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Taking Control

Using MIDI Continuous Controllers


MIDI controllers can be used for more than just automated mixdowns — Wilf Smarties explains how to put them to some truly creative uses.

There's more to music than just notes. Electronic keyboard players have been practising the noble art of pitch bending and modulation ever since the synthesizer was invented, though MIDI made it possible to record this and other controller data into a sequencer, thereby paving the way to a whole new world of creative possibilities.

Indeed, before the value of having a MIDI filter in circuit was appreciated, many 'sequencists', (much nicer than 'sequencer users', don't you think), found that they ran out of memory whilst recording a four minute pop song, due to the huge amount of aftertouch that followed every sustained chord. The same thing happened if they made too free with the pitch and modulation wheels during a vigorous take.

This was because: 1) early sequencers had but a tiny fraction of the 1-4MB that is available to, for example, an Atari ST; and 2) controller activity generally gives rise to a vastly denser stream of MIDI data than simply hammering the ivories. A note is a note is a note, and can be specified by only a few parameters — note number (C2 etc.), velocity, note on and note off. A single pitch bend down and up, on the other hand, might send out up to 64 events on the way down, corresponding to a change in the relevant controller value from 64 (the mid-point between the limits of 0 and 127) and 0, and the same number on the way back up.

Polyphonic aftertouch (where each key on the keyboard can transmit its own set of aftertouch data) is particularly ravenous. Most sequencers give notes timing priority over controller information on playback. Nevertheless, it would be a foolhardy programmer who did not filter PAf out, should his/her keyboard be capable of generating the stuff. Perhaps fortunately, most cannot.

Pitch bend, modulation and channel aftertouch (the common or garden variety) use up but three of the 128 controllers in the MIDI specification. One or two others, such as Pan and Volume, have been generally accepted for some time and are now enshrined in the General MIDI spec, while Roland's GS goes even further, adding in, for example, Reverb and Chorus.

In a recent article I described how Yamaha make full use of MIDI controllers to control the 200 or so variable parameters of their DMP7 and DMP11 mixing consoles. Effects manufacturers, too, are offering more and more MIDI control of their programs. Where two or more devices use the same MIDI controller number (0-127) for their own ends, they must each be allocated a different MIDI channel (1-16). The DMP11, for example, needs two channels to cope with all its parameters. (The DMP7 uses note-on/off in addition to controllers, which can cause problems with modern sequencers).

Anyway, down to business... Let's look at how to use controllers to pull off some neat creative tricks. Along the way I will show you to get controller information into your sequencer in the first place, and it what ways it can be edited. I will be referring to Steinberg's Cubase 3 sequencer, which I own, and with which I am most familiar. Users of other programs will have to translate the editing features discussed here into their own sequencer's vocabulary.

PITCH TRICKS



In my experience, the most useful MIDI controller is pitch bend data. Provided it is not being inadvertently filtered out by the receiving sequencer, this information can be recorded simply by rotating the pitch wheel on your master keyboard. Depending on how the sensitivity of a voice in your MIDI sound module (sampler, M1 or whatever) is set to respond to it, this parameter can induce gentle pitch sweeps (always good through a delay line), or radical dive-bombs and virtual turntable stops. Sometimes the receiving instrument can have alternative functions assigned to this controller: In my S770 I frequently map it to the filter cutoff, which is great for 'aceed' swept resonance effects.

More recently, however, I have been using the pitch controller for pitch and timing correction, particularly in the cases of vocal and drum loop samples.

Few singers are perfect. Most hit some of the notes some of the time. In a multitrack situation, you would either drop-in repeatedly until a take was perfect, or lay parallel takes for bouncing down later. By the time most samplists have bought a sampler, there is no money left for a multitrack, and many are reduced to taking vocals either directly into the sampler, or via DAT or a similar non-drop-in-able intermediary. It is a monumental task to dissect and then re-assemble takes by sampling a word here, a phrase there etc., especially when those takes are being auditioned out of context (ie. solo-ed). (Tip: when recording vocal takes to DAT pan the voice to one side and put a rough mix of the music onto the other. That way you can hear the takes in something like their proper context).

OK; let's say you have recorded onto DAT several takes of the same line of a verse while the sequencer was looping around the relevant two bars. On playback it's obvious that the third take has the best attitude, but a couple of syllables are noticeably out of pitch, and the last phrase is late on the beat. You can either: split the sample up further, retune the duff notes, and re-paste up the original lyric on the sequencer; or use your pitch wheel. The latter is invariably much faster, and is 99% successful in 99% of all cases.

