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Lexicon MRC

MIDI Remote Controller

Article from Sound On Sound, March 1989

Lexicon's MRC unit is much more than a fancy remote controller for their PCM70 and LXP1 signal processors - it also provides analogue-like controls for easy editing of DX synth parameters and manipulation of virtually any MIDI controller data. Martin Russ checks out the power behind the buttons.

The secret of making things happen to your precise wishes is control. Effective control is what you need if you are to succeed in any enterprise - especially when using MIDI.

Controlling notes is easy, and some very good controllers already exist: the keyboard from a piano; the fretboard from a guitar; the keys on a saxophone; and the sticks of a drummer. Unfortunately, none of these is very good at controlling MIDI - not in the sense of enabling the conversion of pitch information to MIDI note messages, but in the wider meaning of a general purpose manipulator.

Most of us are guilty of thinking of MIDI only in terms of notes, velocity, program changes and pitch bends. The very nature of keyboard instruments makes velocity control easy and flexible but makes the bending of individual notes in a guitar-like way difficult. Equally, the envelope control possible with any blown instrument makes synthesizer envelope generators look very inadequate. Each instrument tends to impose its own style upon the notes and methods of expression - this is often one of the major reasons why keyboard synthesizers and samplers always seem to sound subtly different to a 'real performance'.

So what would a general purpose MIDI controller look like? A computer program with a suitable interface would be one solution, but the computing power of modern personal computers is probably better spent on sequencing or sample editing. No, a specialised piece of hardware is required, with the ability to produce a wide range of MIDI messages, and equipped with several ways to control and manipulate the large variety of possible MIDI Controllers such as footpedals, breath controllers, footswitches, data entry sliders, etc. In fact, such a device would probably look very like the Lexicon MRC.


I wish there were another word for controller - 'manager' comes closest to a sensible alternative. The confusion lies in the way MIDI jargon calls anything which can be used to produce expression a 'Controller', whilst at the same time any device which directs such things should also logically be called a 'controller'. Lexicon call their manager of MIDI Controllers a MIDI Remote Controller (MRC), and so I shall refer to it as such. The 'remote' part of the name stems from the intended main function of the MRC, which is to act as a remote control device for their PCM70 and LXP1 signal processors (reviewed SOS Dec 87, Oct 88 respectively). Lexicon are noted for the technical excellence and wide functionality of their products, and so the MRC is rather more than just another remote box to have lying around the mixing desk.

The PCM70 and LXP1 really ought to be in larger boxes! I say this because their front panels hide the huge potential for manipulating and processing sound - the size really is deceptive. The PCM70 in particular repays long and careful attention - especially to using MIDI messages to control effects parameters, or 'Dynamic MIDI' as Lexicon call it.

As with any small enclosure, there is a physical limit to how many controls you can reasonably put on the front panel, and so the MRC is designed to provide access to many of the most useful commands at once - very much in the same vein as the PG1000 programmer for the Roland D50 synth. For the LXP1, where the only parameters directly accessible from the front panel are delay and decay, the MRC provides access to eight extra parameters, which are not readily addressable except via System Exclusive messages; so the MRC really does extend the creative potential of these processors enormously.


The Lexicon MRC provides 10 basic devices for controlling things: four sliders, four pushbutton switches, and two pedal/footswitch 'external' inputs. Additionally, MIDI Program Change messages can be transmitted easily using a dedicated front panel button.

When used as a dedicated remote controller, the sliders are assigned to various control parameters within the Lexicon LXP1 and PCM70, and the switches and pedals are disabled. Now four sliders are not really adequate for precise control over complex reverberation treatments and digital effects, and so the MRC provides a 'Page' button which permits you to assign a different set of parameters to the sliders on each page and to quickly call them up. There are two pages (eight sliders' worth) for the LXP1 and three pages (12 sliders' worth) for the PCM70. The backlit 2x24 character blue LCD window in the MRC shows the value of the assigned parameter and an abbreviated name for each page. Careful design makes the MRC feel like a dedicated controller for the PCM70 or the LXP1, and it seems to do a very effective job for both.


