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Tonelab LE - Second expression pedal via MIDI - primer


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Maybe this is answering a question that only I asked, but I figured out how to set up a second expression pedal for the Tonelab LE, using a MIDI Pedal Controller from MIDI Solutions and a "normal" Roland EV-5 analog expression pedal. Physically, you connect the expression pedal to the MIDI Solutions controller, then connect the controller to the TLLE using MIDI in/out cables. This part is easy.


The REAL trick is in programming the MIDI unit, and in interpreting the almost incomprehensible MIDI implementation chart for the TLLE that Vox publishes on their website.


You have to program the MIDI Solutions Pedal Controller, because out of the box it doesn't know what you want it to do. It seems odd that MIDI Solutions doesn't have software to allow users to do this - they refer you to a different site, to get shareware called Bome's Send SX. It's free, and it's pretty easy to understand, just odd they don't have their own. Instructions for programming the MIDI unit are fairly clear. The hex programming string I ended up with was this. I show it in 2 lines, because the first line is the programming of the MIDI Solutions controller unit itself, the second line is the System Exclusive command that I'm programming the MIDI Solutions box to send to the TLLE - in other words, the second line is what the TLLE "hears".


Part I (This is the MIDI Solutions programming line):

F0 00 00 50 16 01 03 0A 00 64 F7


Part II (This is the SysEx command the TLLE "hears"):

F0 42 30 6D 10 41 08 05 00 00 F7


The first five bytes of Part I don't change. The seventh byte ("03") tells the unit you're sending a System Exclusive command. The next byte ("OA") is the trickiest - it tells the MIDI unit WHICH BYTE OF THE SYS EX COMMAND WILL CHANGE WHEN YOU CHANGE THE PEDAL POSITION!


Part II is the actual SysEx command that gets sent to the TLLE. Reading the MIDI Implementation document was rather difficult, and I think Vox drafted it deliberately to make it harder than it needs to be. (Probably just paranoia here). The first five hex bytes identify the command as a SysEx command being sent to the TLLE on MIDI Channel 1. The sixth byte ("41") indicates you are sending a Parameter Change instruction. The seventh and eighth bytes ("08" and "05") tell the TLLE you are changing the Channel Volume. The ninth and tenth bytes ("00" and "00") are the actual values - you see zeros here, but the actual value sent for the tenth byte is the one that is being changed by the Roland EV-5 pedal position. Remember Part I of the command string? That byte "0A" is just the way you write "the tenth byte" using hexadecimal. Note that I'm altering the 10th byte, not the ninth byte - both of them represent the Channel Volume value, but only the tenth one gets used - the reason is beyond the scope of this already too-long message.


Later today, I'm going to try setting it up to alter the VR volume instead of the Channel Volume - all it should take is to change the SysEx command to address VR volume instead, so that part should be easy.


I know this is probably not something many people will care about, but I beat my brain against it for a week, so if anyone else can benefit from this it would make my day.


Tom Hyzy

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