Hot on the heels of Yamaha's SY85 synth comes the TG500 expander — same AWM2 sound, more sample ROM, and more than double the polyphony of its keyboard sibling. Derek Johnson hails the world's first 64-note polyphonic synth module.

The advances made by synthesizer manufacturers can be measured in a number of ways. Most significantly, there was a time, not long ago, when the closest a musician could get to polyphony was to record monophonic lines onto a multitrack tape recorder and play it back. The next big advance was the polyphonic synth; again it wasn't long ago when 6-note polyphony was the ultimate, but only playing one sound — a pad, for example — at a time. Technology has advanced at amazing speed since those days, so much so that in recent years we have come to expect up to 32-note polyphony coupled with 16-part multi-timbrality — 16 virtual synths within one package — as the norm for a new synth.

This was the case with Yamaha's newest keyboard, the SY85 workstation, reviewed last month. Apart from 30-note polyphony, it featured all the facilities expected from a synth of the '90s: disk drive, sequencer, and sample RAM. Given the undoubted quality of the SY85, I've been looking forward to the module version, the TG500, which we now have under review.

A lot of the excitement surrounding this unit is due to its unique provision of 64-note polyphony — double the previous record. Often hinted at and dreamed of, and as yet unavailable elsewhere, this facility had even your jaded SOS hacks shaking their heads in wonder. And while, as you will read in a moment, there is one slight compromise, for the most part 64 notes is what you get.

Quite apart from 64-note polyphony, there are a number of other ways in which the TG500 is not simply a repackaged SY85. The TG500 features 8MB of second generation Advanced Wave Memory (AWM2) ROM waveforms — that's 2MB more than the SY85 — which contains 294 waves covering acoustic and electric pianos, brass, winds, strings, acoustic and electric guitars, basses, basic synth sounds, choirs, tuned percussion, drums, percussion, sound effects and oscillators. The synth waveforms include generic sounds like pads, synth brass, synth bass and so on; the oscillators include raw sawtooth, sine, and various pulse and digital waveforms. These waveforms are used as the basis for a total of 384 factory presets, including 252 Voices (single waveform patches), four drum Voices (which can be made up of any available waves, not just drum sounds) and 128 Performances — collections of up to four Voices, which can include key and velocity splits, layering and so on. These cannot be overwritten by the user, which brings us to the 192 RAM (user definable) locations, made up of 126 Voices, two drum Voices and 64 Performances; the RAM area also makes room for 16 multi-timbral setups, each of which is 16-part multi-timbral; each part can be either a Voice or a Performance. Initially, the RAM locations (apart from the 16 multis) are loaded with even more high quality sounds.

The TG500 includes the same collection (90 in all) of stereo effects as the SY85; this array of effects actually comes from two internal processors, configurable in serial or parallel configurations.

The TG500 has four individual outputs in addition to the main stereo pair, which the SY85 misses out, and four card slots as opposed to the 85's two. Absent from the standard TG500, however, is on-board sample RAM — though this is available as an upgrade of up to 1 MB. The upgrade consists of two half-meg SYEMB06 boards, which are battery backed up (the samples stay in RAM during power down).

SMALL BUT PERFECTLY FORMED

Appearances can be deceptive, and this is certainly the case with the '500; it is, after all, yet another black 1U rack-mounting box. This is surprising, considering that Yamaha's past serious synth modules (TX802 and TG77) have been packed into 3U boxes. However, anything which saves space and metalwork has to be welcomed. The TG500 has an elegant, if bland, design, and in line with Yamaha's current range of sound modules, from the little General MIDI TG100 to the RM50 percussion module, the front is curved and smooth, with a rather friendly panel layout which is very similar to the RM50's.

Apart from power switch, headphone socket, volume control and backlit liquid crystal display, there are MIDI activity and edit mode LEDs, and a collection of 12 buttons. This doesn't seem to be enough, but clever use of nested software pages mean that no parameter is very far away. These buttons are labelled Play Mode, Edit/Compare, Store/Copy stores, Utility/Select, Page (selects the bits of different editing menus), Memory (selects between different preset and internal Voice and Performance banks), Enter and Edit. There is also a pair of cursor buttons, and parameter/value increment decrement buttons. Last of all are four card slots, two for Voice and Performance storage and two for accessing external waveforms.

