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Black Box Secrets

Akai MIDI Effects

Three 19" rack-mounted modules that act as a delay, a dynamics controller, and an arpeggiator respectively. Simon Trask gives them the critical treatment.

Three rack-mounting boxes that don't have an audio output between them, let alone any sound-generating circuitry. Is this the future of MIDI hardware? Akai obviously think so.

Not content with bringing the world the first rack-mounting black box that sampled polyphonically and let you connect it to a keyboard via MIDI, Akai have now excelled themselves in producing three more black boxes - all rack-mounting, and all related directly to MIDI tasks.

The three in question are the ME15F MIDI Dynamics Controller, the ME20A MIDI Sequence Arpeggiator and the ME10D MIDI Digital Delay. Yet although their production versions are housed in the 19" rack-mounting format, photographs of early prototypes show this wasn't always the case (no pun intended).

One point to bear in mind right from the start - it might save some confusion - is that none of them has an audio output, let alone any sound-generating circuitry. They are MIDI processors, nothing more, nothing less. To this end, they process the digital MIDI data sent from your synth's MIDI Out port, and send the processed data out on their MIDI Outs. It's up to you whether you connect this signal to your transmitting synth or to another MIDI instrument altogether, or to an entire MIDI system, for that matter.

Before I go any further, a word of warning about the manuals. They aren't very clear. Which is surprising because they look as if they should be - plenty of diagrams full of clearly labelled features. But that's not the same as putting all the information together in a way which is truly informative. That, sadly, is something they are not very good at at all.

Of the three machines, it's the ME10D MIDI Digital Delay which presents its options most clearly. Consequently it's a piece of madeira cake to operate, so, being a bit of a coward, I'll tackle this one first.

To understand what a MIDI Digital Delay is all about, it's important to realise that the delay takes place in the transmission of MIDI data. All a MIDI Delay does is wait for a specified time before sending the data it's received via MIDI In over MIDI Out. Rather ironic, at a time when so many people are bending over backwards trying to minimise MIDI delays in the normal scheme of things.

The delay time is continuously adjustable from zero delay to a maximum of one second, and can give some nice effects. But there's no regeneration of the delayed signal, so the most you ever get is a single repeat of each note. Putting it against even a non-dedicated DDL like that onboard Korg's DW8000 polysynth (reviewed elsewhere this issue) makes it clear just how limited the Akai is in this respect. Then again, seeing as a MIDI-based digital delay requires synth voices to play its 'echoes', it's unlikely to achieve the sophistication of a standard DDL - your average synth would soon run out of breath anyway.

But the ME10D does have some other facilities built into it which help to make it a more versatile unit. Specifically, you can choose between octave down, octave up or normal outputs for the delayed signal. Among other things, if you set the delay time to zero, you have an octave divider effect which can be very effective. If you select Thru as well, the source signal is passed on unprocessed, potentially giving you octaves on your destination synth(s). With the right sounds, the combination of delay and octave-shifting (or even just the octave-shifting) can make a synthetic string quartet sound like an orchestra. Well, almost...

The Delay isn't able to pass on anything other than MIDI note on/off information for the delayed notes. Thus any aftertouch, pitchbend or modulation data your original notes had will not be reproduced on the delayed notes. So if you're thinking of using the delay at any point, it's best to make sure your sound isn't too dependent on performance tricks like those just mentioned.

Almost incidentally, the ME10D can also function as a MIDI on/off switch. Just switch out the Delay and Thru buttons at the same time, and the job is done. Fortunately, switching these buttons on and off doesn't result in the dreaded MIDI drone, even though the unit doesn't actually prevent on/off from functioning while notes are still active over MIDI. What appears to happen is that the Akai sends the requisite note-off commands itself, which is very sensible of it. That said, I did get notes hanging on once or twice - so tread carefully.

Also thoughtfully included is a Program Change button. As you might well guess, this switches in and out the (re)transmission of MIDI patch change data, so one moment you can be changing patches on your slave instrument(s), the next you can have a patch static while you change only the master instrument.

