In fact, the mains adaptor with my review model didn't work at all, no doubt because somebody had dropped it, which for a moment had me on the verge of developing a distinct prejudice against the K4. Fortunately I had a spare adaptor that did the job, and after a few minutes of listening to the K4's sounds my annoyance subsided.

The sounds that emanated from the K4 can best be described as clean and stunning, ranging from a realistic piano to a superb airy voice sound, with an amazing analogue synth (complete with swept filter) somewhere in between. The range of sounds available is quite wide though, as I will discuss later, Kawai have missed a golden opportunity to produce an even more powerful machine for the sake of a few integrated circuit sockets.


The K4 contains 256 high quality waveforms consisting of 96 DC (Digital Cyclic) waveforms and 160 PCM (Pulse Code Modulation) waveforms. As on the K1, these waveforms are referred to by number rather than name in the LCD window, so you may need to look at a separate printed Wave List Table to help make a selection. The DC waveforms include Sine, Sawtooth, Pulse, Square, Triangle, Rectangle, and numerous other tones representing the main harmonic content of various sampled instruments. Kawai actually say that these DC waveforms consist of cyclical PCM sounds which have been analysed and recombined, so that they are easier to process. The 160 PCM waveforms (you could almost call them samples) are split into four groups: Drum and Percussive; Multi; Block; Reverse & Loop. The sound quality of these PCM 'samples' is excellent, due to the K4's internal 16-bit storage (the K1 was 12-bit) - Kawai claim that this gives the K4 'CD quality' sound. Having listened carefully, I would tend to agree with them - unlike the K1, the K4 sounds crystal clear, with no trace of digital noise. This digital noise (sometimes referred to as quantisation noise) is normally most prominent when sounds are played lower down the keyboard, and is often heard as a 'hiss' or 'buzz' which can be very annoying on subtle tones.

The first 43 PCM waveforms are basically drum samples, which apart from the usual single shot sounds include several loops that allow much more realistic cymbals, tambourines, etc to be created. The next 94 waveforms are sampled instrument sounds, including strings, piano, voices, woodwind, guitars and basses. The majority of these are glitch-free looped sounds, although several one shot 'attack' samples are included - some of the loops are really very good, particularly the strings and voices, and I suspect that some are samples of a complete K1 Multi patch!

The remaining 23 PCM waveforms contain Reverse and Loop samples which are useful for effects. Overall, the choice of waveforms is quite large, but I feel that Kawai could perhaps have reduced the number of guitar and bass samples in favour of a few more synthesizer/sampler 'specials', such as vocal stabs.

Now, what about these IC sockets that I mentioned, and Kawai's missed opportunity? Well, all of the waveforms mentioned above are stored in Read Only Memory (ROM) chips. Now imagine what could be done if, instead of soldering these chips onto the circuit board, Kawai had used IC sockets. Has the penny dropped yet? Yes, you've got it in one! You could change the internal ROM waveforms for new sets. Imagine the potential of the K4 if you could have alternative sets of ROM chips! Or perhaps, given suitable software, the owner of a K4 could programme ROM chips with all the sampled sounds that he/she might want [much like the Korg T1/2/3 in fact - Asst Ed]. Somehow I suspect that Kawai may have already thought about this, but I hope they don't frustrate everybody by bringing out a K4 Mk2 in six months time, just after hordes of people (including yours truly if I can beg, borrow or steal the cash) have purchased the current model.

Figure 1. Possible K4 Source configurations.


Having paddled through the waves, I'd better tell you how the K4 goes about building a sound out of them. A Single Patch can be created from up to four Tone Sources playing waveforms, processed by a filter or filters. You can use one of three modes as the basis for a Patch: Normal (two Sources through one filter); Twin (two pairs of Sources through separate filters); Double (four Sources through two filters in series). See Figure 1.

The filters - DCFs (Digitally Controlled Filters) as they are more correctly known - are what make the K4 something a bit different, since having selected your waveform(s) you can change its tone over time - just as on an old analogue synth. The filter even has a Resonance control. Just listening to some of the presets, especially the Single voices 'AnalogSyn' and 'ResoSynth', reminded me of the Roland Jupiter 8 that I will forever curse selling.

Figure 2. K4 Sound Structure.

However the DCFs are not the end - indeed they're hardly the beginning - of this instrument's sound shaping capabilities. To try and understand how the K4 works look at Figure 2, which shows the format of a basic Single Patch in Normal mode. You can see that to the far left you have two Sources (in the form of a Wave, a DCO, and a DCA). The DCO (Digitally Controlled Oscillator) receives information from the keyboard concerning which key is pressed, and outputs the selected waveform at the appropriate pitch. This pitch can be modified by the Bend wheel, Aftertouch, Vibrato etc. The two DCOs are fed through separate DCAs (Digitally Controlled Amplifiers), and there is the facility to amplitude modulate one Source by the other to create complex ring modulation effects.

The DCA is basically the Source volume controller. Each DCA has its own ADSR envelope (complete with a Level parameter to set initial level achieved at the end of the Attack time), the start of which can be delayed by up to 12 seconds. You can modulate the DCA envelope with Keyboard Velocity, Aftertouch Pressure, and Keyboard Scaling, all of which car be made to either increase or decrease the overall level of the envelope. The Attack and Release times can be modulated by key on and key off velocities, and the Attack and Decay times by Keyboard Scaling.

