Enhancing Your Roland MT32
By combining plenty of different sounds with the built-in percussion voices and digital reverb, Roland's MT32 multitimbral expander makes the ideal add-on for any sequencer. But it really takes a software editing program to get the very best out of it. Brian Howarth shows you how.
Roland's multitimbral wonder, the MT32, answers the needs of many musicians - particularly those with sequencers - but suffers from offering only preset sounds. However, with a bit of ingenuity and suitable software, there are ways around this. Brian Howarth explains...
Assume now that you have a tune in your head and that you are ready to develop it into a multi-instrumental masterpiece. The first thing you must do to avoid frustration later on is to spend a few minutes planning out the basic instrumentation you would like to use.
The MT32 has 128 preset Timbres on offer as well as 30 Drum/Percussion sounds to choose from. For the sake of discussion, let's say that you will first lay down a basic drum pattern consisting of Bass Drum, Snare Drum and Hi-Hats. As the MT32 comes, the Rhythm part is accessible on MIDI channel 10. This can not be altered from the MT32's front panel, so you must therefore set your sequencer to record on channel 10. Having set the tempo on your sequencer and organised an audible metronome click, you can now record the drum pattern from your keyboard (Note: you will find the corresponding Key/Drum voice listed on page 13 of the MT32 Owner's Manual). You can record the drum part either in one complete take or, if your sequencer allows you to overdub, in several takes until you are happy with it.
Now that you have successfully recorded the Drum/Percussion part, you can proceed to record all the other Instrument parts in your piece, allocating each part to its own MIDI channel. Before doing this, however, a few words about 'multitimbral' as it is applied to the MT32 are in order. Each of the eight Instrument parts, numbered 1 to 8, responds polyphonically to its own independent MIDI channel; from channel 2 to channel 9 respectively. Using the MT32's front panel controls you can assign each part a 'Timbre' (voice) from the 128 ROM presets available. Internally, a Timbre is constructed by using a minimum of one and a maximum of four 'Partials'. The MT32 has a maximum of 32 of these Partials that can be sounding simultaneously. Using the above information in conjunction with the Sound List card (provided with the MT32), it is possible to work out just how complex, in terms of simultaneous notes playing, you can allow your piece to become. To clarify this, let us take the example shown in Figure 1.
Assume our keyboard is set to transmit note data on MIDI channel 2 and we play a chord of D Major. Instrument part 1 on the MT32, which is set to Acou Piano 1, will respond to these three simultaneous notes: D, F# and A. If we now consult our Sound List card, we will see in the top right corner of Timbre 001 that a single note of Acou Piano 1 is comprised of four Partials. Hence, playing the three notes together will use up 12 of the 32 available Partials. Add to this part a bass line on one channel, a string arrangement on another channel and a lead melody line on another channel, and it is easy to see how you can soon use up what would initially seem to be a large number of Partials. The audible results of trying to play more than 32 Partials simultaneously can sound quite odd and unpredictable; you may, for instance, suddenly lose a note out of a chord in, say, a string arrangement or a nicely flowing legato piano section may suddenly become staccato as a drum beat or a bass note 'steals' notes from other MIDI channels.
Clearly then it will quite often be necessary to arrange your instrumental parts in such a way as to avoid 'overflowing' the available Partials. The simplest method of prevention is to use Timbres that require fewer Partials; for instance, you may find that Timbre 003 (Acou Piano 3) sounds acceptable as a piano within the context of your composition. This preset only requires one Partial in contrast to Timbre 001 (Acou Piano 1) which requires four Partials. If a Timbre which only uses one Partial does not sound 'rich' enough, you could try combining it with another instrument part to fatten up the sound. To do this layering, you will have to record or copy your chosen part on to two or more sequencer tracks in order to access the other Instrument parts, which will be on different MIDI channels. You may, for instance, record a Piano part on MIDI channel 2 which uses Timbre 002 (Acou Piano 2). If you then copy this line onto MIDI channel 3, you can set this part to Timbre 003 (Acou Piano 3). You will now have two Instrument parts playing identical lines using only three Partials per note, and the total audible effect may be more pleasing than just a single line using Timbre 001 (Acou Piano 1) which uses four Partials per note.
Using the MT32 as described above can be very rewarding and some stunning productions can be obtained. You can, however, greatly enhance the flexibility and sonic capability of the Roland MT32 by gaining access to the internal configuration of the MT32 via MIDI System Exclusive information.
There are two ways in which you can obtain such access. The first method will require that your sequencer allows you to insert and edit your own MIDI messages, to be transmitted either immediately or at some predetermined section of a song. The second method is to use a software-based Editor/Librarian program - there are several such packages currently available which run on various microcomputers, all of which should provide total access to all of the hitherto inaccessible parameters of the MT32.
To best describe the first method, let us take an example. You have composed and recorded a piece of music which uses a Bass Guitar preset on MIDI channel 2, a Brass preset on channel 3, and Drums/Percussion on channel 10. In order to 'liven up' the Brass sound you have selected quite a large, spacious reverb setting (from the MT32's built-in digital reverb). Unfortunately, this means that the Bass Guitar will also have this large reverb effect on it. Via a System Exclusive message however, you can switch the reverb on or off independently for each Instrument part. To further illustrate this, a System Exclusive message sent to the MT32 to switch the reverb off for Instrument part 1 consists of a string of MIDI data bytes that contain the following information:
Byte 1: F0 Hex (or 240 Decimal). This is the System Exclusive 'Header' byte which identifies subsequent bytes as being part of this 'exclusive message'.
Byte 2: 41 Hex (or 65 Decimal). This is a value which indicates that this particular message is coded in the Roland format and can only be 'understood' by Roland equipment.
