If you're working to a budget and would dearly love a synth with the initials SY on it, you could well find yourself in the ranks of the thirty somethings...

Yamaha's SY35 is just the latest in a long and prestigious line which began with the legendary DX7. The immediate descendants of that model - the DX21, DX27 and so on - were more affordable, and in that same tradition, the SY35 is to some extent an entry level synthesizer.

However, the considerable flexibility of this new instrument derives from the fact that AWM (Advanced Wave Memory) as well as FM synthesis is on offer, and the amount of AWM memory available is in fact pretty enormous. The SY35 has approximately twice the ROM wave memory of its immediate predecessor, the SY22, including 128 preset AWM and 256 preset FM waveforms, 64 preset voices in ROM, and 64 user-programmable RAM memories. There are 16 programmable Multi memories to store split or layered sounds and 15 preset Multi sounds featuring additional splits, layers, and multiple MIDI channel setups, as well as one setup used purely for an internal demo tune.

Additional sounds can be recalled using MCD64 or MCD32 RAM memory cards (which start at about £50), and each of the SY35's sounds can use two or four elements - one FM and one AWM, or two of each. The two-line LCD display shows a colon between sound number and sound name for two-element sounds (which are 16-note polyphonic) and uses an asterisk for four-element sounds (which are eight-note polyphonic).

The SY35 also features the Dynamic Vector Synthesis (DVS) system already familiar from the SY22 and originated by Sequential Circuits on the Prophet VS. One niggling problem on the early FM synthesizers was always the lack of a conventional envelope-controlled analogue filter, so handy in setting the overall tone of a sound and varying this through the course of a note. Of course, there is an alternative to altering the filter setting during the course of a note - choose two different waveforms with audibly different tones, and fade from one to another as the note progresses. This is exactly how DVS works, the SY35's Vector joystick defining the mix of waveforms and the Dynamic aspect indicating that the mix can be changed during the course of a note.

To hear the effect of DVS, pick a complex sound such as 'Internal 77; Space' and hit the Vector Play button. Once activated, the vector joystick can control either volume or tuning of each sound element. Move the joystick - up and down only for two-element sounds, left and right also for four-element sounds - and you'll hear a crossfade from one element to another. It's possible to record the way the joystick moves during the course of a note: in the Voice Vector Edit Mode you're given a choice of rates at which the joystick's movement is scanned, and simply playing a note and moving the joystick creates a new vector. If you don't like the effect, try another, and when you're happy, go through 'Store Voice' to save the new vector along with the current voice.

Since the dynamic vector always consists of 50 recorded positions, you need to set these to come close together for good definition on short sounds (say at 10ms intervals), or far apart on longer sounds (say at 50ms intervals). It's possible to edit each of the 50 recorded vector positions in terms of volume or pitch individually after recording.

Many, but by no means all, of the SY35's factory sounds use the DVS. There are eight Bank and eight Number buttons which select 64 Internal and 64 Preset sounds, and these are mostly arranged in logical groups. Presets include eight pianos, eight electric pianos, eight brass sounds, eight strings, eight basses, eight wind instruments, eight guitars and eight chorus sounds: the general character of each sound is identified by a two-character prefix, such as AP for acoustic piano, KY for keyboard, WN for wind and so on.

In the Internal voice list, which comprises editable RAM sounds, you'll find eight synth pads, eight synth 'comp' sounds, eight leads, eight organs, four brasses and four strings, eight sound effects, eight spacey 'musical effects', six percussive sounds and two drum kits. On the review model, the final drum kit had been replaced by a rather ordinary electric piano, giving the initial impression that there were no drums on the machine. There are certainly none used in the internal demo, which while it has a very pleasant selection of guitar and string passages, arpeggios and harmonica-like lead lines, doesn't have the impact of some of the demos we've become used to in recent years.

In fact, the drum kit, when you find it, is pretty impressive - apart from straight and processed bass and snare drums and toms, there are plenty of percussion sounds, several voice-based effects, and some pretty hip percussion voices such as fast scratching, metal clangs and so on.

