I'm getting a Digitech Sdrum for live looping. I would like to MIDI sync the Sdrum with a Boss RC-300 looper. The Sdrum can only be a MIDI master, not a MIDI slave.
In order to slave the RC-300 to the Sdrum I need a way to send MIDI message CC#64 with a value of 127 from the direction of the Sdrum to the RC-300.
How do I do this?
The Harman Canada Engineers who developed the SDRUM also clandestinely included the ability to sync MIDI devices to the SDRUM via the JamSync connector. The SDRUM must be the master since it only sends these MIDI commands. This is not considered an official feature since it was initially included for internal use/testing/future dev only. It requires a custom cable to be made that follows the wiring below:
If you don't want to make a custom cable then Eureka Sound will make one for you.
Next you need to convert the Midi Clock signal from the cable to MIDI CC#64 with a value of 127.
To do this, get a MIDI message conversion box such as the Midi Solutions Beat Converter. This is powered from the MIDI line and the SDRUM may not have sufficient current so you may also need the MIDI Solutions Power Adapter. If you don't have the means to send MIDI SysEx messages from your DAW or keyboard then see How do I send arbitrary MIDI SysEx messages from a Windows laptop to a MIDI device?
On the BOSS RC-300, go into Memory Edit | Assign Controllers. Find an unassigned controller, like 8. Set it to ON, Target to MEM Tempo (tap), and Source to CC#64. Don't use this to trigger the Rhythm Track or it will restart on every beat.
In my google search, it appears that the Sdrum doesn't have any functionality to support this or any MIDI functionality at all. There is no MIDI output and the USB port appears to be used just to update the firmware. If I understand the functionality of the Sdrum, you may be able to just have the output of your looper go into the Sdrum and it will play an accompanying beat for it, following the timing of the loop. I've done a good amount of stuff with looping and can say that there are issues, mainly with starting and ending the loop in perfect time, so there may be issues with the Sdrum being able to sync up properly with the loop if your loop isn't in pretty good time. But it does seem like the Sdrum is designed to work with a human (ie, not perfect time), which would presumably mean that it could compensate for a less than perfect loop. You might also try going from your guitar/bass through the Sdrum and into the looper, then disengaging the Sdrum. I suspect that this could be more difficult, since the Sdrum wouldn't be able to attempt to compensate for the loop length.
Unfortunately it doesn't seem to me that this is possible (or at least, it's going to be very difficult). Although the post found by filo01 shows a way to send MIDI Start, Stop, and clock from the SDrum, The RC-300 manual (page 41) states:
The RC-300 will not receive MIDI clock or MIDI start/stop data from an external device. (The RC-300 cannot synchronize as the slave.)
(This is despite the fact that it seems possible to sync one RC-300 to another - this may be done through system exclusive messages).
You say:
In order to slave the RC-300 to the Sdrum I need a way to send a MIDI CC#1-31 or CC#64-95 message
...but the manual - (page 23) only talks about being able to assign those as a way to start/stop the unit, they don't talk about keeping it in sync - and in any case, the SDrum isn't able to send those CC messages.
Unless you have information beyond this, I'd suggest using bits of gear that are supposed to be compatible with each other.
