For some time now we have seen the changeover from analog technology to digital. Over the past few years synthesiser manufacturers have developed various digital circuitry for usage in their existing analog keyboards, the production of the hybrid synthesiser now being a standard design with new frontiers being forged in the purely digital field.

In the event of any new advance in technology the initial price paid is usually far above the amount the average consumer can sustain. The Yamaha CE20 uses a digital FM tone generator derived or spun-off from their GS1 and GSII digital keyboards, its price brings digital into the mass market.

The fundamental, and in my opinion the most important, point in synthesis is the tone generator, it is from this raw element that your sound originates. When using ordinary analog tone generation a voltage change is needed to adjust the frequency, the accuracy of the frequency being dependent upon voltage tracking. The analog oscillator produces only one waveshape and this is then processed through shaping circuits. Although this technique allows many varied waveforms to be created, the peaks and troughs of the waveform are irregular, there is a loss of important harmonics and the waveform is never exact. This is a basic form of subtractive synthesis.

With digital generation the waveshape produced is what you wish it to be, the waveshapes are produced by electronic switch enclosures in a predetermined sequence allowing the construction of complex tones from a series of fundamental frequencies. So in theory strong and exact duplication of known waveshapes can be generated to produce a sound that is both accurate and clean. This formation is the basis of additive synthesis.

"Extraordinarily Natural Voices and Outstanding Playability " are Yamaha's claims to fame in their advertising literature concerning the CE20. Let's see if it's true!

The Yamaha CE20 has a 4 octave, C-C double touch keyboard, it is the combination of an eight note polyphonic synthesiser with 6 presets:— Brass, Horn, Organ, E. Piano, Harpsichord and Strings, to this is added a monophonic section consisting of 14 preset tones:- Piccolo, Flute, Oboe, Clarinet, Saxophone, Trumpet I + II, Trombone, Violin, Cello, Contrabass I + II and Electric Bass I + II.

These sections do not operate independently i.e. you cannot play mono + poly together. When switching from flute to horn for example the flute preset will disable. The presets are effected by touch-lite switching with LED's above each switch to confirm operation. The overall tone can be adjusted by a brilliance control allowing a filtering change between mellow and bright.

The controls which add 'life' to the preset voices are those forming the touch response. Each sound is programmed with its own touch response characteristics and these programmes can be disabled by switching the preset switch off: the manual controls will then operate. These manual controls consist of 'Tone Initial', 'Tone After', 'Vibrato After', 'Depth', 'Speed', and 'Delay'. The first two of the preset parameters are sensitivity controls linked with the attack dynamics of the keyboard producing a mixture of VCF intensity and amplitude, the Vibrato After adjusts the amount of vibrato depth effected by the varying pressure on the key. The speed of the vibrato is controlled by the Speed. The other vibrato controls allow independent but simultaneous adjustment of vibrato away from that controlled by the keyboard response.

The remaining controls are total volume and pitch, plus on the left hand keyboard flank there is a slide control, operated by a non-centering or sprung loaded wheel and a feather-like switch with LED to enable operation, controlling the portamento from short to long — the slide works only with the mono voices.

"IT'S A STRANGE SYSTEM BUT WORKS WELL WITH LEGATO PLAYING AND FAST RUNS."

The outputs on the CE20 are Line Out and Headphones and the unit comes with an expression pedal and a sustain pedal. So how does it sound?

Monophonic Voices:— The Piccolo and Flute are great, good soloing voices, crisp and clean. The Piccolo double touch gives a harder tone imitating a push breath, the Flute has a very delicate touch vibrato. The Oboe is very natural but seems to lose its true tone in the higher registers, the Clarinet is warm and rounded and brightens in the higher octaves. Saxophone is a great sound but not what I consider a sax to sound like. Trumpet I is very good; an orchestral trumpet, bright and forceful with the double touch lending brilliance and volume to the tone? Trumpet II is a jazzier tone, more soulful and heavy. The trombone setting works well with the tone brightening and gives a more natural 'oom-pah' when the double touch is used.

Violin is okay but too percussive, the cello, however, sounds much better, in the lower octaves the sound of the bow and the wood seem to follow and the attack is just right. Contrabass I is a lovely bowed effect which also gives a very strong and definite bass sound, Contrabass II is plucked and again, very clean and in the very nicest sense 'wooden'. Finally, Electric Bass I is a warm bass tone whilst Electric Bass II has a much more funky feel to it — both double touch presets add the important boost of amplitude for expression.

Polyphonic Voices:— You will see while changing from one preset to another in this section that the symphonic switch goes on and off, only strings and organ use the ensembling as a major part of the integral tone, you can however use 'symphonic' on whichever voice you wish, both mono and poly apply.

The Brass sounds a little reedy throughout, this is though a very fast percussive brass, the touch response allows a change of tone and volume but the sound does not 'punch' out. The Horn setting is superb. I was delighted with this tone, it is the best synthesised Horn I have heard, full of warmth and roundness, the attack principle is spot on and the Tone Initial gives a breath push to the sound and the Tone After allows exactly the nuance found in the horn family.

The Organ is a strong, percussive sound, rich in harmonics and very full throughout the keyboard range, the touch response giving a good accent to the sound.

I found the Electric Piano much too percussive however, and the decay and sustain of the tone not enough. But the effect is warm and sounds very Rhodish with a tyne bar effect in the harmonics making it quite real.

"I ENJOYED THIS KEYBOARD, IT IS SIMPLE, EASY TO OPERATE AND WELL DESIGNED."

Piano is the most difficult to judge as acoustic and electric pianos are very different and so very personal. The double touch is for pure volume but the sustain pedal does not allow enough sustained release.

The Harpsichord is pleasant enough but does sound rather electronic and a little weak.

With the brilliance control you can achieve most varieties of string tones, again too percussive for me but the sound is strong although the sustain by pedal does not allow enough movement.

Conclusions? I enjoyed this keyboard, it is simple, easy to operate and well designed.

No knowledge of synthesis is needed as the presets voice themselves. The keyboard has a good feel to it, but when holding a chord down in the left hand and triggering the double touch and playing runs or chops with the right hand you do feel some movement through the left hand.

I was surprised by the portamento which only works when you trigger one note whilst holding the previous note for sliding up or having triggered the lower note and releasing the first note played on sliding down — maybe that's why they call it a slide control? It's a strange system but works well with legato playing and fast runs.

My only other criticism is regarding the attack and release — particularly on the poly voices where the CE20 leans heavily towards percussive type tones. An attack control would have increased its capabilities as would the ability to sustain and or release the piano, brass and particularly strings. I felt I was unable to use the polyphonic capabilities of the instrument td full advantage.

Once used to the technique of the double touch you have in the CE20 a clean respectable advance in a preset based synthesiser.

'Is it worth the money'? you ask. Well, 'You get what you pay for' I reply.

RRP £999.00