If monophonic multitimbrality seemed like a dream to you MIDI sequencer users, Ensoniq's implementation of polyphonic multi mode is going to have you believing you've woken up on your birthday.

NOW THAT MIDI sequencing is a commonplace feature of modern music-making, multitimbral operation has become almost a prerequisite feature of new synths. The MIDI 1.0 spec provides for multitimbral transmission and reception in the shape of MIDI Mode 4 - also known as "mono mode" because it only allows monophonic performance on each MIDI channel. The idea of mono mode is that a synth can allocate each one of its voices to consecutive MIDI channels from the base MIDI channel upwards. Each voice can then be given its own patch, so you end up with several instruments for the price of one.

Casio's CZ101/1000, one of the earliest synths to implement mono mode, is capable of receiving on four MIDI channels at once, each with a different sound assigned to it. MIDI Mode 4 still has its uses (notably in conjunction with MIDI guitars). Realistically, monophonic response on each channel was never going to be enough for sequencing applications.

Instead, today's generation of multitimbral MIDI instruments employ "multi mode". This isn't a fifth MIDI mode; the official line (the gospel according to the MMA and JMSC) is that multi mode is simply a means of identifying a MIDI instrument that receives polyphonically on multiple MIDI channels. As this essentially emulates multiple instruments receiving in omni off/poly mode (MIDI Mode 3) it was decided that a fifth MIDI mode wasn't needed.

In fact, multi mode was a spontaneous development on the part of the instrument manufacturers, who realised that they needed something more than mono mode if their instruments were to be attractive to recording musicians - and weren't about to wait around for some committee to thrash out the details.

The competitive spirit being what it is, manufacturers have gone ahead with their own ideas of what multi mode should be. The result? You'll find varying degrees of sophistication employed in the name of multitimbral performance over MIDI. So just because an instrument claims to have multi mode, don't presume that it'll have all the features of that other multitimbral synth you read about - it might have more.

Essentially the differences boil down to whether a multitimbral instrument's voices are allocated dynamically to the different sounds or whether they have to be pre-assigned, and whether each sound can respond individually to MIDI controllers or whether all sounds respond selectively (on/off) to controllers received on a single MIDI channel. Needless to say, these differences can affect the flexibility of a multitimbral instrument quite considerably.

Overview

ENSONIQ'S SQ80 AND ESQ1 synths both sport one of the most sophisticated implementations of multi mode. When set to multi mode the SQ80 (all references in this article to Ensoniq's latest synth apply equally to the ESQ1 unless otherwise indicated) can receive and transmit on up to nine different MIDI channels. The synth's eight voices are allocated dynamically across these MIDI channels as they're needed, with the oldest voice (s) being stolen whenever more than eight notes are required simultaneously.

Couple this ability with the fact that each channel can be assigned its own SQ80 sound (with voices adopting the sound of their current channel) and can respond independently to MIDI pitch-bend and controllers, and you get what Ensoniq refer to as nine "virtual synths" (or to put it another way: they're virtually real).

As you'll know from last month's review, the SQ80 is blessed with an onboard eight-track sequencer. Eight of the virtual synths are allocated to the eight sequencer tracks and the one remaining synth becomes what Ensoniq now call a "straight synth" - this is the virtual synth assigned to the SQ80's keyboard when no track is selected. Unlike the sequencer tracks, the straight synth can be split, layered, or split and layered (with definable splitpoint).

Selecting a track (on either the Select or Mix/MIDI pages of the sequencer section) automatically calls that track's sound onto the SQ80's keyboard - with eight-note polyphony, of course.

Making Tracks

TO MAKE USE of multi mode the first thing you must do, of course, is select it. The relevant parameter is found on the SQ80's MIDI page, where you get a choice of omni, poly, multi and mono modes. If either of the first two is selected, the SQ80 will respond only on the currently-selected track (or the straight synth); omni means the track will respond to any incoming MIDI channels, poly to the base MIDI channel only. When mono mode is selected, track one is automatically assigned the base MIDI channel and the remaining tracks consecutive MIDI channels (the straight synth, which normally receives on the base channel, doesn't respond to MIDI in this mode). Each track, or virtual synth, responds monophonically to data received on its assigned MIDI channel. With MIDI guitarists in mind, Ensoniq have implemented the global controller channel - base channel minus one. Any controller data received on this channel will be applied to all eight virtual synths.