Byte 3: DEV. This is the Device ID. In our case it should correspond to the 'Unit Number' of our MT32. This is usually set to 17 Decimal when you switch on the MT32. Because MIDI numbering starts at 0 instead of 1, we must send a value of 16 Decimal to indicate Unit Number 17.
Byte 4: 16 Hex (or 22 Decimal). This is the Model ID which indicates that this message is meant for the MT32 expander and not the D50 synth.
Byte 5: 12 Hex (or 18 Decimal). This is the Command ID which, in this case, indicates that this message contains data as opposed to a request for data.
Bytes 6,7,8: 03 00 06 Hex (or 3, 0, 6 Decimal). These three bytes form the address within the MT32's memory of the particular parameter we wish to alter. In our example you will see that page 9 of the MT32 MIDI Implementation Chart shows that the reverb switch is at offset 00 06 within the 'Patch Temp' area. Page 7 shows us that the Patch Temp area for Instrument part 1 has a base address of 03 00 00. Add together this base address and the offset address and you obtain 03 00 06.
Byte 9: 00 Hex (or 0 Decimal). This is the actual data byte that determines whether the reverb is OFF (00) or ON (01).
Byte 10: 77 Hex (or 119 Decimal). This is the checksum byte which ensures that any errors in transmission of the data will be noticed by the MT32 and the message ignored. To calculate this value, add up the values of the three Address bytes and the Data byte. In our case the sum is 03+00+06+00=09. You now subtract this number from 128 and the result is the checksum value (ie. 128—9=119).
Byte 11: F7 Hex (or 247 Decimal). This byte indicates the end of the System Exclusive message.
If you enter this string of bytes into your MIDI sequencer and then transmit it to the MT32, you will see that you have successfully switched off the reverb effect on the Bass Guitar part.
The above procedure may seem tedious and obscure, but it is a method of altering any parameter that you see listed in the MIDI Implementation Chart and, hence, gaining more control of your MT32.
By far the most pain-free method of controlling the MT32 is by the use of one of the software Editor/Librarian packages that are currently available. Most MT32 Editor packages should allow you to do all the following:
This single feature alone will vastly increase the usefulness of your MT32. You can switch the reverb independently for each Instrument part, use a Pan control to place the sound in the stereo image, and transpose the key of any part. A particularly useful feature is the ability to set two or more parts to the same MIDI channel and then detune each slightly to obtain a much richer sound. This can be a good method of saving Partials by combining Timbres that use only one Partial each to obtain a big sound. You can also select which type of reverb you will use, along with the intensity and overall decay time of that reverb. Another parameter which you can alter for each Instrument part is 'Assign Mode'. This changes the way that available Partials are allocated and can prove quite useful if you are approaching an 'overflow' situation, as described earlier. A full description of the available Assign Modes can be found on page 23 of the MT32 Owner's Manual.
By obtaining access to the actual 'building blocks' of a Timbre you can create your own sounds, either from scratch or by performing small adjustments to a preset Timbre. Spend a little time and effort here and you will find that the sonic potential of LA synthesis is quite amazing. The MT32 Owner's Manual does not, unfortunately, explain LA synthesis in any great detail so it may be worth checking that the software package you are purchasing has some form of tutorial included.
You can obtain an amazing degree of control over the Drum/Percussion section of the MT32. For each MIDI note value from 24 to 87, you can assign a voice with all the following parameters:
TIMBRE: You can select from any of 30 sampled Drum/Percussion sounds or from any of 64 preset or edited Timbres that you have previously placed in the RAM memory bank of the MT32. You can even switch any key off completely!
LEVEL: Each sound within the Rhythm part has its own individual volume control.
PAN: Each sound can be individually placed at one of 15 points across the stereo image.
REVERB: This effect can be independently switched on or off for each sound.
Tip: Before leaving the Rhythm part, here is a useful little trick that you can employ. Assume that you would like the Bass Drum to play at a slightly higher or lower pitch than it is preset to as a Rhythm voice. Using the Edit Timbre section you can select Rhythm 1 as a Timbre to edit, transpose it to your liking using WG Pitch Coarse, and then store it in one of the 64 memory slots. Go back into the Rhythm part editor and select that memory slot as the source Timbre for the Bass Drum note and, hey presto, you have altered the tuning of the Bass Drum!
There are 128 MT32 memories in which you can store a 'Patch'. A Patch can be selected via a MIDI Program Change command and once selected it will in turn select the Timbre, Key Shift, Fine Tune, Bender Range, Assign Mode and Reverb Switch setting that will be used on that MIDI channel.
Having edited all your Timbres to perfection and configured your Instrument parts and Patches for a composition, you will no doubt wish to save these for posterity. A good Librarian section then will be more than welcome, particularly when you consider that the memory of the MT32 is volatile, ie. no edited settings are retained when you switch the power off and they will have to be re-transmitted to the MT32 when you wish to use those settings again.
This last point is worth bearing in mind whatever method you use to control the MT32. In particular, make sure that your sequencer does not send a MIDI 'Reset' command to the MT32 (some sequencers use a 'reset on stop' command) as this will also cause it to return to its default values and 'forget' all your carefully edited settings.
All of the above should illustrate the staggering potential of the Roland MT32 and what makes it all the more attractive is the fact that you can achieve most of your aims with just one MT32 and a sequencer. In most cases, this combination can cost well under a thousand pounds! If you are feeling ambitious and you have a morbid desire to make sure that all 16 MIDI channels are gainfully employed, why not take the plunge and get two MT32's - what a combination!
About the author: Brian Howarth is a musician and freelance software programmer. He wrote the Steinberg MT32 Synthworks editor program for the Atari computer.
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