To further control this modulation, you can choose one of eight different Velocity curves as well as eight different Keyboard Scaling curves, and as with all of the modulation mentioned so far, you can use different settings for each DCA. So, if you can imagine having a piano that gets quieter the harder you hit the keys, mixed with a string ensemble that comes in three seconds after you hit the key, you've got some idea of just the start of what's possible.

Moving right in Figure 2 we come to the DCF. Along with the Cutoff and Resonance parameters, this filter has its own ADSR with similar modulation capabilities to those of the DCA. In addition, you can use an LFO to create wah-wah effects. The Delay, Velocity Curve and Keyboard Scaling Curve selected for Source 1 are also used by the DCF.

The last element in a K4 Single Patch is the Effects section, which adds the final touch to a sound - I'll discuss this later.


It is worth noting that although I described using two Sources in creating a Single Patch, the K4 can produce very good results using just one Source, due to the high quality of its waveforms. On the other hand, when you start using four Sources and two DCFs then you really can produce some stunning sounds with a great deal of movement and change in texture. You can, for example, have a piano and guitar duet with a delayed string and vocal pad being added if the keys remain pressed, and that's just on one Patch. Don't forget that you can also add an effect such as reverb with delay to this Single Patch, just to make it even more mind-blowing!

There are a total of 32 Sources in the K4, which means that in the Single play mode on a Normal Patch (two Sources) you can get 16-note polyphony - this is the absolute maximum - and with a Twin or Double Patch (four Sources) you are limited to 8-note polyphony.

The 64 Single Patches contained in the Internal Memory of the K4 are selected via four Bank and 16 Patch Select switches when the unit is in Single play mode - the default at power-up is Single play, and if you are in Multi rather than Single play, the Single play button will put you in the correct mode. Pressing the Edit button puts you in edit mode, and the Patch Select switches now select sections of the Single Patch structure for editing. Full marks to Kawai for providing a very informative manual, which takes you through the process of editing a Patch in a clear, logical manner. A Recall/Compare button is provided so that you can recall the last edit that you carried out, even if it was some weeks ago, and compare the original sound with your modifications.

Pressing the Multi Play button provides you with a choice of 64 Multi Patches selected in a similar manner to Single Play. Each Multi Patch can contain up to eight separate Sections, each of which consist of a Single Patch plus various parameters which define how the sound is controlled or modified by Keyboard Range, Key Velocity, MIDI Channel, Tuning, Transposition, Level, and Output. It is also possible to specify whether each section will be played via MIDI only, or direct from the keyboard, or both. The Drums section of the K4 is separate from the Multi Patches, so you don't need to use one of the eight Sections just for drums. An example of a Multi Patch is shown in Figure 3, where different instrument sounds are played according to MIDI note number and key velocity.

Figure 3. K4 Multi Patch.


There is no way of reserving a number of notes for any Section - voice allocation is completely dynamic on the K4 - so the processor has to sort out incoming notes and assign them in some sort of order of priority. This can obviously have undesirable results if you try and play too many notes at a time. For example, if all eight Sections of a Multi Patch contain Single Patches each made up of four Sources, you would have a limit of 8-note polyphony. Note stealing will inevitably happen if you get too ambitious and have a bassline running on Section 1, monophonic sequences on Sections 2 and 3, a four-note chordal rhythm on Section 4, a leadline on Section 5, and then try and get the Drum section to play 16th note hi-hats with kick drum on the down beat and a snare on beats two and four (each Drum sound uses up two of the available 32 Sources).

If, however, you choose Single Patches which use only two Sources within some of the Sections, then the polyphony can be increased to the maximum of 16 notes. It requires a bit of careful planning to make sure you are not asking the K4 to become a complete band and make the toast as well, but I certainly had great fun running it from my Atari computer once I had learned not to ask too much of it. You can store a further 64 Single, 64 Multi, and 61 Drum Patches on an external DC 16 memory card but, as on the K1, you cannot use External Single Patches as part of Internal Multi Patches, and vice versa.


The K4 has 16 different types of digital effect including reverb, delay, overdrive, chorus, flanging, feedback and various combinations of these. Each effect has three parameters (eg. for reverb; predelay, reverb time, and tone) that enable you to tweak the basic effect to your requirements, and the result can be stored in one of 32 Effect Patch memories. An external memory card can hold a further 32 Effect Patches.

Within a Multi Patch, each Single Patch can be assigned to one of eight Submix channels, which allow you to set pan positions and effects levels for each Section. A single Effects Patch applies globally to a whole Multi Patch, so the individual Sections that have their effects selection turned on will all be treated by the same effect. It's a bit like having an onboard audio mixer and is a welcome inclusion, though only having the two Left and Right output sockets may not be to everybody's liking. The K4R (rack version) offers six separate audio outs in addition to left/right, but does not have any onboard effects. See Figure 4.

Figure 4. K4 Multi Patch showing mixing facilities.