With multi mode selected, each sequencer track sends and receives polyphonically on its own MIDI channel (set on the Mix/MIDI page of the sequencer section), while the straight synth sends and receives on the SQ80's base MIDI channel (set on the MIDI page). It's advisable to set different MIDI channels for each track and the straight synth: if the same MIDI channel is selected more than once, the SQ80 gives MIDI receive priority to the lowest-numbered track, or to the straight synth if it, is involved - the other track (s) will be silent. To play safe, assign the straight synth to MIDI channel 16.

There are two ways of looking at multi mode on the SQ80. Putting these in perspective (literally), imagine that you're either looking out from the SQ80's keyboard at your slave MIDI gear in front of you, or that you're looking out from your external sequencer at your slave SQ80 in front of you. Of course this can get a bit tricky if you're using the SQ80 as a master keyboard to record into an external sequencer which then plays back on the SQ80 in multi mode - but who said life was easy?

Let's start with recording into the SQ80's onboard sequencer. In a sense any sequencer can be thought of as transmitting in multi mode, that is, polyphonically on multiple MIDI channels.

The first thing you must do is select one of the SQ80's 60 sequences (or 30 in the case of the ESQ1). Each sequence can be thought of as a "template" allowing you to assign MIDI channel, patch number, volume level and status to each track. Whenever a sequence is selected (either onboard the SQ80 or remotely over MIDI) its associated parameter values will be selected too - and applied locally or over MIDI depending on track status.

Patches can be selected either by name on the Select page or by number on the Mix/MIDI page. Successive presses of the Mix/MIDI button step you through MIDI channel, patch number, volume level and track status sub-pages for the eight tracks.

Subject To Status

TRACK STATUS IS used to determine the response of each track (or virtual synth) to SQ80 and MIDI control. When a track is set to Local status its sound is accessible from the SQ80's keyboard (when the track is selected) or from the onboard sequencer; however, it will neither transmit nor receive over MIDI. Conversely, when a track is set to MIDI it will transmit and receive over MIDI but its sound can't be played from the SQ80's keyboard or from the onboard sequencer. Logically enough, a track set to Both will send and receive over MIDI and allow its sound to be played from the keyboard and the onboard sequencer.

"Seq" is probably the most difficult status to comprehend. When this is set for a track, data received over MIDI can be recorded into the track but won't play the associated SQ80 sound. You can use Seq status to record into the SQ80 from another MIDI instrument when you want to hear only the sound of that instrument. Similarly, a track set to Seq will play back over MIDI but won't play locally on the SQ80. It's worth spending time getting these various settings straight in your mind, as familiarity with them will make things easier in the long run.

If you're recording into the SQ80's sequencer, track status will obviously depend on whether you want that track to play on the SQ80 only, on an external MIDI instrument only, or on both the SQ80 and an external MIDI instrument. The sequencer isn't limited by the synth's own eight-voice polyphony; setting one or more tracks to MIDI allows you to record much denser sequences by incorporating the voices of external instruments.

If you're using the SQ80 as a multitimbral slave to an external sequencer, with the SQ80 as master keyboard, set the current track (or straight synth) to Both or MIDI. Both allows you to hear the SQ80 and any other instruments you may have slaved off the sequencer on the same MIDI channel. However, if your sequencer has a MIDI echo feature make sure it's turned off - otherwise you'll be playing two notes on the SQ80 for the price of one.

Probably the safest option is to set one of the SQ80's tracks (or, again, the straight synth) to MIDI. This effectively puts the synth into local off mode: the keyboard plays out over MIDI only, while the synth's voices are triggered by incoming MIDI data. As almost every sequencer allows you to re-channelise incoming MIDI data, it doesn't really matter what channel your chosen transmit track is set to; equally you can play any of the SQ80's virtual synths via the sequencer by re-channelising to the appropriate MIDI channel (or avoid the SQ altogether by re-channelising to a channel that the synth isn't receiving on).

While patches can be called up on individual tracks at any time, it's also possible to call up SQ80 sequences (sets of eight patches, with associated volume level and track status settings) by means of MIDI song selects. These must first be enabled on the MIDI page. Obviously your external sequencer will need to be able to record these commands within one of its tracks (or allow you to insert them in a track), and there mustn't be any other MIDI devices in your system which will respond to song selects. SQ80 songs 1-20 are called up by song selects 0-19, and sequences 1-60 by song selects 20-79. Because the SQ80's dynamic voice assignment doesn't interrupt any sounding voices when new patches are called up, there's a smooth transition from one set of eight patches to another.

Clearly, then, the SQ80's flexible implementation of multi mode makes it ideally suited for sequencing applications, whether you're using the onboard sequencer or an external sequencer.