So what are the SY35's sonic strong and weak points? The basic pianos are pretty good, with no noticeable looping or octave transition problems, and the strings are quite decent, with a particularly impressive tremolo ensemble - an effect most synths don't seem to attempt. Basses and woodwinds are good, but some of the guitars such as 'Gypsy' are a little thin, and the rock guitars with added distortion are pretty ordinary. More on the effects later.

Synthy sounds in the Internal section are also reasonable, with a good selection of thick, detuned analogue imitations such as 'Brash' and 'Sand'. Lead line sounds are surprisingly good too, perhaps because they use 'genuine' analogue waveforms such as square and sawtooth waves doubled up in patches such as 'Power' and '2 VCO'.

It's also possible to find sounds more typical of current 'samploid' synthesizers - inevitably rather short orchestral hits, a fairly basic sax, bells and other metallic sounds. Lovers of the bizarre will be pleased to hear that the Sound Effect bank includes wacky presets such as the pitchbending 'Go Up!' and the even more cryptic 'and >?', which, as its name suggests, is pretty indescribable.

Does the SY35 have any real sonic weaknesses? Since it can produce decent analogue chords, some metallic digital stuff, good synth lead lines and weird spacey effects, it would appear the perfect all-round synth keyboard. And that's true to an extent, but the bottom line is that none of these sounds is quite as impressive as on more expensive rivals. Some of the sampled waves are short, there's a certain sterility and lack of movement in many sounds despite the use of DVS, and above all, the effects are not all they could be.

Most modern synths rely on the quality of their effects, and never have quite the same impact when these are turned off. Obviously this can lead to problems if you decide that the sound you're using is wonderful except for the chorus, and then find that it's pretty dull without it. Where the SY35 is concerned, there are no amazing 65-second reverbs to be found and the sixteen basic effects are not editable except in terms of level, which can be limiting. On the other hand it's pleasing to discover that a synth in this price range has any effects at all.

As you'll see from the accompanying list, the range is pretty comprehensive, but there are limitations; if you want distortion followed by echo for a guitar effect for example, you can't have it, and adjusting a delay to work in time with a particular piece of music isn't possible either. Reverbs are of reasonable quality, if a little short, and though generally programmed at fairly low level, you can always increase this on the RAM sounds.

So what else can you do to edit and improve your own sounds? The first major editable parameter for single mode sounds is Configuration and this offers two-element sixteen-note polyphonic playing, or four-element eight-note polyphonic playing. The pitch bend range can be set for each patch, and aftertouch and modulation wheel can be set to amplitude, pitch, or both.

Although detailed editing of envelopes is possible, there's also a quick Attack and Release adjustment display, as well as an unusual and potentially useful Random Element setting. This offers a random selection of waves, levels or detune settings each time the Yes button is pushed, coming up with two or four randomly chosen waves depending on whether the sound being edited is in two-element or four-element mode.

All elements involved in a sound can be edited individually, and of course the most important aspect of each element is which preset wave it uses. Although the AWM waves are, as discussed above, generally fairly decent, the many FM waves are rather thin, and quite unlike the powerful six-operator synthesis of the DX7.

Four- or even two-op synthesis seems to be the order of the day, and the actual editing that can be carried out on FM waves is pretty limited. In fact, the only parameter available apart from envelope control is called Tone, and this simply changes the feedback level of the loop in the FM synthesis algorithm. Generally this will make waves sound brighter and harsher when set to higher levels, but the effect is different for different waves.

It's possible to copy all the parameters of a voice element from one sound to another, as long as AWM parameters are copied to AWM elements and FM to FM; it's also possible to shift the frequency of each element in a voice up or down 12 semitones and alter the volume, pan and velocity sensitivity of each. The keyboard's LFO can control amplitude or pitch modulation using triangle, saw up or down, square or sample and hold (random) settings, and of course, can be introduced either by aftertouch or using the modulation wheel. A delay can be set before the LFO effect is introduced, together with the rate at which the effect then appears, and of course the LFO's speed is programmable.

Editing envelopes is not too difficult - you can stick with the envelope originally programmed for each sound, which is referred to as the Preset Envelope, or switch to Piano, Guitar, Pluck, Brass, String or Organ envelopes. If you need something more specific, go to the User Envelope and you can program a Delay before envelopes begin, an Initial Level, Attack Level and Rate, Decay 1 Level and Rate, Decay 2 Level and Rate, Release Rate and Level Scaling (to determine how the level of the current element changes in different areas of the keyboard).

