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MIDItemp PMM88

MIDI Router

Midi routing systems have come a long way since the humble passive thru box. Kendall Wrightson explores a sophisticated example of the species.

MIDI routing systems have come a long way since the humble passive MIDI Thru box of the last decade. The ever-increasing number of MIDI-equipped devices and the continuing sophistication of MIDI applications has led to the emergence of MIDI routing, merging, and processing devices. More recently, 'MIDI Performance Processors' have appeared that enable any MIDI device to act as a mother/master keyboard. The MIDItemp PMM88 reviewed here contains all the features mentioned above, plus many unique ones of its own, and currently represents the state of the art in hardware MIDI management systems.


The phrase 'state of the art' could not honestly be used to describe the PMM88's appearance, for it exudes a distinctly 'DIY' feel. This is particularly true of the PMM88's remote control, which is attached to a featureless 1U rackmount 'brain' by a three metre cable terminated with telephone-style connectors.

The rack unit's rear panel contains the PMM88's eight MIDI In and eight MIDI Out sockets. The front panel sports only a mains switch and a footswitch jack. In contrast, the remote control has 14 buttons, 11 red LEDs, and a very old-fashioned looking three-digit numeric display - all crammed into a 8"x3"x1" rectangular box.


The PMM88 has three operational modes: Play, Read and Edit. On power up, the PMM88 defaults to Play mode, ready for use. The numeric display shows the currently selected PMM88 memory (1-128), and this can be incremented/decremented with the Up (9) and Down (0) buttons located to the right of the display. Alternatively, if the Mode switch is pressed, the PMM88 will allow a memory number to be punched in directly using the 0-9 buttons.

Above each of the 1-8 numeric buttons is a status LED. Pressing the In/Out Select button determines whether the LEDs represent 'sources' or 'destinations': if set to 'In', an illuminated status LED indicates that a destination is assigned to that source; if set to 'Out', an illuminated LED indicates that a source is assigned to that destination.

Any MIDI input or output can be switched off immediately, without having to enter Edit mode, simply by pressing any 1-8 button: if on, it will toggle off, and vice versa. When disabling outputs in this way, the PMM88 also transmits an All Notes Off command to prevent any notes already sounding from sticking on. When disabling inputs, a double click of the button will send an All Notes Off command to all outputs assigned to that input.

So, checking a routing arrangement where there is only one source assigned is simply a case of pressing In/Out Select and then noting which LEDs are illuminated. However, if multiple sources are assigned, each source would need to be checked individually by deselecting the other sources, flicking to Out to see the destinations, flicking to In to select another source, and then flicking to Out and so forth. This procedure takes a lot less time to perform than it does to read, I assure you.

To actually discover what devices are connected to each of the inputs and outputs, without the need to disconnect cables, the PMM88's 'MIDI Eye' function can be used. With the Eye on (initiated by pressing the Mode button twice followed by the Read button), the 1-8 status LEDs flash in sympathy with data at their corresponding MIDI In or Out socket (selected by In/Out Select).

As you have no doubt realised by now, the PMM88's user interface is unlikely to win any awards, and the manual will have to be studied. It's a wise PMM88 user who keeps a source/destination and memory assignment list to hand. But please don't get disheartened - it's all good news from here on in!


Straightforward input to output routing is easily achieved by pressing the Edit button, selecting a source with the 1-8 buttons, toggling the In/Out Select to 'Out' and selecting your chosen destinations (again, using the 1-8 buttons).

This process is then repeated for each source and the result can then be memorised by pressing the Mode button and punching in the number of the desired PMM88 memory location (1-128). With a final press of the Mode button, the PMM88 returns to Play mode.


If several sources are routed to the same destinations in the above programming routine, the PMM88 automatically merges the data from each source without further ado - no special modes to enter, no considerations to be met.

The PMM88 is unique in allowing up to 8-way merging. This means, for example, that you could have several keyboards plus a drum machine, drum pads, and a MIDI guitar all connected to your sequencer simultaneously, and record note information etc from up to eight instruments at once.

However, it is important to remember that MIDI merging is not infallible and that if too much information is transmitted in any one moment, there will be a delay and/or data will be lost.

The reason for this is that a single MIDI command (like a 'Note On') is made up of several smaller packets of information, called bytes. The first byte of any message is called a 'status' byte, and it indicates the nature of the 'data' bytes to follow. When merging two inputs, A and B, the MIDI protocol insists that information from input B cannot be inserted between input A's status byte and its corresponding data bytes - so the processor has to wait until all input A's data is passed before it can transmit input B's data.

This limitation is particularly noticeable when merging MIDI Clock or MIDI Time Code (MTC) data, generated by a synchroniser, with live keyboard data in order to record 'in sync'. MIDI Clock and MTC data is dense, so it's very easy to cause audible delays when playing fast chords with lots of controller action, because timing (clock) information takes priority over all other kinds of MIDI data in the merging process.

(In the above situation, the only realistic solution is not to record in sync, or to utilise a sequencer or computer with several independent MIDI ports.)

Essentially then, 8-way merging is a great convenience feature - the ability to swap between instruments when recording allows for greater spontaneity and improvisation.


