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Yamaha MU15

GM/XG Mini Sound Module By Derek Johnson
Published July 1999

Yamaha MU15

Derek Johnson looks at a new baby hardware sequencer and GM/XG synth from Yamaha.

When it comes to compact, portable MIDI products, Yamaha have carved themselves a tidy little niche. Sequencer/synth combos that (almost) fit in your pocket and VHS cassette‑sized General MIDI sound modules have been a catalogue mainstay for several years, and there has been little competition from other manufacturers. Their latest entry into this market for the minuscule and mobile is the MU15, which creates a pleasing new whole from the best bits of the existing MU5 and MU10XG.

What It Is

Yamaha MU15

Internally, the MU15 is identical to the older MU10XG and MU50, with 16‑part multitimbrality, 32‑voice polyphony, General MIDI and Yamaha's extended GM (XG) compatibility. The GM/XG sound set, using Yamaha's established AWM2 (Advanced Wave Memory) technology, provides 480 sounds and 11 drum kits. Some of the instrumental voices are made up of two 'elements' and use up more of the available polyphony. Three onboard effects processors are available: two global processors provide reverb and modulation effects, while the third 'Variation' processor can be configured as an 'insert' effect, applied to one part, or as an extra global effect.

Trendy silver paint job aside, the MU15 has an identical look to the MU5, with the same large custom display and the same arrangement of buttons. The mini‑keyboard has two octaves, E to E, but octave‑shift buttons provide an effective range of 10 octaves. Navigating the MU15 involves a strip of six round buttons: the first pair steps through the 16 parts, for selecting or editing patches on each, and the second pair scrolls through the GM sounds, or alters the value of the currently displayed parameter. The fifth button is labelled 'XG Bank'. When it's pressed, the value buttons scroll through the alternate XG sounds allied to the current sound. The final button toggles between Play and Edit modes — the former for selecting voices/patches, the latter for editing the current part/voice or altering global settings. In Edit mode, each of the 25 buttons making up the keyboard becomes a parameter selector switch. The bottom row provide parameters relating to effect selection and simple voice editing, while the black keys access global parameters (master tuning, velocity value transmitted by the keyboard, local control on/off, MIDI dump and initialise) and a handful of 'part' parameters. The latter includes volume, pan, +/‑24 semitones of note shift, solo and mute.

As for connections, the MU15 has MIDI In and Out sockets and a serial port for connection to a PC or Mac. A switch adjacent to this socket determines how the MU15 will function — as a stand‑alone MIDI module, or via the serial interface. A PSU socket accommodates an (optional) external wall wart or, alternatively, six AA batteries can power the MU15. Finally, there's an audio out socket (a stereo mini jack that doubles as a line or headphone out) and a volume slider. The MU10XG's audio input, however, is absent.

Sounds & Effects

Straight out of the box, the MU15's sounds can be edited, but only to a limited extent. As it happens, the 'synth editing' parameters have been well chosen, and allow the basic sounds to be customised beyond recognition, if desired. Those parameters are:

  • Filter cutoff and resonance.
  • EG attack and release times.
  • Vibrato (LFO) rate, depth and delay.

The front‑panel controls for the effects processors produce less satisfying results: it's only possible to choose an effect type and the send amount for each of the MU15's 16 parts. The reverb processor provides 11 assorted ambiences, while the Chorus processor offers 11 modulation effects — mainly choruses and flanges. The Variation processor has a choice of 43 effects, including extra reverb and modulation effects, but extending to delays, gated and reverse reverb, rotary speaker, distortion, pitch change and more. One further edit button assigns the Variation effect to an individual part — as an insert effect — or to the whole system, accessible by all 16 parts. The last effect‑related parameter controls the dry level of a part, so that it can be balanced against the effect level. And that's it: you can't change reverb or delay times, or alter flange speeds and so on.

Under MIDI control (using MIDI controllers and/or System Exclusive data), however, the MU15 becomes more of a fully‑fledged synth; the envelope generator is multi‑stage, there's a pitch EG, and the effects become fully editable, though you still can't change a sound's basic waveform or alter its 'element' allocation, and the EG is shared by amplitude and filter.