Not content with this, Lexicon have made it possible for the MRC to act also as a controller for 6-Operator FM synthesizers (DX7, TX802 etc). Four pages of sliders provide 15 controls designed to make FM programming more accessible, and they provide easy ways of editing DX sounds with macros for Brightness, Waveshape, Emphasis and others, as well as Volume and Timbre Envelopes (as implemented on the new Yamaha YS100 and YS200 synths). In many ways these controls are similar in intent to those on my 'Artificial Intelligence Editor for the DX7' program for the Atari ST (reviewed SOS April 88 - a demo version is available from SOS Shareware). Having several sliders available at once makes the tweaking of FM sounds much easier, and I had no difficulty making some very effective edits to synth sounds.

This FM application gives some hints to the final mode of operation of the Lexicon MRC - Generic MIDI. This mode enables the sliders, switches and pedal controls to be used to alter almost any MIDI Controller. Unlike the previous modes, where the pages selected the function of the four sliders and displayed their values, in Generic MIDI mode the 'Page' button merely selects which values are displayed - thus all 10 user controls are available simultaneously! Now this really does sound useful in a MIDI system - it can provide a single central controller for both small and large MIDI networks.

The MRC enables links to be made between sources - any of the 10 user controls and a wide range of destinations (mostly MIDI Controllers), but certain other useful MIDI messages such as drum machine Start, Stop and Continue commands can also be sent, even incrementing Program Changes. The sources and destinations are outlined in a separate side panel.

With such a range of user controls and things to be controlled, you won't be surprised to learn that there are many possible ways to use the MRC. I have included some of the applications I used it for whilst testing it out, as well as a few other ideas, in another side panel.


So much for what the MRC can do, how does it do it? Lexicon have arranged the MRC in a familiar format to synthesists: you have 10 performance memories which can be used to store your personal favourites from a selection of 32 LXP1 setups, 32 PCM70 setups, 32 DX/TX setups, and 10 Generic MIDI setups. Lexicon call these memories 'Machines'. Setups may be edited, so you can use them to store your own effects or Generic MIDI controls - the Machines are really for rapid access to your favourite setups.

When using the MRC as a remote controller, choosing a Machine is as easy as you could hope for - you press the 'Machine' button and use either the leftmost slider or the numeric keypad to select one of the 10 ('0' on the keypad counts as 10) named available Machines. To access the selected Machine you then press the large 'Enter' button and the Machine will become active. Pressing the 'Setup' button lets you scroll through the named setups with either the leftmost slider or the keypad, and hitting 'Enter' activates it. Changing setup is just a matter of pressing 'Setup', then scrolling or keying in a new number and pressing 'Enter'. In fact, selecting a new Machine involves just pressing the 'Machine' button and selecting as well. For something as complicated as the MRC, this really does seem to be too simple! Even the MIDI connection - a single MIDI lead from the MRC Out to the peripheral's In - is easy to make.

In fact, this apparent simplicity is mostly due to clever use of MIDI; when you select a setup, the MRC sends the appropriate information to the LXP1 or PCM70 so that both units are working on common information. For the DX/TX editing mode you also need to have a MIDI cable connected from the synthesizer's MIDI Out to the MRC's In, so that the details of the FM voice can be transferred. Once done, you can mostly forget about repatching MIDI cables - the MIDI Ins are merged with the MRC so that the incoming data and the MRC's own data both emerge from the same MIDI Out socket. I ought to mention that the MRC has two Ins and two Outs, so you do not need to buy a Thru box in order to control two other MIDI devices.

Having called up a setup, you use the 'Page' button to cycle the display through the available pages, accessing a different set of parameters for the four sliders. A neat ergonomic touch is hidden in the 'Page' button - if you hold it down the display shows the machine type (LXP1, PCM70, DX/TX or Generic MIDI), the current setup description, and the current page number. Also showing considerable thought is the ability to 'latch' the sliders. Here you can choose to have the sliders continuously active or only active when they pass beyond the displayed value, rather like a peak-hold function on a meter except that it works in both directions, since once beyond the value it tracks the slider until you change to another page. Lexicon call this 'slider nulling', and the control for it is hidden away in the System Parameters...

The System Parameters are the global controls for all the machines and setups. They enable the user to tailor the MRC to their own preferences — the slider nulling on/off control is one example. The status of other controls like memory protect on/off, merge on/off, System Exclusive channel number, MIDI bulk dumps and Program Change increment on/off can also be determined.

The Generic MIDI setups are not difficult to use, its just that there are so many possibilities. The MRC comes with a few general purpose setups designed to show you a few of the applications, but the control I reached for was the 'Edit' button. As you might expect, editing consists of selecting sources and destinations, and defining how they interact. The leftmost slider selects the source, the next slider the destination, and any parameters continue to the right - on other pages if necessary.