Simple A to B connection is just a fraction of the PMM88's capabilities. A feature called 'multiconverting' allows the PMM88 to route (or filter) all 16 MIDI channels of any input independently. For example, a sequencer on input 1 might be transmitting data on channels 1 to 4. Multiconversion allows each of input 1's channels to be routed to different outputs.

This facility has several practical uses. Firstly, it means that data need not be transmitted to devices to which it is irrelevant. Multiconversion could be a life-saver when gratuitously pitch bending, as it will keep the data traffic per output down to a minimum. Secondly, it allows older or adapted 'Omni Mode only' synthesizers to be connected and to receive on any MIDI channel.

To programme a multiconversion, the standard routing procedure of selecting an input is followed. At this point, a MIDI channel can be selected with the Up/Down buttons before selecting an output destination in the normal way.

A feature called 'manifold' is a further extension of multiconversion. In essence, it means that data on MIDI channel 1, say, can be programmed to re-transmit on channel 2, or 3 and 4, or indeed any combination - even on all 16 channels simultaneously. The practical application of manifold is that multiple channels of a multitimbral synth can be played together (or several voices of a Mono Mode synth).

Multiconvert and manifold have their performance applications, too. Say you had four tone modules, A to D, with module D being multitimbral and capable of playing on MID channels 1 to 16 simultaneously. In a performance, a particular song might require the following 'split keyboard' setup to match the original recording:

Intro: A only
Verse 1: A (lower) + B (upper) + C (both)
Chorus 1: A+B (lower) + D [channels 4 to 6 (upper), 7 to 9 (lower)]

Even for the latest generation of master keyboards, the above scenario would be impossible, but the PMM88 can do it with one hand tied behind its back and route a sequencer to four more tone modules at the same time!


Up to two connected keyboards (or indeed any MIDI controller: guitar, wind synth etc) can be made to behave like mother/master keyboards by using the PMM88's processing functions, which MIDItemp have imaginatively called 'Functions'.

Zoning Function 1 allows a single channel input to be split into three user-definable zones (lower, middle, and upper) with two levels of programmable velocity switching. So a standard MIDI keyboard connected to input 1 on MIDI channel 1 could be split into the following:

Soft Loud
Zone A Ch 1 Ch 4
Zone B Ch 2 Ch 5
Zone C Ch 3 Ch 6

An important point to note is that the PMM88 treats an input's MIDI Controllers as a separate independent MIDI channel, which happens to default to channel 15. This can be multiconverted to a different channel(s) and output(s), if required.

With Function 2, each zone can be independently transposed +/-64 semitones at both the input and the output! Thus you could create a complicated PMM88 memory with a split keyboard, the upper zone being transposed up by a fifth (at the input), then store another version of the memory with both zones transposed up one octave (at the output).

Program & Volume Changes Another mother keyboard style facility is the transmission of program changes (Function 6) and volume changes (Function 7). Each PMM88 memory can transmit a program and volume value per channel per output. This unique ability to predefine a volume level may even make an external mixer unnecessary in certain performance situations.

MIDI Clock Function 9 allows for a preset MIDI Clock to be transmitted from any or all of the PMM88's eight outputs, at a user-defined rate (40-255 bpm). The Clock can be made to start immediately a PMM88 memory is recalled, or a manual start can be initiated in Play mode by pressing the Mode button twice, followed by the In/Out Select button. Pressing In/Out Select once more stops the MIDI Clock, and double-clicking it continues the Clock). For songs without tempo changes, the MIDI Clock facility provides centralised control for live performance, and frees the sequencer from having to generate MIDI Clock data.

System Exclusive Function 5 provides the opportunity to utilise knowledge gleaned from Martin Russ's excellent 'System Exclusive' series of articles [see SOS April 1989 to March 1990]. Up to 88 bytes can be entered (in decimal or hex) for transmission of customised SysEx messages. Two examples of this facility are transmitting Dump Request and Local On/Off messages.

Transparent Panic Function 8 is called Transparent Panic because, instead of transmitting an All Notes Off message (which some MIDI devices don't recognise), the PMM88 transmits individual Note Offs and Controller Reset values on every channel for every output. It's possible to continue playing whilst a transparent panic is underway, as connected devices will not shut out data as they do once they have received an All Notes Off.

The final processing facility is Function 0, which allows the PMM88 to dump its 128 user memories to a sequencer, librarian, or bulk data recorder. A transmission delay between each data block can be defined, up to 120 milliseconds, to aid compatibility when dumping SysEx data.


A sort of sub-mode, 'Installation' adds a further selection of useful facilities to the PMM88's already massive arsenal.

For performance applications, it's possible to select PMM88 memories via a MIDI program change. This is done by designating one of the eight inputs as a 'master' input. Once designated, program changes received on that input (on a user-defined MIDI channel) will not be re-transmitted but interpreted as a PMM88 memory selection instead.

For keyboards that organise their Presets into Banks, the PMM88's 128 memories can be divided into two banks of 64, four banks of 32, or eight banks of 16. Not surprisingly, this feature is called 'Banking'.

