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MIDI Matters (Part 3)

Timbre Editing Via MIDI

Jay Chapman leans back and takes a philosophical overview of timbre editing via MIDI.

If you own both a computer and a MIDI equipped synthesizer it is fairly likely that you will use the former to enhance the facilities offered by the latter. One area that most users would like a hand with involves the creation and manipulation of the sounds (or timbres) produced by synthesizers. In other words, we want to edit the multitude of parameters available with a view to creating some sonic masterpiece that will amaze the world and frighten the budgie half to death.

In this MIDI Matters I will discuss some typical limitations of parameter editing using the synthesizer's own facilities (where such editing is possible) and then briefly describe how a parameter editor software program works and what sort of facilities you might expect such a program to offer. In particular, we can get some idea of what the (computer) programmer ought to be doing for us.

There are two main reasons why anyone would produce a parameter editor program.

The first reason is down to sheer necessity! If you buy certain expander modules such as the Yamaha FB-01 or TX7 you will have a number of pre-programmed voices at your disposal but you will be totally unable to create any new timbres yourself. In other words, your synthesizer simply may not provide any voice editing facilities at all.

The second reason is a bit more subtle. Your synthesizer may provide full editing facilities but the access to these facilities maybe limited. Such limitations fall into two areas: input and output.


The old analogue synthesizer days when there was a knob, slider or button to individually control every possible component of the timbre are behind us. This hardware, and the complex front panels, wiring and reliability problems that go with it, are just too expensive. Don't forget that modern synthesizers tend to have far more control parameters than the thirty or forty that might have graced the front panel of the synthesizers of yore.

It is often the case, in fact, that there is but one control to select which parameter is to be edited and another control to change the value of the selected parameter. This can make editing quite a tedious proposition! It can also get very confusing when you forget which of the eight parameters of one of six envelope generators you have already edited, for example.


Some manufacturers, notably Roland, offer users a clever compromise in that if you throw extra money at them they will sell you an extra piece of hardware that has all the knobs, sliders and buttons that they didn't include on the synthesizer front panel in the first place. In this way they keep the price of the original synthesizer competitive while still giving you the chance of buying the easy control option.

For example, if you have already bought a Roland Alpha Juno 1 or 2 you might be interested in the PG300 Programmer. The Super Jupiter requires the MPG80, and the PG800 services both the JX10 and JX8P. You can edit your own voices on all of these synthesizers without the relevant Programmer so it is not a necessary purchase, but it is often a worthwhile one, particularly where live performance is anticipated. One can assume that Roland are getting a good response in terms of people buying Programmers since they will be offering a new one, the PG1000, to mate with their powerful new keyboard, the D50.


When you edit a timbre you need feedback. No, I don't mean that screeching noise! As you change a parameter you want to hear what is going on, which is easy: just play a note on the synthesizer. Visual feedback is also very useful in that it helps you build up your own mental model of how the various components of the synthesizer interconnect and interact to produce the sounds you hear.

It helps even more if you can see the states of related groups of controls all at the same time. Then you can easily proceed logically along the lines of "I'll deal with the oscillator first, then the filter, then the envelope generator..." Without a permanent reminder of the configuration and current state of the controls in front of your eyes, it gets hard to remember what you're doing to which and why!

On many modem synthesizers there is typically only a very small display to give you almost all of the visual feedback you are going to get: one line of 16 characters is hardly adequate when you are trying to figure out matrix modulation on an Oberheim Matrix-6R! The Roland 'hardware' Programmers mentioned above don't just make the parameter input side of things easier of course, they also help in terms of visual feedback.

In recent times both Yamaha and Roland have shown evidence of considering displays a little more carefully. Yamaha have greatly increased the size of the display on the new DX7 Mark II, for example. Roland have implemented a very impressive idea by having an output for an RGB (ie. colour) monitor on their S50 sampling keyboard so that various pages of control information can be displayed. The user will appreciate this facility when trying to effectively loop a sample, amongst other things.

Incidentally, now that Sir Clive Sinclair has brought out his Z88 portable micro (for about £200), which features an 8 line by 100 character display, perhaps we can expect to see such screens built in to synthesizers in the not too distant future!


What can we expect from a Parameter Editor software program running on a micro that is connected to our synthesizer via MIDI?

Firstly, the possibilities are very much governed by the synthesizer itself, which must be able to at least respond to MIDI System Exclusive messages ordering changes in parameter values. Typically the software will ask (via another MIDI message) the synthesizer to dump the current parameter values down into the computer's memory. This information allows the software to build an internal model of the current state of the synthesizer.