If you're resolutely anti‑computer, a dedicated MIDI hardware controller — such as Kenton's Control Freak or Peavey's PC1600x — can be configured to transmit the necessary information to get inside the MU15. All the necessary data is in the back of the manual. Those with a computer — particularly a Mac or PC — will be better off. The same information that enables the customisation of hardware MIDI controllers could be used to set up MIDI sequencer mixer maps, or you could simply download XGEdit, a Yamaha‑endorsed shareware XG editor for Mac or PC that provides complete control over all hidden parameters — see 'Share & Enjoy' box. Of course, the MU15's memory contents can be saved via MIDI to any suitable device.

In addition to working in GM and XG modes, the MU15 can be put into TG300B mode with a System Exclusive‑triggered switch. This mode offers a different sound set related to one of the alternate operating modes of Yamaha's TG300 sound module. In practice, this boils down to compatibility with Roland's enhanced GM sound set, GS. Unfortunately, sounds from both sets can't be accessed simultaneously, as they're exclusive to their mode (there are actually 676 sounds and 21 drum kits in total hidden inside the MU15). This is particularly irritating in one respect: Yamaha's SymphKit collection of orchestral percussion is not at all standard, offering some strange voice allocations — a mute bass drum appears on C1 instead of the more usual full sound, and F1 to F2 offers some strange toms rather than an octave of tympani — while the TG300B mode's Orchestra Kit is much more useful.

In Use

Using the MU15 is fiddly, which is hardly surprising: it packs 33 small‑ish buttons onto its front panelHaving said that, the squidgy keyboard is actually fun to play. Not so good is the display, which has a limited viewing range and disappears under low light conditions; the ability to run the MU15 with batteries has obviously left power‑hungry (and expensive) features such as backlighting out of the equation, but some form of contrast control surely could have been possible.

Sonically, the MU15 is a pretty good bet. Certainly, £200 isn't buying you an EX5 or MU128, but for the portable or desktop music market it does a creditable job. Apart from the main orchestral kit, percussion is pretty good, as are acoustic and electric pianos, acoustic guitars and some ensemble strings, woodwinds and brass. Generic synth and pad sounds are also worthy — and if they're too tame for you, it's easy to tweak their filter and envelope settings. There's an unfortunate tendency on some sounds to obvious crossover points between multisamples, and some waveforms only just manage to avoid dead, buzzy or out‑of‑tune loops. But this is a side‑effect of the budget sound set: an awful lot of sonic material has been squeezed into a small ROM footprint.


At under £200, with its compact size and battery operation, the MU15 will appeal to many musicians. Those who are on the move, or who need to add a generic set of GM sounds to a studio or stage system could find that the MU15 is the answer — and as for the desktop musician on a budget, quality sound seldom comes more budget than this. Non‑computer users may also be attracted, but they'll have to be comfortable with knowing that a lot of potential will remain hidden unless extra MIDI controller hardware is used.

MU15 Brief Spec

  • 32‑note polyphonic.
  • 16‑part multitimbral.
  • 480 voices, 11 drum kits, editable.
  • GM/XG/TG300B modes.
  • Three 24‑bit effects processors: 11 reverbs, 11 modulation, 43 Variation.
  • MIDI In and Out.
  • PC/Mac computer interface.
  • Stereo mini‑jack audio output.

Share & Enjoy

Gary Gregson's £25 shareware XGEdit offers easy access to all the hidden functions of XG products — including, most usefully, all effect parameters. The well‑designed main screen is logically laid out, making the software a doddle to use.

The program can be nabbed at or, but the downloaded evaluation version has several key features — such as the ability to save edits — locked until you register. Saving can be en masse or on a per‑part basis, and there are options for saving collections of edits as MIDI Files for importing into sequences. XGEdit can be used alongside your favourite software sequencer too. There's no specific profile for the MU15 yet, but I found that the MU10 profile worked perfectly. One thing not possible with XGEdit is creating sounds from raw waveforms. You have to choose a sound that's close to what you're looking for and tweak it. Also, note that if a sound is made of two layered elements, editing is done on both elements simultaneously.


  • Low price.
  • Built‑in keyboard.
  • Highly portable.
  • Good all‑round sound set for the money.


  • Non‑backlit display.
  • Single stereo mini‑jack output.
  • Full capabilities only accessible via MIDI.


A lot of power in a very small package. For mobile or desktop musicians wanting extreme portability and consistent sounds, there's not really any competition.