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Yamaha TG55

Tone Generator

The recent launch of Yamaha's new flagship synth, the SY77, seems to have somewhat eclipsed the arrival of its sibling, the TG55 tone generator. Rightly or wrongly, the TG55 has taken something of a backseat whilst its big brother hogs most of the limelight. David Hughes assesses its star potential.

At first sight the TG55 seems to be another in the long line of sample playback modules, following on in the tradition of the Roland U110, Korg M1R/M3R, and the Emu Proteus. For those readers who were hoping for a rack-mounted version of the SY77, I'm sorry to disappoint but you'll just have to sit back and wait - the TG55 isn't it! Basically, the TG55 is the AWM2 sample playback section of the SY77 in a different box.

Physically, the TG55 is 1U high, 19" wide, and weighs in at a healthy 9lbs. The overall construction is just what we've come to expect from Yamaha's professional division, quite rugged and well engineered. The front panel is well populated for a module of this type and there isn't much free space left over. Other modules look quite barren in comparison. The most prominent features on the front panel are the two card slots, one for waveform data and another for voice data. Sadly, neither of these slots feature the essential 'catflap' mechanism: the small sprung trapdoor which protects the interior of the module from the general muck and grime that is a feature of everyday life - especially if you're gigging.

Interaction with the user takes place through a standard two-line backlit LCD 'window', which is just about up to the job. But in view of some of the parameters available, programming the TG55 is a bit like trying to wallpaper the hallway through the letterbox! Also, the display contrast cannot be changed from the front panel, which is a shame because I found the display difficult to read unless I was actually standing right over it.

The remainder of the front panel is given over to a collection of pushbuttons, 12 in all. There are also rotary controls for data entry and volume, a headphone jack socket, and the power on/off switch. The pushbuttons are very slightly concave and don't require too much physical pressure to operate.

The rear of the TG55 is fairly spartan in comparison. It sports a grand total of four audio output jacks, organised as left and right stereo/mono plus two individual outputs, alongside the usual MIDI In, Out and Thru sockets.


Playing the TG55 is simply a case of connecting a suitable MIDI controller (keyboard, wind synth, sequencer etc) and an amplifier. The sound source within the TG55 is a single dedicated microcomputer whose sole function in life is to churn out an endless series of numbers which represent a collection of musical sounds using the aforementioned Advanced Wave Modulation 2 (AWM2). AWM2 is Yamaha's second generation of this waveform storage and reproduction technique. The first generation of AWM was used extensively in Yamaha's Clavinova series of instruments. In more common parlance, the usual term for such a technique is 'multisampling', and this is used to avoid the dreaded 'munchkin' effect which occurs when you attempt to pitch shift a sampled sound higher than, say, two octaves.

The sounds have been sampled at rates of 32 and 48kHz; the internal processing is 24-bit; and the stream of digital data is finally transformed into actual sound waves via a 22-bit digital-to-analogue convertor (DAC). What this techno-speak means is that the sampled sounds are all very clean and noise-free, with a sparkling degree of realism. The TG55 contains two megabytes (ie. one megaword) of sampled waveform data in its memory. In comparison, the Emu Proteus and the Korg M1R both boast a healthy four megabytes.

The factory voices that come with the machine are, on the whole, highly musical and genuinely useful. There are the usual pianos, brass (both acoustic and synthetic) and string presets which seem to be the essential fodder of the preset programmer these days, as well as some highly original synthetic sounds which do a lot more to display the true potential of the TG55. A couple of the voices stand out as being well above par and are definitely worth a listen. Apart from a fairly noticeable transition between two of the multisamples, the 'Piano' (preset 01) stands out head and shoulders above the rest. It's just about the best reproduction of a grand piano that these ears have ever heard, bettered only by a Kurzweil 250! To a lesser extent, 'Warm Organ' (preset 20) is a good reproduction of an old Hammond organ, complete with key click. The same applies to the 'Flute' preset (26) - lots of breath and natural vibrato.

"The filter section is excellent and imparts considerable strength to the machine, rather than existing merely as an afterthought."

Delving deeper into the parameters, the TG55 does appear to offer more for the synth purist than other machines of this type. The structure of each 'voice' is based around what Yamaha call an element, although, again, 'sample' is the more usual term. A voice can use either one, two or four elements as the basis for a sound, and each element has associated with it a low frequency oscillator, two digital filters, three envelope generators, and an effects section! Consequently, there is quite a bit more to get to grips with than might be expected in a mere sample playback machine.