While the vocal sample is looping, start to play with the pitch wheel to see if you can tweak the first out of tune syllable back into pitch on the fly; practise this, then record the pitch bend movement in your sequencer. Now the tuning (or position) can be finely adjusted in the list or grid edit window. (Tip: it is more important to get the timing right than the exact amount of pitch bend, since it is generally easier to alter the event's value than position). Here it makes sense to mask all notes, so that all you can see in the grid are controller events. Try and use the minimum number of events — delete all baggage, as controller info is MIDI's answer to cholesterol.

Now, if you are raising the pitch of a couple of flat notes in this way, it stands to reason that the sample will have been shortened slightly, and that any post-adjustment notes will be early. Fortunately, with vocals this induced error is not often noticeable. Where it is, or where natural timing errors occur, try applying sharp corrective pitch bends in between the words. Again, busk first, record later.

PERFECT BREAKBEATS



With drum loops, it is often the case that by the time beats 1 and 3 are in phase with a sequenced four on the floor 909 kick drum, beats 2 and 4 are flamming or phasing. You could waggle some pitch bend into your sequencer, and time correct on the fly. Better still, construct a one bar Part containing four pitch events, one on each beat. By tweaking each of these around the default value of 64 you can micro-tune the loop between each bass drum. Get the loop edited so that beat 1 is in sync with the kick. Adjust the first event until beat 2 is in sync, then move on to event 2... In this way you can ensure that all four beats are phase correct 'twixt loop and kick. Clever, Eh?

Once the loop has been micro-tuned, it might be worth resampling a time-aligned version of it. You can then delete the pitch events from your loop track, always a good move for the usual reason.

TEMPLATE LIBRARY



Why not start up your 'template library' with a Loop Corrector? A part with a pitch event set to 64 on every beat of a bar is likely to prove useful over and over again. If you use Cubase the template library could be held in the form of an Arrange Window, where controller templates would be available for pasting into any arrangement or song currently under construction. Further uses for controller templates will be discussed below.



"I also find MIDI Volume useful for microtuning dynamics, for example correcting a vocal sample where a syllable is too loud or too quiet. Even de-essing is not out of the question: simply duck the level wherever there is too much sibilance."


MIDI VOLUME



The next most useful controller to have to hand is MIDI Volume (controller #7). Not all keyboards have a slider to generate it, and if yours doesn't you will have to temporarily map your modulation or pitch wheel to it (via the sequencer or sound generator). Cubase offers a controller re-mapping service. (This is one way to get raw controller data on any of the 128 available numbers into your sequencer).

Newer GM keyboards are worth checking out if you want easy instant access to extra controllers: I use an older Roland PC 200, which has four octaves (six 'virtual' ones, via transposition) and dodgy action, but it does offer Volume, Pan and Velocity Sensitivity as well as the usual Pitch Bend and Modulation. (Plus it sits nicely on top of an ST, and weighs not much more than its polystyrene packaging). The latest version offers more.

A MIDI fader box, such as those by JL Cooper, Peavey, or Anatek, would also give instant easy access to several controllers, and would be a good investment for any serious MIDI controllist. (Ouch!)

Now, you might think of MIDI volume as merely a mixing aid, but it is much more than that. I will bypass the obvious level balancing potential, which anyone who has read thus far can work out for themselves. But consider this: how many times have you found that you are short on outboard DSP, or mixing desk aux sends? Some FX, like reverb on a vocal take, really need to be applied in the conventional manner. Reverb applied to a snare, on the other hand, usually gives a repeatable result, and many samplists will resample the snare + reverb in order to free up the processor unit for another task. Unfortunately, this usually means that later on, as the mix develops, the reverb proportion of the combined sample is no longer optimal. In order to reset it, it is necessary to withdraw the reverb unit from its current (new) task and take a new snare + reverb sample. And while the reverb unit is performing this task, the mix is once again incomplete.

The way around this is to sample the reverb only, and to use MIDI volume to mix it onto the dry sample, just as you would if you were turning up an aux. send on your mixer. This technique may be used successfully for just about any single hit, though remember that if you are playing a sequence of several notes the reverb time will shorten as you climb up the keyboard. Even here all is not lost. Take a long reverb sample. Trim it back with your sampler's envelopes, and set the length to remain constant over the keyboard. (Unfortunately, this trick does not work with echoes).

I also find MIDI Volume useful for microtuning dynamics, for example correcting a vocal sample where a syllable is too loud or quiet. Even de-essing is not out of the question: simply duck the level wherever there is too much sibilance. A little painstaking, yes, but effective. Just as we did with pitch information in the previous section, here some raw MIDI volume data should be recorded into your sequencer after a few practise runs, for subsequent fine tuning.

