Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

Miditemp PMM88

As your MIDI studio expands, MIDI management becomes more and more important. Vic Lennard investigates an 8x8 MIDI patchbay that could make your music more important than your MIDI leads.

Even small MIDI studios have now grown to the point that MIDI data management is essential. MIDItemp have added MIDI merging and programmability to an 8x8 MIDI patchbay to provide just such a management system.

MIDI SYSTEMS ARE becoming more sophisticated - seemingly by the day. This is good news in many respects, but greater sophistication in the units actually using MIDI data is making MIDI "management" a correspondingly large problem.

Some three years ago the first MIDI patchbays began to appear. The principle behind them was simple: to do for MIDI patching what audio patchbays did for audio signals - and the engineers having to work with them. Instead of having to reach behind racks of equipment to swap a lead from one socket to another, it could be done from a patchbay - saving time and frayed nerves. But MIDI data streams demanded more than their audio counterparts. Merging MIDI data, filtering out unwanted messages and transferring the data appearing on one MIDI channel to another are examples of aspects of MIDI management which had not really been considered when those first MIDI patchbays appeared.

Today the trend in MIDI patchbays is towards units which incorporate merging and filtering facilities along with the ability to store and recall patches in a similar way to that in which synths manage their sounds. One such up-to-date patchbay is MIDItemp's PMM88.


THE PMM88 COMES in two parts. The first is a 1U-high rack-mounted processing unit in a rather dashing silver-grey colour (makes a change from black). This has 16 MIDI sockets on the rear (eight In, eight Out) and nothing but a power switch and a footswitch socket on the front.

The second unit is a remote control front end which is connected to the "business" half via a nine-pin socket. The standard connection cable length appears to be three metres, although up to ten metre cables are available.

The remote unit has buttons numbered one to eight which have three purposes; to show which of the eight PMM88 channels are set to receive and send MIDI data and, in conjunction with the Mode button, to call up one of eight different processing functions. Each of these buttons has an allocated LED. The "In/Out Select" button selects whether the MIDI In or Out is being examined. Buttons "9" and "0" double up as "up" and "down" and there is a three-character display to show what is currently being edited.


IGNORING THE ABILITY of the PMM88 to process MIDI data for the present, let's have a look at setting up a basic patch. Pressing Edit followed by In/Out Select allows you to select one of the eight MIDI Ins - which will be coming from a MIDI controller, perhaps a master keyboard. Let's say that In 1 is chosen - the LED above it starts flashing and you are now routing the MIDI data from this keyboard to the/sound modules connected to the MIDI Outs. Pressing the select button again and then choosing which MIDI Outs the input is to be connected to, say 3, 4 and 5, completes the operation. The LEDs light up to indicate the routing and you have now set a simple patch which can be saved by pressing Mode and a memory location from 1-128. Selecting a patch is achieved by either stepping through the memories via an attached footswitch, by a MIDI patch change command, or by selecting the relevant patch on the front panel.

When you're not editing, the unit is in Play mode. From here two basic tasks can be performed; using the select button you can toggle between showing the MIDI Ins and Outs set for the particular patch (indicated by the LEDs - a further press of a channel number turns that In/Out off). Alternatively, the Read button lets you see which Ins are patched to which Outs.


THERE ARE VARIOUS tasks in which merging MIDI data is either desirable or essential - using software to edit sounds on an expander and being able to play the sounds from a controller keyboard (to audition them) for one, controlling one expander from more than one controller for another.

Other MIDI patchbays have dealt with this by allowing you to assign more than one input to a merge process channel but this is invariably limited to two MIDI Ins. If you have a keyboard player, synth guitarist and drummer using MIDI drum pads who wish to play at the same time and record the result on a sequencer, you're going to need something more sophisticated than a simple two-channel merge.

On the PMM88 you can merge together up to all eight MIDI Ins by assigning Ins to the same Outs - in other words, within the scope of the PMM88, there is no limit on the number of channels that may be merged.

Because MIDI is a serial protocol, all connected devices receive all MIDI data. This can give delays and occasional problems like hanging notes and data corruption. The PMM's Multi-converting is a way around this. When selecting Edit mode, a "U" appears on the screen which means that data received at the input about to be set will pass through Unchanged. The alternative is to select a MIDI channel by using the up/down keys. Only data on this MIDI channel will be passed through to the selected Out and so to a specific sound module. In this way, MIDI devices receive only the data intended for them when driven from a sequencer or a split/layered keyboard. Neat and tidy.