Regarding the samples themselves, I felt that they displayed a certain lack of originality on the part of the designers. There were rather too many electric piano type sounds and not nearly enough variety in the waveforms themselves. Besides the over-abundance of piano sounds, there were the usual mixture of saxes, flutes, horns and the like, some nice breath/vocal type sounds, and some interesting samples possibly derived from additive synthesis techniques. On the down side, I also felt that too much space, about a quarter of the 74 multisamples available, was given over to percussion samples.

However, to add spice to the sonic potential of the TG55, each voice sports not one but two digital filters, each with its own resonance control and associated modulation envelope. It's nice to see the reappearance of the good old filter. Just like flared trousers, I knew they would come back into fashion one day!

Polyphony is an important factor these days. On the TG55, the maximum number of notes that you can play at any one time is defined by the complexity of the voice structure: as the number of elements in a voice increases, so the number of notes that you can play decreases. The TG55 can play a maximum of 16 notes for a voice with only one single element, eight notes for a voice with two elements, and so on. This is a bit of a limitation, I feel, especially in view of the fact that there isn't a MIDI Overflow facility, which has to be seen as something of a serious omission. I was also somewhat surprised by the small number of RAM locations set aside for user programs. There are only 64 such locations available to the user and, in view of how ridiculously cheap memory has become in the past few years, this does appear somewhat meagre.


When you consider the limitations of the average LCD, it isn't hard to see why most musicians shy away from creating their own sounds and simply go for the easier option of the preset voices. Alas, the TG55 also falls into this category, which is a real shame because it allows the performer considerable power and flexibility in terms of what can be accomplished with such a basic system. This situation isn't helped by the fact that the TG55 has a clumsy and poorly designed user interface.

For example, to the right of the on/off switch are four pushbuttons marked 'Voice', 'Multi', 'Demo' and 'Utility'. The TG55 can be played in one of two modes: Voice or Multi. Voice mode allows the user to play a single voice at any one instant and Multi mode allows access to the multitimbral facilities within the machine. You can only ever be in one of these modes at any instant, so why provide two buttons? Similarly, there are two buttons marked 'Enter' and 'Exit', where one single button would suffice. To really hammer the point home, I can't understand why Yamaha have dedicated a single button to the demo function, when it would have been much better to hide the demo play facility within the machine, as it is on other instruments. After all, how often are you going to listen to the demo songs?

"...the sampled sounds are all very clean and noise-free, with a sparkling degree of realism."

The edit facility itself is loosely based around a series of pages with suitably descriptive titles, such as 'filter', 'effects' and 'controller'. I say 'loosely', because this aspect of the software hasn't been implemented in a very sensible manner either. For instance, rather than group all of the amplitude envelope generator variables under an edit page simply titled 'amplitude envelope' - which would seem to be the obvious thing to do — the relevant parameters are scattered around in the 'top level' amongst many apparently unrelated parameters such as oscillator mode, pitch envelope generator, and LFO parameters. The consequence of this is that you tend to spend quite some time wandering around the top level searching for the relevant parameter field.

A better approach would be to extend the 'page' concept to all of the various subsystems within the TG55. It would also be highly beneficial to the user to assign separate buttons to, say, the MIDI management parameters and controller details, rather than to group them under the collective 'utilities' section. Taking a more positive approach, if you persevere and get to grips with this system, many of the terms involved in the edit process will already be familiar to those who have journeyed into the inner workings of the DX7 or any of its close relatives.

There are a few features which deserve special attention. Firstly, there's a fairly comprehensive low frequency oscillator (LFO) section, one of which can be assigned to each element. Along with the standard LFO parameters - such as choice of modulating waveform, depth of modulation, etc - there's a new parameter governing the 'phase' of the LFO waveform. "The change can be subtle," explains the manual. "Experimentation is the best way to find the best setting." Sound advice indeed...

The TG55's envelope generators are of the rate/level type, which are not really my cup of tea. I much prefer the less sophisticated ADSR type, which may not be as flexible but are simpler to use in concept and in practice.

The filters deserve special attention. I was brought up with the old analogue type of filter, that is a hardwired electronic circuit complete with resistors, capacitors and the like. The filters on the TG55 are actually digital simulations of filter circuits, which gives you some impression of the amount of work those internal microcomputers must be performing! They are very flexible in operation. Filter one can be switched to produce either a high pass or a low pass response, whilst the response of filter two is restricted to low pass only. This approach encourages much experimentation with sound colouration. You can combine a high pass and a low pass filter to obtain a band pass filter, and furthermore combine two low pass filters to effectively double the filter slope and produce the classic deep swept filter sound. Both filters have a resonance parameter (although this is only available when the filter is in low pass mode) which can be increased up to the point where the filter will start to oscillate.