The Level Scaling display is accompanied by cute little LCD drawings of the 16 available curves - offering sounds louder at the top or bottom of the keyboard, cutting off suddenly towards the middle, or fading gradually in and out around Middle C (C3 - handily marked on the front panel).

Obviously this sort of facility comes into its own in Multi mode, which allows the SY35 to assign 8 different voices to different MIDI channels. Any voices which are assigned to the current MIDI Send channel of the SY35 can also be played from its keyboard - although you also have a Local Off option if you only want the keyboard to control external modules.

Multis can be given an eight-letter name and use any one of the sixteen digital effects with variable depth. Preset, Internal or Card voices can be used in Multis, and the MIDI Receive channel, Volume, Detune (plus or minus 50 cents), high and low note limit, and semitone shift (plus or minus 24) can be set for each voice.

Preset Multis include layered orchestra, layered harpsichord and strings, powerful brass, layered strings and choir, and bass/piano splits all with the same MIDI channel, and multi-MIDI channel splits for pop, rock and jazz composition. Reprogrammable Multis include layered backing pads, spacey multi-layers with names like 'Mikado', 'Prologue' and 'Epilogue', and a bass/synth lead split.

There's also a selection of Utility parameters many of which remain in memory when edited - Master Tune, Master Transpose, Save/Load/Format/Bank Select for memory cards, Voice Initialise, Multi Initialise, Memory Protect, Factory Voice/Multi Restore, and a handy Recall Mode which lets you bring back the last voice or Multi setup as edited in the buffer memory if you forgot to save it - even if you've been playing other setups in the meantime.

MIDI utilities are as expected - Basic Receive and Transmit channels, Local Control, Pitch and Modulation, Aftertouch and Prog Change Send On and Off, System Exclusive Send On/Off for patch dumping, and options for transmitting all or single voices by Sys Ex.

As usual, Yamaha's documentation is excellent, with a 40-page 'Getting Started' manual, a 60-page 'Features' manual and an Edit Reference/Waveform List card included with the synth. Physical features of the instrument hold no surprises - at 7kg it's pleasantly lightweight, the five-octave keyboard is smooth, sprung pitchbend and unsprung modulation wheels pretty standard, rubbery pushbuttons pleasant enough, and back panel provision of MIDI In/Out/Thru, Sustain, Volume, Stereo Out, 12V power, Phones and Card sockets unremarkable. Of course, there are some disadvantages to having a synth powered by an external PSU, but this does help to keep the weight of the keyboard down.

One slightly unexpected feature of the SY35 is what Yamaha refer to as "Overlapping voice selection" and what others refer to as dynamic voice allocation. In other words, currently sounding or held notes will continue to sound when you select a new voice. This was not implemented on Roland keyboards until the JV80, but is standard on Kurzweils and Ensoniqs. Apart from avoiding unpleasant glitches when you change voices during performance, it allows you to hold a drone chord with one sound and change to a new sound to play a melody over the top - quite invaluable. In eight-note Poly mode or in even less polyphonic Multi modes however, voice allocation is not particularly clever, and is perfectly prepared to cut off a held note when you exceed the number of voices currently available.

As should be obvious from the general tone of this review, the SY35 is not the kind of synth which excels in any particular area. But of course, that needn't be a real disadvantage providing the machine does a little of everything. And this is indeed the case. Included are some typical FM effects, some nice analogue-ish pads and leads, some samploid sounds, some digital-ish vector synthesis effects, a reasonable stab at multi-channel MIDI composing facilities, reasonable drums, a good balance between full editing facilities and the simplified systems demanded of an entry level synth.

For a velocity and aftertouch sensitive synth with sensible pitch bend and modulation wheels, which could happily become the centre of a small composing setup, the price is not too distressing either. No doubt the SY35 will sell in very respectable quantities to first-time synthesists or those looking for an inexpensive all-rounder. Don't expect it to set your musical world on fire, but it should give you a great deal of fun...