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Yamaha MU128

Sound Module By Simon Trask
Published February 1999

Yamaha MU128

Yamaha's latest XG MIDI module achieves more onboard sounds and greater polyphony and multitimbrality than previous tone generators — and allows users to install additional synthesizer and effects boards. Simon Trask explores the power of MU...

The MU series of GM/XG sound modules from Yamaha emerged in the mid‑'90s as the company's response to Roland's SC series of GM/GS modules. In essence, they are playback modules rooted in the General MIDI tradition of sonic standardisation and categorisation, as opposed to the category‑busting experimentation of creative synthesis. Another tradition — that of competition — has seen successive flagship releases from both companies steadily up the number and quality of both sounds and effects, as well as the amount of polyphony and multitimbrality available, resulting in modules which are impressively powerful and versatile while retaining the core attributes of GM.

With their latest addition to the MU series, the MU128, Yamaha are aiming to show that there's still more mileage to be had from the MU/XG concept. As well as providing more sounds, polyphony and multitimbrality than ever before, Yamaha's new MU module also lets users plug in daughterboards which augment the module's sample‑based sounds and internal effects with additional synthesis methods and effects processing.

The Numbers Game

The MU128's rear panel features two sets of MIDI ports; those wishing to take
advantage of its 64‑part multitimbrality will need to connect it to a computer via the To Host serial port connection.The MU128's rear panel features two sets of MIDI ports; those wishing to take advantage of its 64‑part multitimbrality will need to connect it to a computer via the To Host serial port connection.

Yamaha's approach to naming their MU modules follows a couple of simple rules: the more powerful the module, the bigger the number, while if it's a rackmount as opposed to a desktop module then an R needs to be added on the end. Accordingly, the MU128 is the most powerful MU module yet, not just incrementing but doubling the polyphony and multitimbrality of the previous flagship MU100R, and further upping the number of sampled sounds. It also sees Yamaha reverting to the desktop module format, having previously gone rackmount with the MU90R and MU100R.

Rather impressively, the 128 of the module's name equates to the amount of polyphony it offers, while the multitimbrality is an equally impressive 64 parts, receiving on up to 64 MIDI channels via the module's rear‑panel To Host serial port connection. In its XG mode, theMU128 offers a choice of 1149 Voices (Yamaha's name for sound programs, or patches) and 37 drum kits. The module also has a TG300B mode (for compatibility with the GM‑B mode of Yamaha's pre‑MU TG300 Tone Generator), which offers 664 Voices and 10 drum kits, giving a total of 1342 Voices and 47 drum kits (some of the Voices being common to the two modes). A third mode, Performance mode, provides patch memories which combine up to four Voices on the keyboard in split/layer textures which are playable via a single MIDI channel. Like the earlier MU80 and MU50, the MU128 is a half‑rack unit designed to sit comfortably next to a computer. Unlike them, however, it's 2U rather than 1U high. This is so that it can accommodate up to three plug‑in daughterboards, which fit into an expansion bay in the lower 1U space of the module. So far three boards are available, offering respectively FM synthesis (PLG100DX), physical modelling (PLG100VL), and vocal harmonisation (PLG100VH), with further additions planned (though no details are available on these as yet). While the MU100R came with pre‑fitted VL and Vdaughterboards, the new module is the first to allow users to plug boards in themselves (see the 'Board Talk' box for details on installation).

The module's 2U height also means that, despite being a half‑rack unit, it can retain the data entry dial of the MU90R and MU100R, and add a second, alternative MIDI IN A socket and an array of individual Voice category select buttons on the front panel. The latter allow you to jump straight to the first Voice in each GM/XG instrument category, the GM/XG drum kits, or a bank of Voices which doesn't conform to the GM ordering. The small buttons and cramped layout make front‑panel operation a fiddly business physically, yet the streamlined user interface and the large, informative LCD with its graphical, iconic approach and large text allow you to find your way around the module fairly quickly and easily.

Voices, Parts And Effects

The MIDI In A port is reproduced on the front panel, along with two audio inputs. These can accept mic, instrument or line‑level signals for processing using the MU128's onboard effects.The MIDI In A port is reproduced on the front panel, along with two audio inputs. These can accept mic, instrument or line‑level signals for processing using the MU128's onboard effects.

There are two types of XG Voice: Normal and Drum. The former are pitched instrumental Voices, while the latter contain only drum and percussion sounds. Each of the MU128's 64 Parts can be assigned one Normal or one Drum Voice; with the latter, you can select one of the 37 available preset kits or one of four global user‑edited kit memories (drum S1‑S4). The new module also follows the MU90R and MU100R in providing two additional Parts in the form of front‑panel A/D jack sockets into each of which you can plug a microphone, guitar or synth: audio received at these sockets can be run through the same multi‑effects architecture as the other XG Parts.