The TG55 features 34 built-in effects configurations and these range from the usual reverb treatments through some highly effective chorus and delay effects to some wonderfully way-over-the-top distortion-type sounds. The grand total of 34 setups may, at first, seem to be very generous on the part of Yamaha but I found that the difference between several of the effects configurations was somewhat subtle. Perhaps better ears than mine would disagree...

"...programming the TG55 is a bit like trying to wallpaper the hallway through the letterbox!"


The TG55 really starts to shine when you take advantage of its multitimbral capabilities. The TG55 can have as many as 16 different sounds playing at the same time, providing you don't run out of elements in the first instance. Notes are dynamically assigned amongst the various sounds so that you shouldn't run out when it matters most. Also, you can reserve a specific number of notes for particular MIDI channels, if you so wish.

If I have a criticism, it's to do with the way the TG55 deals with the problem of note-stealing, which occurs when you try to sound more than 16 notes at any given time. The TG55 uses the time-honoured 'oldest note' algorithm for reassigning a note, whereby the note that has been held the longest gets the chop in favour of the new note. In practice, this approach works fairly well - but it is not an ideal solution. The better approach would be to use a combination of the oldest note and the quietest note, so that the absence of the 'stolen' note is not so apparent.

Overall, I found the Multi capabilities of the TG55 particularly easy to use, which made a refreshing change when compared to the voice edit facility.


The TG55 can't really be regarded as a giant leap forward in terms of its synthetic abilities. Most of the facilities that the TG55 boasts have been around for some time now, and Yamaha have basically set out to try and improve on the specifications of such machines as the Korg M1R and Emu Proteus. In some areas they have succeeded, in others they haven't. Knowing something of Yamaha's prowess in the field of digital design, I was seriously hoping for a greater degree of polyphony. In this respect, Proteus still comfortably rules the roost. The filter section is excellent and imparts considerable strength to the machine, rather than existing merely as an afterthought. Although it lacks the character of old analogue filters, it is more than up to the job.

Although Yamaha boast that the TG55 features 'state of the art' digital circuitry, the same cannot be said of the software programming. The overall feel of the software is that it is a bit sloppy and has been implemented without sufficient thought to the end user. This opinion is sadly confirmed when you consider the poorly laid out front panel. My overall impression of the TG55 is that the top level design of this instrument could benefit from a re-think in certain areas. This may seem to be a rather harsh attitude to adopt, but it's software of this standard that will consign the TG55 to a rather anonymous existence within many a 19" rack, alongside many other anonymous units with equally unfriendly user interfaces!

The TG55 has all those important 'today' type sounds readily to hand and the quality of those sounds is sonically excellent. Consequently, it should be an instant hit with the public. To the synth purist it offers considerable power, provided that you're willing to put up with a bit of intellectual discomfort. The alternative is to wait for a computer-based voice editor or a dedicated programmer, as in the case of the Korg M3R and RE1. The TG55 is one module where the remote voice editor is not only desirable but practically essential.

Having spent quite some time getting into the TG55, casting aside some of its slightly irritating quirks, I can say that I thoroughly enjoyed myself and genuinely missed this instrument when it eventually had to be returned. My final impression of the TG55 was that it presents something of a rather curious paradox - a sample playback instrument with a personality of its own!


£749 inc VAT.

Yamaha-Kemble (UK) Ltd, (Contact Details).


  • Tone generation: AWM2, 16-bit linear; 32/48kHz sampling rate.
  • Polyphony: 16 notes (maximum); 16-voice multitimbral.
  • Filters: Real-time digital filters (Low Pass, Low/High Pass; 12dB); maximum of 8 for each Voice, with resonance.
  • Digital effects: 34 reverb programs.
  • Internal voice memory: ROM: 64 Voices, 16 Multi settings. RAM: 64 Voices, 16 Multi settings.
  • Internal wave memory: 2 megabytes External storage: 2 card slots (for Voice parameter and Waveform data).
  • Connections: 2 sets of stereo output (4 individual outputs); headphones; MIDI In, Out, Thru.
  • Display: 2-line backlit LCD.

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Shure Beta Microphones

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Recording Techniques

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 - Mar 1990

Gear in this article:

Synthesizer Module > Yamaha > TG55

Gear Tags:

Digital Synth

Review by David Hughes

Previous article in this issue:

> Shure Beta Microphones

Next article in this issue:

> Recording Techniques

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