Whenever the user edits the parameters for a particular part of the synthesizer, the software can display a screen page showing the current values of all related parameters. Since the computer's screen is available it is possible to show the parameter data in various appropriate forms using graphics and colour to enhance the display, thereby making comprehension much easier for the user.

A decent software package will allow the user to manipulate parameters intuitively rather than forcing him to think in terms of the underlying numeric nature of the parameter values. It might be possible to select a waveform (sine, triangle, sawtooth, square, random) by pointing at drawings of the waveforms on the screen using a 'mouse', joystick or tracker ball, for example. The user might not have to enter a new numeric value even where numbers cannot be avoided: he should simply be able to specify that the value be increased or decreased from the current value until the desired result is obtained.

As a parameter changes, the computer could be set to automatically play a 'test sequence' on the synthesizer so that the timbre being created can be heard in the musical context it will belong to. This is a step towards a fully integrated synthesizer control package.

A common example of lack of effort on the part of the software programmer is when envelopes are presented merely as a string of numeric values. It is far more useful to have the actual envelopes displayed in all their glory. If a mouse (or other 'pointing' device) can be used to move the vertices of the envelopes around the computer screen, then the user need never be aware of the numeric nature of the parameters or even of how many parameters there are!


If the synthesizer has two oscillators, filters and envelope generators per voice with an LFO, then there could well be a configuration display page that shows the interrelationships of these components (Figure 1).

Figure 1

If the user wants to play with the parameters of the LFO or EG1 then he need only point at the relevant blocks on the display (using cursor keys or a mouse perhaps) and new subscreens pop up on the display (Figure 2). The LFO waveforms available are displayed as curves on graphs (see the LFO sub-screen) and are activated simply by selecting the relevant graph. The LFO rate parameter appears as a slider and the rate is changed by selecting the vertical bar of this 'slider' and moving it by moving the pointing device (mouse etc) being used. The vertices of the envelope for EG1 can be 'slid' around the diagram in a similar manner.

Figure 2

Another obvious use of graphics revolves around the editing of any parameters that relate to the keyboard pitch. Why not simply draw a keyboard on the screen and indicate the value of parameters (eg. split points) by positioning relevant graphical information on or about the keyboard already drawn.

Obvious utility functions should be provided. Copying of complete parameter sets from one complex component of the synthesizer to another (similar) component might require no more thought than pointing at a 'Copy' box on the screen and then pointing at the 'from' and 'to' components on a configuration diagram also being displayed on the screen. It may well be the case that the synthesizer in question did not itself have such a facility and the user would have had to copy each parameter manually by first selecting it, reading the value, selecting the new parameter and then inserting the remembered value.


So many computers, so many MIDI interfaces, so many synthesizers... there is no way that I could hope to evaluate and list all of the possible combinations!

The important point here is to look for something more than a piece of software that just transfers the manipulation of the parameter values, in their numeric form, from the synthesizer's display to the computer screen. Intelligent use, by the programmer, of the facilities offered by almost all but the most trivial of microcomputer systems should provide the user with an editor program that uses colour, diagrams, graphics, context, interaction, feedback and so on, to make timbre editing as natural and intuitive as riding a bike - providing you understand the synthesis process, of course.

Last but not least think twice about parameter editor software that crams all two hundred parameters onto one screen display. It may be faster to access any given parameter because you don't have to bring up a new screen display, since all parameters are on the screen all the time. It is likely, however, that you will waste time searching for your parameter among the mass of other information on the screen. Also, in such programs, the use of graphical diagrams will inevitably be restricted to save memory space (and to save the programmer some effort).


If you ever get the chance to look at modern control systems and mimic diagrams in a chemical plant, you will see extensive use of symbols, dynamic diagrams, colour and context because the human operators need every scrap of help they can get in understanding and controlling such a complex operating environment. The software involved costs a lot and does a lot and its creation is definitely oriented towards the user and not the software producer - when you consider purchasing some parameter editor software for your synthesizer, try to be just as discerning. 'Cheapest' doesn't usually mean 'best'!


Read the next part in this series:
MIDI Matters (Part 4)

Previous Article in this issue

When Worlds Collide

Next article in this issue

Sounds of Metropolis

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 1987




MIDI Matters

Part 1 | Part 2 | Part 3 (Viewing) | Part 4

Feature by Jay Chapman

Previous article in this issue:

> When Worlds Collide

Next article in this issue:

> Sounds of Metropolis

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