One of a MIDI delay's strongest plus-points is that you can decide which synths you want to pass the delayed data to. You can simply pass it back to your master synth if you want to (but remember: the notes are doubled, or even tripled if you have Thru and Delay selected, so you have to allow for this in your playing). You can send the data out to another synth and then back to your master (or back to the master and then on to the slave), while if you have a MIDI output selector or 'patchbay' unit (perhaps Akai's own Dynamics Controller — see later), the possibilities increase dramatically. So, a useful addition to any synth player's arsenal of equipment — though the delay processing could definitely have been a bit more inventive.

The essential function of the ME15F MIDI Dynamics Controller is to provide a set of master 'faders' for four adjacent MIDI channels at a time. In fact, the pre-19" version had a set of four sliders on its top panel; there are now four rotary knobs on the front panel. But the Dynamics Controller isn't entirely analogous to the common or garden fader — largely because the unit works by adjusting incoming MIDI velocity data. So it won't be much use if your receiving synth isn't velocity-sensitive.

And neither can you alter the volume of a note while it's sounding. Why? Well, as the Dynamics Controller works by controlling the attack velocity value of a note, there's nothing it can do once the note has started playing on the receiving synth(s).

What the Controller does is define a maximum attack velocity value that it can pass on, leaving you to play loudly or softly within the limits it has set. Thus, although centre click position on the four controls seems to be equivalent to MIDI's 'no velocity', you can still adjust your playing dynamics on the soft side. Turning the knobs counter-clockwise veers things towards the pianissimo, clockwise towards the fortissimo - though curiously, there's no more adjustment beyond three o'clock on any of them.

But the ME15F can act on more than just volume. Where a synth can be set to respond to attack velocity with changes in timbre, adjustments made on the Dynamics Controller will obviously define the range of timbre you can effect on the slave synth. Which is good news, as although the unit manipulates MIDI data, the effect produced is ultimately defined by how the receiving synth interprets that data.

The Dynamics Controller can affect a maximum of four adjacent MIDI channels (controlled by the aforementioned knobs) at any onetime. Flicking a switch on the rear panel gives you access to MIDI channels 1-4 or 5-8. There are four MIDI Outs on the back panel, each one assigned to outputting one of the four relevant channels. If your requirements stretch to simultaneous access to eight channels, you'll have to buy two units.

Each Out passes on data for all 16 MIDI channels, and the dynamically adjusted data for any of channels 1-8 where applicable, so there's no immediate correlation between front panel controls and MIDI Outs. There is a correlation when you select the Channel Separate facility, which converts incoming channel information for the currently selected group of four MIDI channels, to channel 1 for output on the four MIDI Outs. However, each Out only outputs data that has been received on its assigned channel, so data received on channel 4 is output on channel 1 only on the MIDI Out labelled '4/8'. Akai's reasoning behind this fairly arcane facility is that it enables synths that can't select a MIDI receive channel to respond selectively to any of the first eight MIDI channels (1-4 or 5-8).

Alongside the four MIDI Outs on the rear panel is a MIDI socket labelled 'Ext'. This is essentially a Thru socket, passing on data for all 16 channels unaltered — though if you select the Channel Separate facility, it doesn't pass on any data for the currently selected group of four adjustable channels.

The Dynamics Controller can also provide real-time mixdown facilities between two MIDI sequencers, or from one track of a sequencer to another, or allow you control over dynamics on a sequence playback. Again, you have to bear in mind the limitation of processing channels 1-8 only.

So, a useful and flexible unit, spoilt only by the way it restricts you to four simultaneous channels, and by its lamentably uninformative manual, the worst of the three.

The ME20A MIDI Sequence Arpeggiator is exactly what you expect it to be: a cross between a sequencer and an arpeggiator.

Input is in step time from your connected keyboard for both sequences and arpeggios — though as with many step-time sequencers, you can effectively play in real time if you're only using a single note duration and no rests. The unit has a maximum stated capacity of 957 monophonic sounds, but it's more than a monophonic affair (in fact, each step can theoretically be up to 128 notes polyphonic!).

Rests are input by pressing a dedicated Step button on the front panel, and tied notes by pressing the button whilst holding down the relevant notes. Akai have provided a footswitch input that performs a dual function: as a Step button equivalent in record mode, and as a start/stop controller in playback mode. And if you're wondering how you can input more notes than one or even two hands can handle at a time, the Sequence Arpeggiator doesn't move on to the next step until all note-ons have been balanced by note-offs. Thus you can hold down a chord with one hand and play all the notes you want with the other. Fiendishly clever stuff.