For example, selecting a Continuous MIDI Controller as a destination from a slider lets you allocate the MIDI channel number, which of the two outputs to use, and set the high and low points of the slider range, as well as the slope (linear, logarithmic or anti-logarithmic). You can set the high and low points in reverse so that the slider works from top to bottom if you so wish. Once set, you can give the user control its very own four character name, which will appear in the LCD window whenever the relevant page is selected. The switches and pedal sources have much the same structure.

When you are setting up a remote controller for MIDI in this way, it is really useful to be able to see the effect as you edit it. With this in mind, the '*' button on the keypad lets you quickly try out the effects of edits without having to run a machine and setup - it really is refreshing to find a product like this which anticipates so many of your needs! In much the same way, the 'Program' button lets you send Program Change messages whilst in any machine (except when editing) and returns you to the machine as soon as the message has been sent - you might have expected a separate machine for Program Changes, but this is much more convenient.


The other aspect of how the MRC does what it does is hidden inside the case, and it is here that we see a timely use of an often forgotten aspect of electronic design - the use of appropriate technology. Instead of a 16-bit microcontroller chip and custom designed chip to do all the MIDI processing, the Lexicon MRC uses a Zilog Z80 - an 8-bit microprocessor running at 4MHz. Since MIDI comes in 8-bit bytes anyway, this really is quite a sensible choice. The Z80 is low-cost, widely available, easy to programme, well supported, available from a large number of manufacturers, and it can do the job! Peripheral circuitry includes 16K of battery-backed static CMOS RAM, and 24K of EPROM-based operating system software.

All the electronics apart from the display, switches and sliders (which are mounted in the top of the case) are mounted on a single, high quality, double-sided, plated through hole Printed Circuit Board. Nice touches like the quality control stickers on the EPROMs and the Microprocessor chip give the impression that this is a product which is not going to fall over the first time you use it seriously. The mains power supply is external to the MRC, and the mains on/off switch is a pushbutton on the rear panel sandwiched between the LCD contrast control and the power supply input socket.

Lexicon provide a 96-page A5 user's manual which also provides guidance on using the MRC, useful hints and tips, and MIDI System Exclusive details. No problems here - in fact, I could find very little to criticise at all in the MRC (see 'Suggestions' panel).


The Lexicon MIDI Remote Controller is exactly what it says it is - a software definable, remote controller and programmer for signal processors, synthesizers and all other MIDI equipment.

The predefined setups for particular peripherals like the Lexicon PCM70 and LXP1 signal processors greatly enhance the usability of those products by providing convenient and simultaneous control of multiple effect parameters, whilst the FM editing mode allows FM-phobics to customise DX sounds without any need for detailed knowledge of 6-Operator DX and TX synthesizers. Best of all, the Generic MIDI mode lets you control any MIDI equipment which uses MIDI Controllers for accessing its internal parameters, as well as providing a means to control large instrument setups without recourse to a computer.

Some products have an obvious end application, others become more useful the more you explore their possibilities — the MRC has immediate purpose as a remote control for the LXP1 and PCM70, but also has longer term potential as a comprehensive MIDI Controller. No other stand-alone controller that I know of has the same mix of features - a few master keyboards offer similar functions, but most people seem to prefer using their favourite synth as master controller, and the MRC would complement this approach nicely.

The MRC should certainly repay careful investigation, and I have no hesitation in recommending it for all users of LXP1s, PCM70s and everyone else who wants to use MIDI effectively. When we reviewed the LXP1, this magazine called it a 'first-rate instrument'; so the MRC must definitely qualify for being called a 'first-rate controller'!


£325.25 inc VAT.

Stirling Audio Systems, (Contact Details).


By assigning the MRC's four pushbuttons to Start, Stop, the Note Number of your favourite drum sound, and to Volume (low = 0, high = 127) respectively, you have got yourself a nice drum machine controller that will let you hide the drum box away in a corner and run it remotely. Setting the fourth slider to control MIDI Volume as well gives you a reverse 'Mute' control via the button (the drums only play when you hold the button) with volume control on the slider to override the muting. To invert the button's effect, just set low to 127 and high to 0 - now the button acts as a normal mute.