Of course there are MIDI connections at the rear, and also audio connections: the aforementioned stereo pair and four individual outputs. These can be freely assigned to voices within Multi-play setups, and individual drum sounds can also be sent to the individual outputs if desired.

In order to reach the holy grail of 64-note polyphony, two 32-note polyphonic synths (or tone generators, in Yamaha speak) labelled A and B are used. This leads to a little bit of fudging later, because if all the sounds in a multi-timbral setup use patches made up entirely from bank A or bank B waves, then you will be limited to 32-note polyphony. This is the compromise alluded to in the introduction, and was probably necessary to allow Yamaha to not only be first with 64-note polyphony, but also to offer it at such an affordable price. In practice, and with care, this is unlikely to cause any major problems.

EDITING SOUNDS

I didn't expect editing on the 500 to be as easy as editing its keyboard sibling; Yamaha have gone for a sleek 1U package for their new module, and accordingly front panel visibility is more limited — no doubt dedicated editors and configurations for generic editor/librarians will soon be with us. The editing hierarchy is logical — but be careful at first. Quick edit facilties are available for both Voices and Performances, where quick tweaks can be done without getting too bogged down in parameters, and this is probably a good place to start if the prospect of serious editing seems initially a little daunting. There are preset envelope and filter types, for example, that allow you to quickly find an approximation of what you're looking for when creating or adapting your own Voices.

A Voice consists of a waveform, followed by an amplitude envelope generator and filter. The EG features five individually programmable rates and two levels, plus rate scaling, which allows the envelope to vary according to pitch; the high notes of a piano, for example, have a much shorter decay than the lower ones.

The filter, as on the SY85, is very comprehensive, with low pass, high pass, band pass, and band elimination options available, plus comprehensive control over bandwidth, resonance and cutoff frequency, and its own envelope generator for comprehensive time-based timbral shifts. On top of all this, there is a pitch EG (envelope), which can add subtle — or none-too-subtle — pitch variations to a Voice, and LFO (with triangle, sawtooth, sine, down sawtooth, square and sample and hold waveforms). Additionally, pitch bend and aftertouch response can be edited, and four MIDI controllers can be assigned to a range of Voice parameters; two other MIDI controllers (one of which would typically be mod wheel) can provide modulation of amplitude modulation depth, pitch modulation depth, frequency modulation depth, EG bias depth and cutoff frequency depth. MIDI controllers can be used for real-time effects parameter changes as well.

PERFORMANCES

As mentioned earlier, Performances are layers of up to four Voices, with various velocity, key zone and effects data. One aspect of editing Performances that is not immediately obvious on the TG500 is the procedures for layer selection and for muting and un-muting layers (there were dedicated buttons for these functions on the SY85). These procedures allow you to de-activate layers, if you wish, and to mute layers while editing. The method for both involves first pressing the Utility/Select button; the display's top line now reads 'PFM LAYER SELECT', and the middle row of buttons — cursor left and right, Page and Memory — are used to select Layers A, B, C and D respectively. The bottom row (Yes, No, Enter and Exit) are used to mute the layers in the same order. This may seem initially inconvenient, but with the limited space available, it's an elegant solution. Just as on the SY85, individual Layers can be edited to a certain extent, with slight envelope or filter tweaks, for example. These don't affect the original Voice, but are part of the Performance.

The final part of any Voice or Performance is the effects, and the reverbs, choruses, flanging, delays and exciters provided here are top notch, with very flexible routing possibilities; some of the 90 effects are mini multi-effects in themselves.

MIDI IMPLEMENTATION

The MIDI implementation is comprehensive, and the TG500 will cope with anything you might choose to send down the datastream, whether it's complex data such as real-time parameter changes, or simply volume and pan information from the mixer page of your sequencer. With so many sounds available, arranged into banks of 64, it may seem a little hard to figure out how you can access them all with program change messages: the simple answer is to customise the program change table, where up 128 Voices, Performances, and even Multis, can be mapped to the whatever program change numbers you like. The more advanced solution is to use a MIDI Bank Select request, which will select the relevant bank before selecting a patch. This is particularly useful when changing patches from within Multis.

HOW DOES IT SOUND?

If you read last month's SY85 review and ran out to your local muso palace to get a demo, you'll know what to expect sound-wise with the TG500. To recap for the rest of you, Yamaha's new sound source is very flexible; rich sounds with lots of inner movement are just as possible as subtle, simple patches. The filters, once again, are a high point of the instrument, and for once polyphony is not going to be compromised when playing 4-Voice Performances. The TG500 allows you to use 16 notes simultaneously in this worst instance, and since its single-oscillator Voices are really rather good, you probably won't be using 4-Voice Performances all the time.

