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MIDI Mixing Made Easy

MIDIMation VCA Automation System

Even if your music is fully MIDI-controlled, when it comes to mixing you're probably still relying on fingers and thumbs. But mix automation is coming within reach of the home recordist — MIDIMation offers 16 channels of VCA based level and mute automation for under £1,000. Simon Sanders investigates this new box of mix tricks.



Mixing for today's recording media is an exacting process. The public are forever demanding better production, less noise and more complex stunt-mixing. If you are using a conventional mixer, this means that you need to grow at least four more arms, or find yourself a team of assistant engineers to get it right. Professional studios have had console automation systems for several years now, and for them mix automation is taken almost for granted. However, the smaller studios and home recording enthusiasts have been missing out, due to the cost of automation — over £2,000 for the cheapest 16-channel automated mixing system, until recently. Enter MIDIMation.

MIDIMation is a 16-channel VCA automation system, which is controlled via MIDI. Supplied as a 1U rack unit, the MIDIMation has only one control on the front panel — an on/off switch. Round the back are 16 input/output sockets, (all stereo jacks), and two MIDI sockets, (In and Thru). The unit also comes with a floppy disk, the contents of which we will discuss a little later.

WHAT'S A VCA?



Before looking at the unit itself, let's take a brief look at VCAs and the applications of VCA automation. A VCA, or voltage controlled amplifier, is a circuit which boosts/cuts the level of a signal — an electronic volume control. The amount of boost/cut applied to the signal is determined by the voltage of a controlling signal fed into the VCA, which can come from either a physical controller (eg. a fader on a mixing desk) or from a micro-processor.

The most obvious use of VCA automation is in emulating fader and mute automation with a standard non-automated mixing console. This is achieved by connecting the VCA unit to the mixer's insert points, which allow you to divert the signal coming into a channel to another signal processor — usually a compressor or gate — before passing it through the rest of the desk. The convention is to use 1/4" stereo jacks, wired tip-send and ring-return.

Thus, once the VCA unit is connected across the insert points, the signal levels will be controlled by the VCA settings, independent of the settings on the desk, (although you can still use all of the functions on the channel strip — EQ, aux sends etc. — as normal).

An alternative to using the VCA unit across the insert points is to use it to control the signal levels before they enter the desk. This involves simply plugging the source into the VCA unit, with the VCA output plugged into the mixer. This offers the advantage of leaving the insert points vacant for other uses, although it does mean that, unless you have the VCA I/Os on a patchbay, the unit has to be dedicated to particular sources (not generally a problem in studio situations, where instruments are wired up fairly permanently).

PLUGGING IN



The first task when setting up the MIDIMation is to connect the audio I/Os. If you are connecting it to the insert points on a desk, then you will have to buy (or make up for yourself) a loom of stereo jack leads. For electrical reasons, the MIDIMation sockets have been wired in the opposite fashion to most insert points, therefore the leads need to be connected tip-to-ring and ring-to-tip (ie. cross-coupled). Some desks are wired differently, however, so check your manuals. The only problem with this wiring configuration is that you can't use standard stereo leads — but I always recommend making up your own leads anyway, as it is far cheaper, and you know who to blame if the lead doesn't work.

For other uses, custom leads will have to be made up. For example, to connect a tape machine will require a stereo to two phonos lead. For maximum flexibility, Y-splitters will allow you to use normal leads to and from the unit.

The only other connection to be made is a MIDI lead from the sequencer to the MIDI In. All that remains is to plug in the mains lead and switch everything on.

MIDI CONTROL



MIDIMation works by assigning control of VCA levels to MIDI controller numbers. Each VCA channel is assigned to its corresponding MIDI channel, (VCA channel 1 = MIDI channel 1, and so on). The unit comes with the VCAs set to respond to MIDI controller number 102 and the mutes to controller number 110, and these assignments can be altered by removing the bottom panel to access a block of DIP switches — a table of switch settings is given in the manual. Controller reassignments are only required if you are using more than one MIDIMation unit.

The theory behind this design is that all 16 MIDI channels can still be used as normal, MIDIMation using MIDI Controller numbers that synths do not ordinarily use (as opposed to devoting a precious MIDI channel to MIDIMation with VCA channels assigned to different controller numbers).

WORKING WITH SEQUENCERS



If you are going to use MIDIMation with either Cubase or Notator/Creator, then you will need to use the floppy disk supplied with the unit. This contains a MIDI Manager page for Cubase and an RMG page for Notator/Creator, and use of these is covered in great depth by the manual. If you are already used to using these areas of the sequencers, then you will have no problems, as the set-ups supplied are very well laid out and extremely usable.

For those who are using other sequencers, Too Much Music are working on drivers for other software. Anyhow, if you have a reasonable working knowledge of MIDI, it is not too difficult to set up your own MIDI control system.

I tried out MIDIMation with both Cubase and Notator and encountered no problems at all. The response times were excellent, with no perceivable delays between on-screen action and VCA reaction.

AUDIO PERFORMANCE



Sonically the unit is as transparent as you would expect from a professional piece of equipment, with no thumps or clicks when muting/demuting. I tried desperately to crash the unit, with large amounts of data at impossibly high tempos, but it coped with everything that I threw at it, without a glitch.

I had expected to encounter some zipper noise when changing levels, given the 128-step resolution of MIDI controllers. However, the software within the unit avoids this by smoothing out changes in level.

MIXDOWN



MIDIMation gives us lesser mortals the opportunity to integrate mix automation into our recording systems with the minimum of fuss and bother. The unit is relatively simple to use, although an understanding of how MIDI does its stuff is more than useful.

The use of cross-coupled stereo jacks is a trifle annoying, but it's not as if you will be swapping leads all of the time. Besides, 16 stereo leads do a better job than 32 mono leads at avoiding spaghetti frenzy behind your equipment.

All in all, MIDIMation allows sequencer users, particularly those who run a sequencer in sync with a tape recorder, the luxury of extending MIDI control to the mix at an acceptable price. The only problem is that with the increased use of MIDI control in the studio, the memory capacity of the computer is fast becoming the limiting factor in how far you can go.

FURTHER INFORMATION

£921.20

Too Much Music, (Contact Details).

MIDIMATION SPECIFICATIONS

- Frequency Response: 20Hz-40kHz (+/-1dB)
- Dynamic Range: >110dBv
- THD: <0.02%
- Bandwidth: 8Hz-75kHz
- Crosstalk: <-100dB (@1kHz)
- Shutdown (Mute): >100dB (®1kHz)
- Headroom: +20dBv
- Normal Operating Level: +4dBv
- VCA Resolution: 0.5dB steps


Also featuring gear in this article



Previous Article in this issue

Emu Procussion

Next article in this issue

Still Life


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 - Jul 1991

Gear in this article:

MIDI/Mixer Automation > JL Cooper > MIDIMation

Review by Simon Sanders

Previous article in this issue:

> Emu Procussion

Next article in this issue:

> Still Life


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