A normal XG Voice consists or either one or two Elements (sampled sounds), with each Element requiring one voice of polyphony. While this means the maximum polyphony is only available if no two‑Element Voices are used, the MU128's generous 128‑note polyphony means there are plenty of voices to go round. Like Roland's rival GS format, Yamaha's XG MIDI extends General MIDI by providing Variations on the 128 General MIDI sounds. You use MIDI program numbers to select the type of GM sound, and MIDI Bank Select LSB values to scroll through the available variation sounds for each GM sound. In this way the standardised GM organisation of sounds is maintained, while any alternatives to each of the 128 basic sounds can readily be selected.

There's a warmth, fullness, vitality and depth to the MU ensemble sound which is very appealing.

What you can't do on the MU128, or any of the other MUs before it, is edit any of the Voices directly. Assigning different samples to the Elements of a Voice is definitely verboten — after all, it would be completely going against the grain of the XG Variation concept. Again like Roland's SC modules, relative sound edits to a limited number of synthesis parameters can be made at the Part level. Consequently, if you select a different Voice for a Part mid‑song, any edited settings will be applied to the new Voice, whether appropriately or otherwise. With so many Parts available on the MU128, it makes sense to simply assign the different Voice to a different Part instead, where you can give it its own sound edits if necessary. You may also need to be clever about switching Insertion or Variation effect Part assignments using SysEx commands embedded in your sequence, but a handy Show MIDI Data function on the module can help you out here.

So what can you do to change a Voice? At the synthesis level, you can edit filter, EG and vibrato settings. For the filter section you can adjust the programmed low‑pass cutoff frequency, and resonance and high‑pass cutoff frequency values. You are offered control over the attack, decay and release times of a common level/filter EG, as well as the initial level, atack time, release level and release time of a separate pitch EG. You can also play with pitch by changing vibrato rate, depth and delay settings. In addition, each Part has its own two‑band EQ, and you can change frequency and gain individually for the low and high bands. Send amounts for the reverb, chorus and variation effects can also be set per Part. Further Part‑specific parameters include volume, pan, note shift (+/‑24), MIDI receive channel, note and velocity high/low limits, mono/poly play, portamento on/off and time, and settings for pitch bend, mod wheel and assignable controller response. There are also several All Part parameters: master volume, master attenuator, transposition, and reverb, chorus and variation return levels.

Drumkit editing on the MU128 is impressively versatile. Starting with one of the preset kits, you can change parameter settings for each sound in the kit (though you can't select different sounds), after which you write your edited kit to one of the four user kit memories. For each individual kit sound, you can set parameter values governing pitch, level, pan, effect send levels, filtering (including resonance), two‑band EQ, EG attack and decay, alternate group assignment (for specifying which sounds will cut each other off), and whether or not the MU128 responds to MIDI Note Ons and Offs.

In addition to the two‑band EQ available for each Part, the MU128 provides six other effects: Reverb, Chorus, Variation, Insertion 1, Insertion 2, and Multi EQ. The first two are System or global effects common to all the Parts, while the third can be global or Part‑specific depending on whether you set the effect configuration mode to System or Insertion. Global effects have Part‑specific send levels, while the two Insertion effects and Variation‑as‑Insertion can each be assigned to any one of the 64 Parts — so, for instance, three Parts could each have one effect, or one Part could have three effects in series (Insertion 1 — Insertion 2 — Variation). In addition, the System effects can operate in parallel or in series, with the latter further controlled by the send levels along the chain Variation — Chorus — Reverb.

The Multi EQ is a five‑band equaliser (Low, Lo Mid, Mid, Hi Mid, High) which can be used to adjust the final, effected stereo signal by means of 12dB cut/boost on each frequency. There are five preset EQ settings that you can choose from (Flat, Jazz, Pops, Rock, and Concert), and you can also use these presets as a starting point for creating your own settings. It is advisable to save these, as with any edits you make in the course of creating a song environment on the MU128, to a sequencer or data filer as part of an All or Multi MIDI SysEx dump.