Pedals make great controllers for certain parameters, but switches can also be pressed into action usefully: setting a switch to bring in a preset level of modulation, for example. In order to use ordinary switches with the MRC, you need to make them function like pedals. To achieve this, take a mono jack socket and a stereo plug and make an adaptor that looks like this:

This joins the ring and tip together, enabling you to use the switch for pitch bend (instant octaves or fifths), preset volume changes or accents (use low = 100 approx and high = 127) as well as any switch-based functions. Just insert the jack plug from the switch into the mono socket and the stereo plug into the MRC pedal/external input.

Assign the sliders to control MIDI Volume on the channels appropriate to your equipment and, hey presto, you have a four channel submixer disguised as a remote controller!

Create your own LXP1 effects - the MRC expands the possibilities by providing extra parameters to play with. You also get another 16 presets stored in the setups of the MRC.

By deliberately disconnecting the DX synthesizer from the MRC's MIDI In after sending a voice for editing and then changing voice, or by changing the algorithm from the DX's editing functions, it is possible to confuse the MRC. This can produce both amazing and useless editing functions, depending upon the context of the voice. Similar explorations can be made with the PCM70 and LXP1 by changing algorithm selections from their front panels, although Lexicon do remind you in the manual that you will probably be altering parameters with no relevance to the current effect.


  • 4 sliders
  • 4 switches/buttons
  • 2 external pedals/switches
  • Program change (accesses the chosen setup)


The Destination names are Lexicon's own, but they correspond closely to the official MIDI Specification 1.0 Controller numbers (shown in parentheses where appropriate).
  • None (useful for 'safe' setups)
  • Pitch Bend
  • Controller 0
  • Modulation Wheel (1)
  • Breath Controller (2)
  • Controller 3
  • Foot Pedal (4)
  • Portamento (5)
  • Data Entry (6)
  • Volume (7)
  • Controllers 8 to 31
  • Sustain Switch (64)
  • Portamento Switch (65)
  • Sostenuto Switch (66)
  • Soft Switch (67)
  • Switches 68 to 95
  • Note On (velocity from 0-127)
  • Program Change
  • Start
  • Stop
  • Continue
  • Song Select

NOTE: Some Destinations are not available for some Sources, eg. Start cannot be controlled by a slider or external pedal. Notice also that aftertouch is not available as a controller. Many synthesizers and expanders use this for controlling filter cutoff, pitch bend, modulation etc. Check the MIDI Implementation chart of your instruments to see if these parameters are also mapped to suitable MIDI Controller numbers.


Here are a few suggestions that would make the MRC even better than it already is:

Implement Aftertouch (channel pressure) as an extra Destination.

How about enabling 'at first silly but potentially very useful' things like assigning Song Select or Program Change to a slider or pedal?

Increase the number of Generic MIDI setup memories.

Add some type of stand to allow the MRC to be propped up at an angle.

Make the slider knobs stand out slightly more from the recesses in the front panel.


If your master keyboard does not support a goodly range of MIDI Controllers, then the Lexicon MRC represents a very comprehensive route to providing sophisticated control over your MIDI network. Unlike a home computer, the MRC is well suited to live performance work, and the instant recall of complete controller setups could be just what complex live sets have been waiting for. In the studio, the MRC will probably outlive most of the instruments it will be controlling.

The MRC's System Exclusive usage is confined to bulk dumps and the DX/TX voice request and parameter editing functions.

Aftertouch (key or channel pressure) is not recognised or transmitted - you cannot use this as a Source or Destination controller - a pity! Similarly, incoming MIDI Controllers are not recognised and so cannot be altered by the MRC, and MIDI Clock is not recognised or transmitted - it would be nice to have control of this in the same box as all the other MIDI controls.

MIDI In data can be merged at the Out socket, so although the MRC does not alter Controller messages, it will still transmit them as if it was a Thru box. This means you can insert the MRC between a master keyboard and an expander and be able to use pitch bend and any other Controllers on your master keyboard in addition to those you set up on the MRC.

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Audix Microphones

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Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

The current copyright owner/s of this content may differ from the originally published copyright notice.
More details on copyright ownership...


Sound On Sound - Mar 1989

Donated & scanned by: Mike Gorman

Gear in this article:

Remote Control > Lexicon > MRC

Review by Martin Russ

Previous article in this issue:

> Audix Microphones

Next article in this issue:

> Finale

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