There are three types of input: arpeggio sequence patterns, motion chords and sequences. The arpeggio sequence patterns are performable only in conjunction with the other two, while sequences and motion chords can't co-exist; if you record one, the other is instantly erased.

Let's take motion chords first. You input a series of chords, which are then played back in one of three ways: Up, Down or Sequence. The first two arpeggiate the chords up or down respectively, while the third arpeggiates the chords upwards in the rhythm of any arpeggio sequence you've entered - if you haven't entered any, the chords are played straight. If the rhythm of the arpeggio is longer than the number of notes in the chord, the relevant number of notes is played an octave higher. If the rhythm is shorter than the number of notes, it truncates the chords.

You can easily delete an arpeggio sequence by reselecting its record mode. And just as easily, you can switch from one of the three options to another while the pattern is playing, without interrupting the flow. However, with no sort of feedback as to where you are in a sequence, and minimal editing facilities, I can't see this getting used for anything more than short patterns. So it's a shame that Akai haven't cut down on the number of notes available per sequence and made provision for a number of dynamically-allocated sequence memories. As all data input is memorised through power-down courtesy of good old battery backup, the provision of a number of sequences would have greatly enhanced the Sequence Arpeggiator's usefulness. A missed opportunity, then.

Just as an arpeggio sequence is 'imposed' on a series of motion chords, so it's automatically imposed on any sequence that you record. If you have a chord on a particular sequence step, the chord is arpeggiated in the manner described for motion chords. And where a sequence step consists of a single pitch, a rising pitch sequence translates into rising octaves in the arpeggio sequence rhythm, while a falling pitch sequence translates into falling octaves. Most strange, and not, I'd have thought, especially useful. Each step in the sequence is expanded to the duration of the arpeggio sequence (this goes for rests as well).

There are three real-time controls over playback of note data, each assigned to a dedicated front panel control. These are speed of sequence, gate time and dynamics. Gate time can be varied from staccato to legato, while dynamics operates like the controls on the Dynamics Controller. Neither of the latter are step-programmable features, though.

The Sequence Arpeggiator ignores all MIDI data apart from note on/off. So apart from the more obvious things like pitchbend and aftertouch, it won't record patch changes and, more seriously for a sequencer, can't be synced with a drum machine or another sequencer. Which really seems daft to me, because most people will want to at least sync it to a drum machine, and it could so easily have been used as an adjunct to another, more powerful sequencer.

All three Akai boxes have been inventively and (on the whole) elegantly designed. All three involve themselves only in the processing of digital data, so they shouldn't introduce any signal degradation of their own. And all three perform useful functions, both individually and in combination. What's nice is that you can buy them individually and for not much money, in true modular fashion.


ME10D MIDI Digital Delay

Performance Single delay up to one second

Controls Delay octave up/down/normal; alterable dynamic level of delay; program change enable/disable; delay and thru on/off

Interfacing MIDI In, Out and Thru

ME15F MIDI Dynamics Controller

Performance Individual dynamics adjustment for MIDI channels 1-4 or 5-8; conversion of incoming channels 1-4 or 5-8 to outgoing channel 1

Controls Dynamics on/off; Channel separate on/off; Channel dynamics controls x 4

Interfacing MIDI Out X 4; MIDI 'Ext'

ME20A MIDI Sequence Arpeggiator

Performance Chord/arpeggio and sequence recording in step time; memory retention during power-down; memory capacity 957 monophonic sounds, 128 chords, 128 chord patterns

Controls Arpeggio Speed, Gate Time and Dynamics controls (not memorised); Pattern Seq, Up and Down switches; Pattern/Chord Record switches; Step, Play and Stop switches

Interfacing Footswitch socket for play start/stop and rest input; MIDI In, Out and Thru

Dimensions 1U-high, 19" rack-mounting

Price RRP £119 for each unit, including VAT

More from Akai UK, Electronic Music Division, (Contact Details)

Also featuring gear in this article

Akai MIDI Effects
(SOS Feb 86)

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The Appliance Of Science

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Instant Sampling

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


Electronics & Music Maker - Nov 1985

Review by Simon Trask

Previous article in this issue:

> The Appliance Of Science

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