Putting On A Performance

The MU128 provides 100 preset and 100 user‑programmable Performance memories. A Performance can utilise either Parts 1‑4 or Parts 1‑2 plus the two A‑D Parts. With the former option, up to four Voices canbe combined on the keyboard in split/layer textures (excluding drum Voices), as each Part can have its own note range and velocity range. Alternatively, you can have a simpler keyboard texture but at the same time use the MU128 as an effects processor for vocal and/or guitar parts. As with Parts in multi mode, the MU128 provides both Single and All Part parameter editing. The same parameters are available for each Performance Part as for a Part in multi mode. You can also solo and mute Parts, which can be useful for editing as well as performance. If you have a DX and/or VL board installed, you can use a Voice from each board within a Performance along with the MU128's internal sample‑based Voices. The factory MU128 Performances obviously use only internal MU128 Voices, but the CD‑ROM that comes with the module (see 'Tools Of The Trade' box) includes additional Performance sets which utilise sounds from these boards. Performances can be selected and played via the module's MIDI In A socket or port one on its To Host connection, with all the MIDI Parts automatically assigned to the same channel (which is user‑progammable globally in Utility:System edit mode).

Rather impressively, the 128 of the module's name equates to the amount of polyphony it offers, while the multitimbrality is an equally impressive 64 parts.

Performances let you play sound combinations and textures that you can't get with single Voices; on the other hand, you lose the extended MIDI multitimbrality of the MU128's XG and TG modes. Yamaha's view is that Performances are intended for live performance work rather than sequencing (hence the name, of course). However, if you think otherwise, you can create a Performance‑type texture for sequencing use in multi mode — you simply assign several Parts to the same MIDI channel and program the required Part settings. This way you can create textures of more than four Voices, but each texture you use within a song will need to have its own Parts. An alternative would be to (re)create some or all Performance settings on a suitable multi‑zone MIDI controller keyboard, transmitting on multiple MIDI channels to the MU128 via a sequencer.

In The Lead

The MU128 has two MIDI In sockets, A and B, respectively controlling Parts A1‑A16 and B1‑B16 for up to 32‑part MIDI multitimbrality. If you want to use more than 32 parts you'll need to run a serial cable from the module's rear‑panel To Host socket directly to a serial port on your computer (Mac or PC). This way, providing your sequencing setup can address multiple virtual ports (and any professional sequencing package should be able to do this), you can address all 64 of the MU128's Parts over the serial cable via ports 1‑4 (ie. 4 x 16 MIDI channels). The MU128 can even route MIDI data received on a fifth port (user‑definable in System mode) directly to its MIDI Out socket, so you can run an additional 16 channels on one or more external MIDI instruments. Not only does the To Host option give you access to all 64 Parts, it also removes theneed for a separate MIDI interface, and allows you to use more than 16 MIDI channels without having to invest in a (more expensive) MIDI patchbay. The serial lead connection is two‑way, so you plug your keyboard controller into the MU128's MIDI In and its data is sent via your sequencer back to the module before it triggers any sounds. To play the MU128 while your computer is powered down, you simply set the module's rear‑panel Host Select switch to MIDI rather than Mac or PC. Two‑way serial port communication also means that identity polling, parameter requests, and MIDI data dumps from the MU128 are handled transparently. One possible problem with the To Host approach, however, is that Mac and PC serial cable lengths are limited to two and 1.8 metres respectively, but if you have a relatively compact, desktop‑type setup this shouldn't be an issue.

On The Winning Team?

The key advances that the MU128 brings to the MU range are a doubling of polyphony and multitimbrality and the opening up of the plug‑in architecture first introduced on the MU100R – ie. the fact that users can plug in complete synthesizers and effect processors on daughterboards. Sonically the MU128 represents familiar MU/XG territory in the character, quality, array and organisation of its Voices. This is an all‑round (and a well‑rounded) instrument, providing an impressive number and variety of sample‑based sounds, which are strongest in ensemble use — its primary intended application, of course, is playing back GM/XG songs. There's a warmth, fullness, vitality and depth to the MU ensemble sound which is very appealing. A classy, versatile multi‑effects section plays its part here; although the MU128 doesn't offer any advances over previous MU modules in this department, the quality and number of effects provided is already impressive (Insertion effects on more than the usual two Parts would have been welcome, though). The familiar effectable audio inputs are, as always, a welcome inclusion. The new module is understandably more expensive than the MU90R, and with VL and Vboards fitted would be more expensive than the MU100R — but again, this is understandable given the doubled polyphony and multitimbrality and the open plug‑in architecture. All in all, if you're after the greatest power and flexibility that MU/XG has to offer, the MU128 is the module you want.

Board Talk

The PLG100VL board, based on Yamaha's VL70m module, provides 256 preset physically modelled Voices, and organises 137 of these into an XG‑compatible layout so you can readily select them as alternatives to MU XG Voices. There are also six Custom Voice memories, and an Internal bank which can accept a bulk MIDI dump of 128 Voices. You can edit many VL parameters from the MU128's front panel, but you'll need to save them as part of a bulk SysEx dump from the module; PC users can use a visual editor plug‑in for XGWorks as a superior alternative. The MU128 responds to breath control but doesn't have a breath controller input; WX wind players can play it via a BT7 box. The VL sounds make an effective addition to the sample‑based sounds of the MU128, not only providing more realistic and responsive acoustic sounds but also expanding the available palette of synthetic sounds.