MIDI VOLUME AS MIDI GATE



I mentioned that keeping a 4-in-the-bar pitch template handy was a useful way of quickly time correcting live drum loops. I also have a library of MIDI Volume templates, which I can draw on for special gated effects. The most basic was created by taking a MIDI volume event, placing it on beat 1 of a 4/4 bar, and giving it a value of 127 (full on). I then copied this 16 times in Cubase with a snap value of 1/16th of a bar. I then copied the entire bar, and altered it so that all MIDI volumes were 0. I put the 0 volume and 127 volume Parts onto adjacent Tracks. By retarding (Delay Play Parameter) the zero volume part relative to the full volume part, I created a 16ths variable length MIDI gate, which could be applied to absolutely anything, strings, chords, vocals etc.

I then created composite note on/off parts, with straight 16th gates, and others with variations on the theme. Any desired gate lengths and rhythms can thus be programmed. This is surely what they had in mind when they specified MIDI volume. (PS: I wonder if this is what Sasha has been up to recently?)

OTHER TEMPLATES



Having convinced you (hopefully) of the value of building up a library of pitch and especially volume/gate templates, ready to be copied into any song, why not consider other controller options too? Design your own panning sequences. Try recording edits made on your synth or sampler or effects processor in real time and see what comes out. With practice you should be able to refine some stunning FX sequences. Your friends (and hopefully audience) will be unable to work out how you get your sound. (Unless, of course, they read Sound On Sound).

Many effects units and sound modules can perform a SysEx dump of the current program. Why not hold parts each containing a favourite sound or effect in your template library? (Tip: name everything as you go along; un-named parts in a large library are useless.)

SYNTHESIZER CONTROL



You never know 'til you try. One of the first things I did when I first took delivery of the MC500 (all those years ago) was to record the movement of the sliders of a Juno 106 into it. I still remember the thrill of hearing those real-time shenanigans coming back at me, and being amazed that this capability had been built into such an early MIDI synth — the sliders generated SysEx data, and of course the 106's sound parameters were modified in real time by the data on playback. It subsequently turned out that most MIDI instruments could be edited using SysEx, and this is of course what enables us to use computer-based software editors.

Though software editors are excellent tools, fader boxes such as those I mentioned above can also be handy for editing and synth sounds. Some fader boxes can generate SysEx as well as controller data, and have preset templates for editing popular synths. Even if a fader box can generate only controller data, you can probably map one or more controller numbers to sound parameters, and thereby provide a means of real-time sound control.

CUBASE MIDI MANAGER



This is a clever user-customisable device for recording and editing a large group of controllers from a single window — very powerful, and it can even be used as a synth editor via its SysEx capabilities. It works like this: you are offered a selection of 'Objects'. There is the Fader Object, the Knob Object, the Button Object and so on. I will only consider the Knobs for now (incidentally, Faders are almost identical in operation).

There are three types of knobs on equipment these days. The 'normal' ones start from a value of zero and wind up to a maximum in the clockwise direction (gain). 'Centre detent' knobs increase values from zero in a clockwise direction from the mid point, and do so negatively when rotated counter clockwise (pan, frequency etc.) Either type can be specified within the MIDI Manager. The third type, continuous rotary encoding, cannot, since MIDI controllers always have a fixed range of values (0 to 127).

Objects can be given a controller number (also from 0-127), either manually, or (and this is absolutely excellent), by 'learning' from an incoming controller. MIDI Manager can even 'learn' from incoming SysEx, which can make setting up an editor a whole lot easier (provided you're lucky enough to have a synth that does actually transmit SysEx when you tweak its parameters.)

Prefabricated MIDI Managers are available from Steinberg to legitimate Cubase users for a large and growing number of common instruments and effects. Most new big-sellers are catered for promptly. Recently I've noticed them cropping up in the small ads of SOS, so there must be a growing demand for them — I'm not surprised. Not only do you have simultaneous access to all sound editing parameters, but you can record and edit their movements in real time! Dropping in is possible, in write or update modes (as with desk automation systems). Within the MIDI Manager, however, ultra-precise editing of controller or SysEx events is not possible.



Previous Article in this issue

Rebel Yell


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 - Apr 1993

Donated by: Russ Deval

Feature by Wilf Smarties

Previous article in this issue:

> Rebel Yell

Next article in this issue:

> A Room Of My Own: Nort & Epi...


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