Manifolding is an extension of this process. An input MIDI channel can be selected and the MIDI data duplicated to any of the 16 MIDI channels. For instance, data received on MIDI channel 1 could be converted to channels one to six - the data will be multiplied six times. A particular use for this is with MIDI mono mode 4 in which a guitar synth can play a different MIDI channel per string. A variety of 'different expanders could be played per string by this procedure.


A DOUBLE CLICK on the Mode button (shades of a mouse here) puts the PMM88 into "FUn" mode. No shades of Japanese computer games with sexual overtones here, rather an introduction to the PMM's Function mode.

Taking a tour of the PMM's functions, let's start with Split. Here one or two split points can be set per MIDI In by pressing notes on the connected keyboard. The MIDI channel for the lowest zone is set to the basic transmit channel of the synth, and this is then automatically incremented for the other zones. For example, if the transmit channel is 5, then the lowest zone will be on MIDI channel 5, the next zone on 6 and so on. Using Multi-converting this allows you to decide to which outputs data from each of these zones will go. All MIDI controller data (modulation wheel, sustain pedal and so on) is automatically assigned to MIDI channel 15, so you can decide which of the Outs are to take this data. (This includes pitchbend and aftertouch which are not technically MIDI controllers.)

Transpose allows either the entire input or split zones to be transposed by up to 63 semitones. When transposing zones, the screen shows Lo, CE or Hi for the low, centre or high zone.

Life with the PMM88 starts to get interesting with Velocity-Switch. A MIDI note velocity value can be set so that MIDI data at the input is set to the received channel if the velocity is less than that value or to a channel three greater if it is more than that value. This allows zone splits and velocity switching to be used together - each zone can be split into two regions subject to the velocity of the incoming note data. Because the lower region must necessarily have a lower velocity than the upper region, notes from the lower region sound softer. A velocity value can be added to or taken away from either region before the note data is output to balance up this situation.

A Velocity Limit can be set so that any notes with a velocity above the setting will automatically take that value. Using this with an addition value from velocity switching lets you set any velocity value for either a velocity sensitive or non-sensitive keyboard.

Filtering on the PMM covers the following options:

All data except for note on/off
All MIDI controller data
Program changes
System exclusive and common (song select, song position pointer)
System real-time (MIDI clock, stop, start and continue)

"Some of the PMM's facilities are difficult to check out - particularly those pertaining to live performance - but try as I might, I couldn't get it to misbehave."

Active sensing (input only)
Individual controllers

The PMM88 can filter on either MIDI Ins or Outs. An interesting situation is where you have split zones. As mentioned above, all controllers are assigned to MIDI channel 15 but you may wish to include, say, pitchbend with one Out and sustain pedal with another. Channel 15 would be included with each Out and the relevant data filtered out as necessary.

You can program in MIDI messages up to a total of 88 bytes per patch which will be sent each time that patch is selected as Send Data. You could send a SysEx request to extract data from a module, or a MIDI stop command to an attached drum machine.

Probably one of the best uses of this is sending a remote local on/off command to synths which cannot call up the command for themselves and so cannot function as a mother keyboard. One such instrument is the Casio FZ1. Different commands can be sent from the various Outs.

Program Change works in a similar manner to Send Data. Patch changes for individual Outs can be set up and saved per patch and sent out as the patch is called up.

With Volume Control, a preset MIDI volume command can be sent from each Out independently as the patch is called up. This allows you to balance the volumes of your MIDI modules.

Where would we be without a Panic Button? Should anything untoward happen, like hanging notes or mis-centred pitchbends, this function is guaranteed to sort it out. It should - a total of 4784 bytes are sent out from each Out which turn off all MIDI controllers which may affect performance, individual notes off and every note on every channel. This is a real belt and braces job, though I doubt whether it will often be used because an audible glitch is likely to be heard even though the transmission is gapped to take just over 6 seconds.

MIDI clocks along with start/stop/continue commands can be sent simultaneously from each Out and a tempo can be set via the up/down buttons.

All internal settings for each individual output can be saved to a librarian on a computer (or something like the Alesis Data Disk) using SysEx Dump. MIDItemp have thought of practically everything - there's even the option to set a delay between data blocks. However, I think that MIDItemp have got their maths wrong. The manual states that the data is sent out in blocks of 128 bytes and yet the entire SysEx dump is only 93 bytes.