To these ears the TG500 sounds great; raw waveforms do have the occasional too short or buzzy loop, but you rarely find that these intrude on a finished sound, and the actual audio output is very quiet. Hats off to whoever produced the second part of the first demo tune on board: it's actually good music, a William Orbit-type workout amidst the jazz-funk nonsense that are the more familiar on-board synth demos. That said, none of the demos really seems to put the 64-note polyphony to the test.

While I deplore the inclusion of non-erasable presets on any instruments — better a factory bank that you can overwrite and recall at a later date if necessary — the presets provided by Yamaha are uniformly good. For me, the mark of a good synth is finding a sound that is sufficiently musical and diverting to keep me away from the word processor and playing music rather than writing about the instrument. With the SY85, it was a series of piano/pad/string layers. With the TG500, it was a factory Performance called Aster, which consists of a bass sound split with a flute, layered with a mellotron and various sparkly bits. It really was super, and rather inspiring, both musically and by way of making one explore the instrument further. The same goes for a Performance called Mtrix, which is a major, Oberheim-ish polysynth sound that veers between extra mellow at low velocities and woofer-implosion during serious key-bashing. Again, there are so many good sounds that it's hard to single out a few typical examples (but I've tried — see box).

RIGHT ON TARGET

For me, Yamaha's new synths hit the spot; although my decision was made too late to mention it in the conclusion of the SY85 review last month, I have in fact purchased that particular synth. Have I done the right thing, or should I have gone for the TG500? Well, that's hard to say, because the TG500 is in some ways more, and in some ways less, than an SY85. The TG500 offers phenomenal polyphony, even if it is a bit of a cheat, by virtue of the split waveform ROM (this was the case, only more so, with the TG/SY77 and SY99, which had 32-note polyphony on paper, split between AFM and AWM2 sections, rendering them, for practical purposes, 16-note polyphonic).

On the ROM front, the TG500 has the additional 50 waveforms, which means that some of the wonderful new Voices and Performances on the TG500 will not be compatible with my SY85 — I'm working on it, though, trying to find roughly equivalent waveforms. In addition, there are actually more Voices and Performances on the TG500, although the majority are ROM presets. On the down side for the TG is the fact that it comes with no user RAM of its own, and can only be upgraded to 1 MB, albeit of the nonvolatile variety — it seems that due to internal space constraints, the SIMMs memory option which was so attractive on the '85 has been left out. My SY85 will eventually hold 3.5MB, so I feel pretty smug about this. Obviously, the TG500 also lacks a sequencer and disk drive. Should we praise or criticise Yamaha for not providing a simple, straight modularisation of their new synth? Put it this way: I think that if I already owned a keyboard I was happy with, and so didn't need the SY85 at the moment, I would have gone for this module.

Operationally, some may bemoan the lack of a parameter access dial, but a little practice with the increment/decrement buttons gets the job done. Pressing one button while holding the other down results in parameter movements in tens rather than units, so large changes can be made quickly when necessary.

One thing that will take some getting used to is the sheer scope of sounds on offer; even though there is a large number of unchangeable presets, coming to terms with what's available where will take some time. The SY85 has a huge number of patches, all of which are potentially user locations, and when the worst thing you can say about a synth or module is that there too many memories, said synth or module must be good... Remember also that just as there are a lot of sounds on offer, so there are a lot of editable parameters to get lost in.

Potential applications for the TG500 are many: the musician or engineer requiring a lot of sound for relatively little money, whether on the road or in the studio, could certainly do worse than the TG500 — the polyphony and the sonic power go some way to fulfilling the promise of so much MIDI equipment. The sound will suit most people's needs or tastes, since the TG500 is just as capable of working in an imitative fashion as it is of providing airy-fairy ambient noise, producing raw analogue type sub-bass hooliganism, or traditional synth textures.

If Yamaha had just managed to implement 64-note polyphony on an average instrument, it would have been pretty exciting; to find it on a killer module like the TG500 is something else again. I can't recommend the TG500 enough.

Further information

Yamaha TG500 £999 inc VAT.

Yamaha-Kemble Music, (Contact Details).