It seems that no synthesizer today can be sold unless it offers built-in drum sounds. The K4 has a Drum Section that includes 61 Drum Patches (mapped to a different note on the keyboard), each of which use two Sources to create some excellent drum sounds. In this context, 'Patch' means a single sound on a single note, and all the Drum Patches are active within the Section at once. You can edit these Patches, and you are not limited to using the dedicated PCM drum samples for the Sources. Each Source has Wave, Decay, Tune and Level parameters. As with the Multi Section, each of the 61 drums can be assigned to any of the eight Submix channels, so it is possible to choose which of the drum sounds will be effected and which won't. The Effect selection is determined by Multi or Single Patch settings. See Figure 5.

Figure 5. K4 Drum Section.

The drums can be played either by pressing the Drum switch and simply triggering them directly from the keyboard, or by MIDI on whichever single channel you specify. I used my sequencer to drive the Drum Section to accompany some of the tunes I'd been creating on the K4, and the results sounded very professional, but problems can arise because the Drum and Synth Sections use the same pool of 32 Sources. If you play too many notes and drum sounds at once, notes are unexpectedly cut short. This raises the question of whether it is a good idea to have a Drum Section which uses part of the synthesizer's sound structure, or whether a separate drum machine is a better bet? In my opinion, whilst the drum sounds of the K4 are all very usable - I couldn't stop playing the timpani and electro toms - I am more interested in buying a synthesizer to produce good synthesizer sounds, and I prefer to use a separate dedicated drum machine. However, if I were to buy a K4 then I wouldn't hesitate to use the odd drum sound during a fill to complement my drum machine.


MIDI can be used for a good deal more than simply driving the K4 in multitimbral operation - you can carry out all the usual Patch dump/load, Memory dump/load, Patch edit functions via the mighty five-pin DIN sockets, so I would guess that the first K4 Editor/Librarian programs will appear pretty quickly, maybe even by the time you read this. A very welcome feature, not found on many similar instruments, is the ability to change the Single Patch selected for an individual Multi Section by sending a program change command on the appropriate MIDI channel, as opposed to only being able to select a whole new Multi Patch. This adds greatly to the K4's attraction for use with a MIDI sequencer.

The System button gives you access to the various MIDI functions: MIDI Transmit and Receive settings; overall Tuning; overall Transpose; Local On/Off; Velocity Switch Point (a global setting for all Multi Patches).


Despite the minor gripes regarding the separate power supply, the 'weighted' keys, the inability to change waveform ROMs, and the Drum Section, I liked - even loved - the Kawai K4 and the sounds that it produces. The factory presets are on the whole very usable, including the Pianos, which are rather weak on the K1. Things get better still when you move into the realms of Multi Patches - some of them are quite breathtaking, and will no doubt feature very heavily on numerous records in the near future. The full multitimbral capability of the K4 will appeal to anyone who uses sequencers in a big way, although the polyphony might prove a little limiting at times. Also separate voice outputs would have been most welcome, but at this price these are small losses compared to the synthesis power on offer.

If you own a K1 already, then the decision of whether to spend the extra money and trade up to a K4 will be a difficult one. However, if you don't have a K1 but are thinking about getting one, then I strongly recommend you listen to the K4 first and then see if you can't raise the extra cash. If you are contemplating buying a Roland LA synth, or even the mighty Korg M1, the filters, multitimbrality, impressive sounds, onboard mixer and effects, ease of programming - and most importantly the price - of the Kawai K4 mean that you simply must hear it.


£895 inc VAT.

Kawai UK Ltd, (Contact Details).


Tone Generator. Digital Multi Spectrum tone generator capable of 16-note polyphony (2 Sources); 8 note polyphony (4 sources); 61 Drum sounds.

Keyboard. 61 key C-C, weighted, attack/release velocity and pressure sensitive.

Waveforms. 256 16-bit PCM and DC Waves.

Voice Structure. Waveforms routed through a DCA (Digital Controlled Amplifier) and DCF (Digital Controlled Filter). Amplitude modulation of one Source by another is possible.

LFOs. Independent LFOs for Vibrato and DCF Modulation.

Envelopes. Up to 6 ADSR time/level envelopes per voice (4 dedicated to DCA, 2 to DCF) with programmable delay, time modulation, keyboard scaling, and velocity (attack/release) control.

Drums. Separate Drum section with 61 sounds. Each drum uses 2 Sources. Multitimbral operation. 8-part.

Sound Storage. (Internal) 64 Single Patches, 64 Multi Patches, 32 Effect Patches, 61 Drum Patches; (External) 64 Single Patches, 64 Multi Patches, 32 Effect Patches, 61 Drum Patches.

Effects. 16 internal effects types, including reverb, delay and overdrive, which can be edited and stored in 32 Effect Patch memories.

Also featuring gear in this article

Kawai K4 & K4R
(MT Dec 89)

Browse category: Synthesiser > Kawai

Previous Article in this issue

Recording Techniques

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A Visit From The Doctor

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 - Jan 1990

Donated & scanned by: Mike Gorman


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Synthesiser > Kawai > K4

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Digital Synth

Review by Tony Wride

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