ALL OF THE above can be set instantly by accessing the function required with a numeric key - the function name is written underneath the number - and by setting any necessary parameters.

There are a number of advanced features which will let you set the PMM88 up to go with the configuration of your equipment. The first of these is to split the 128 internal patches into either two banks of 64 patches, four banks of 32 patches or eight banks of 16 patches. Each bank has a letter assigned to it (A-H). The purpose of this is to allow you to be able to access all 128 patches from a keyboard which can call up a limited number of patches - for instance a DX7. To get to another bank, you simply call it up from the remote.

Easy to set up? Yes - double click on Mode and press Edit to take you into Installation mode. Generally, all functions can be accessed by three button presses at most.

When two keyboard players are controlling different synths via the PMM88, it would be useful to be able to split the Ins between the two players and so allow them individual access to their own programmed functions. Program split permits this. The eight inputs are split so that one set can call up one patch while the other calls up a different one. This effectively gives each keyboard player total independence within the PMM88. There has, however, to be some compromise in the processing side of the data (otherwise two independent micro-processors would be required), so the output processing only exists for the first set of Ins - although both can use input processing. Also, the second input group can independently set the program changes, volume control and bank changes.

Finally, the PMM offers two other advanced facilities. Some manufacturers allow you to set a MIDI controller other than #7 for volume - Oberheim for example - so that you can set any controller number in place of the default number. Also, the PMM88 automatically sends out an all notes off command each time you change a patch. This can be inhibited so that glitches are less likely to occur although the occasional note may hang if the patch change occurs before a note off has followed a respective note on.


MOST REVIEWERS ENJOY testing MIDI patchbays - there's a sadistic streak in most of us that wants to put this poor piece of gear through the kind of treatment that it would never receive in real life. Stick buckets of MIDI data through all Outs to all sound sources and problems are likely to occur with most MIDI patchbays - with the PMM multiconverting cures most, if not all, of these. The ability to select which modules receive each MIDI channel smooths the MIDI flow. Similarly, manifolding greatly eases data congestion when using multitimbral units in mono mode.

Obvious checks like sending a complete Korg M1 SysEx dump (heavy) through the PMM88 caused no trouble, and excessive use of a pitchbend wheel and aftertouch were handled admirably. I found it difficult to believe that some sort of MIDI data thinning-out wasn't taking place, but using a second computer and MIDI window, I couldn't detect any.

Some of the PMM's facilities are a little difficult to check out - in particular those pertaining to live performance. But try as I might, I couldn't get the PMM88 to misbehave - not even a hiccup. Most impressive.

Gripes, I've had a few - as Frank Sinatra almost sang. As the PMM88 makes up to eight-way merging feasible, checking the path from a MIDI In to any MIDI Out can be a bit awkward. A better operating system might have involved two sets of different coloured LEDs to indicate routings. Similarly, the buttons have to handle three different functions - numeric keys, MIDI on/off and function select. I can't help but feel that two sets of buttons would have made some areas of operation clearer. And any such additions shouldn't substantially increase the price.


IN A WORD, the PMM88 is excellent. It's a quality unit which can vastly improve the performance of even the most basic MIDI setup. It really is difficult to fault apart from the few points mentioned above.

On the subject of cost, a basic, MIDI-merging patchbay can be bought for half the price of the PMM88 and you're obviously going to have to be convinced that the PMM is going to make a real difference to your setup before investing the extra cash. Also, an 8x8 patchbay is a little small for many MIDI studios - it's certainly a shame that MIDItemp don't have a 16x16 version. Even so, if I had an M1, D110, sampler, computer sequencer and a couple of keyboards, I would be sorely tempted.

Price £449 including VAT.

(Contact Details)

Also featuring gear in this article

Previous Article in this issue

Age of Chance

Next article in this issue

Akai XR10

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Jun 1990

Gear in this article:

MIDI Patchbay > MIDItemp > PMM88

Review by Vic Lennard

Previous article in this issue:

> Age of Chance

Next article in this issue:

> Akai XR10

Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

If you're enjoying the site, please consider supporting me to help build this archive...

...with a one time Donation, or a recurring Donation of just £2 a month. It really helps - thank you!

Small Print

Terms of usePrivacy