As its name suggests, the PLG100DX board marks the return of FM synthesis as provided in the original DX days: six operators, 32 algorithms, 16‑voice polyphony, monotimbral (though here cleaner‑sounding). You can even edit the board's sounds from a DX7 or DX7 MkII via MIDI, and it can accept SysEx bulk dumps from these instruments into its 64 Custom memories. The board also has low‑pass and high‑pass filters and a two‑band equaliser for additional sonic control.

A wide‑ranging selection of 192 FM preset sounds organised in XG format provide a wealth of alternative sounds for you to draw on. The characteristic FM metallic quality and sense of timbral movement make a distinctive sonic addition to the MU XG sounds.

The PG100Vboard provides smooth and effective vocal harmonisation with vocoder, chordal, detune and chromatic harmoniser effects. It can generate lead and (up to three) harmony vocal parts, and includes a (not entirely convincing) 'gender changer' feature, and a pitch‑correction facility. Additional gender and vibrato parameters are settable remotely via MIDI (ie. from a software editor). You can also assign the harmoniser as an Insert effect to any one of the 64 XG Parts.

Tools Of The Trade

The MU128 comes with XGTools, a Mac/PC CD‑ROM disc containing MIDI song file demo tracks, additional Performance data, XG software and 15 short CD audio demos of the PLG boards. The six MU128 MIDI files demonstrate the module's sonic capabilities to impressive effect; especially notable are the orchestral demos, which have a richness, depth and breadth that will surprise you coming from a 'mere' XG playback instrument. To hear them in their full glory, you'll need to use the module's To Host serial cable connection and reassign tracks in your sequencer, as all the demos need to use multiple ports.

Mac users are the poor cousins when it comes to software on the disc — there isn't any. Windows users are provided with a copy of Yamaha's XGWorks Lite software as well as an update for the commercial XGWorks program (taking it to version 1.05) and four editing software plug‑ins for XGWorks: DX Easy Editor, DX Simulator, VL Visual Editor, and VEffect Editor. These are designed for use with the optional PLG plug‑in boards. Similarly, the three additional Performance data sets which come on the disc draw on Voices from these boards as well as the internal MU128 Voices. Also included on the disc are an XG Guidebook and (for PC only) the XGWorks 1.0 manual in PDF format (the necessary Acrobat Reader software for Mac and PC is provided on the disc, too). The MU128's manual and data book haven't been included as PDFs on the disc; however, they are available in (sizeable) PDF form for free download from Yamaha UK's web site (see, so you can try before you decide whether to buy.


  • Sound generation method: AWM2 (sample‑based subtractive).
  • Maximum polyphony: 128 voices.
  • Multitimbrality: 64 parts (4 x 16 MIDI channels), with dynamic voice allocation.
  • Modes: XG, TG300B.
  • Performance Voices: 1342 total (1149 in XG mode, 664 in TG300B mode).
  • Drum kits: 47 total (37 in XG mode, 10 in TG300B mode).
  • Performances: 100 preset, 100 user.
  • Effects: reverb (12 types), chorus (14 types), Variation (70 types), Insertion 1 & 2 (43 types), multi EQ (4 types), part EQ (1 type).
  • Display: custom backlit graphical LCD.
  • Connections: front panel — headphones stereo mini‑jack, audio jack inputs 1 & 2, MIDI In A socket rear panel — Left and Right audio input phonos, Left and Right audio output phonos, DC in power socket, To Host socket with Host Select switch (Mac, PC1, PC2, MIDI), MIDI sockets (In A and B, Out, Thru).
  • Expansion: up to three PLG plug‑in boards, simultaneously available.
  • Weight: 1.9kg.
  • Dimensions: 219.5mm (W) x 229.5mm (D) x 91.1mm (H).


  • Warm, full, dynamic ensemble sound.
  • Large, well‑rounded collection of sample‑based XG MIDI instrumental sounds.
  • 128‑voice polyphony.
  • 64‑part multimbrality (via computer serial port connection).
  • Plenty of high‑quality effects with versatile multi‑effects architecture, and effected audio inputs for external instruments.
  • Sonic expandability via support for PLG plug‑in boards.


  • All XG and PLG sounds are output via a single stereo pair.
  • Limited sound editing, and for Parts only.
  • Fiddly front‑panel buttons and operation.


An impressive sample‑based desktop playback module, also capable of sonic expansion utilising different synthesis methods, the MU128 is Yamaha's most powerful and versatile MU model to date — and is available at a competitive price.