'Program Split' is the PMM88's piece de resistance, offering the ability to define two independent Master inputs. This means that two players (or one player and a sequencer) can change the PMM88's memories via program changes. Furthermore, both Master inputs can have independent mother keyboard processing setups access all eight outputs.

It is important to be aware that the PMM88's on-board memory is finite; when full the display reads 'F', and no more programming can take place unless the memory is dumped to disk or other memories are cleared to make more room.

Hint: as you will have realised if you've read this far, a PMM88 memory can contain many elements and convoluted routing possibilities. For this reason, it's best to write down an intended configuration step-by-step before attempting to programme it, otherwise tears before bedtime are extremely likely.


With the proliferation of computers for MIDI applications, many manufacturers have developed combined MIDI interface/synchroniser/routing devices for their chosen computer. Mark Of The Unicorn, for example, recently announced the MIDI Timepiece interface for the Apple Macintosh and have adapted their Performer sequencer program so that Timepiece's eight MIDI outputs can be addressed individually from each track, giving 128 channels of MIDI.

In this way, data can be assigned to an alternative MIDI output should one become overloaded. Such overloading occurs much more frequently these days, particularly when pitch bend, aftertouch, and volume controllers are being transmitted on several MIDI channels simultaneously.

Although the PMM88 is not designed to work with any specific software or computer, it has its own methods of re-distributing MIDI data to ease congestion, as noted earlier. However, the computer interface/synchronisers mentioned do not permit processing or MIDI performance facilities of the kind offered by the PMM88. Also, for the professional studio, a full specification synchroniser and a large MIDI matrix would be preferable.

The PMM88 does not pretend to be a SMPTE synchroniser, but its ability to generate a MIDI Clock with Start, Stop, and Continue commands is very useful for performance applications.


Comparing the PMM88 with its more direct competitors, its £449 price tag is pretty competitive. Roland's A880 MIDI Patcher/Merger offers 8x8 routing but with no multiconvert/manifold style facilities, no MIDI performance features, and merging restricted to (any) two sources.

The most direct competitor to the PMM88 is Digital Music Corporation's MX8 MIDI Patch Bay/Processor [reviewed SOS August 1988]. For £339, the MX8 offers many of the PMM88's MIDI performance features including four definable zones, velocity switching, filtering, channel shifting, and transposition. It also has a dual MIDI delay (up to three seconds) to create MIDI echo effects, a MIDI compander (to scale velocity sensitivity), and the ability to name and display its user memories in the 32-character fluorescent display - features not found on the PMM88. Best of all, DMC also offer MX8 Editor/Librarian software for the Atari ST for an extra £70.

On the downside, the MX8 is a six In, eight Out design with merging limited to (any) two inputs. Furthermore, it offers no multiconvert/manifold facilities and only one input can be assigned Master status.

Two features absent from all the devices compared above are controller conversion (ie. turning sustain pedal data into pitch bend data), as found on the old Yamaha 4x4 MEP4, and matrix expansion. The Sycologic M16 (no longer available) was a 16x16 design capable of expansion to 16x32 and 16x48 by the addition of up to two 16 Output expander units. These expanders plugged into the main unit via a multi-way connector and came under its control. For the Roland, DMC, and MIDItemp devices, expansion is not possible without the purchase of a second unit. It may well be possible to control two units from a common remote control or software package, but probably not without some software or even hardware tinkering.


For under £200 there are many straightforward MIDI expanders available, ranging from simple Thru boxes to the Akai ME30P, which offers 50 patches of 4x6 routing with two-way merging. For the larger setup, the Roland A880 represents an economical rack-mounting solution for no frills 8x8 routing with a MIDI merge facility. The DMC MX8, like the MIDItemp PMM88, fulfills both studio and performance roles with equal elan. However, in both departments the PMM88 has the edge. Whether that edge is worth the extra £110 will depend on the likelihood of your fully utilising the PMM88's extra two inputs, multiconvert/manifold and performance features. I strongly suspect that many people will choose the PMM88 for its multi-merging ability alone.

Of the computer interface synchronisers/routers available, Mark Of The Unicorn's MIDI Timepiece, Steinberg's SMP24 and newly announced MIDEX, and C-Lab's Unitor are worth investigation for Performer, Pro24/Cubase, and Creator/Notator users respectively. Each offer multiple independent MIDI Outs and may well be all you need to satisfy your present routing requirements.

MIDI management systems like the MIDItemp PMM88 are as important to MIDI data as the mixer is to audio data, yet they rarely receive the attention they deserve. Perhaps this is due to the perceived complexity of MIDI, or that such systems lack the apparent excitement of the latest 84-bit synthesizer. However, like the all-singing, all-dancing megasynth, the PMM88 performs amazing feats with just a little imagination.


£449 inc VAT.

MCMXCIX, (Contact Details).

Also featuring gear in this article

Miditemp PMM88
(MT Jun 90)

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Dr.T's Copyist

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Studer Dyaxis

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 - May 1990

Donated by: Bert Jansch / Adam Jansch

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MIDI Patchbay > MIDItemp > PMM88

Previous article in this issue:

> Dr.T's Copyist

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> Studer Dyaxis

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