feasibility of controlling a GCX with a Lexicon MPX R1

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dolinja
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Hi all,

I've got a Lexicon MPX R1 foot controller with a GCX on its way (that I'm going to use to rack a bunch of my pedals). However I'm not sure how to connect the two.

The MPX R1 takes a 7 Pin cable (that carries phantom power in the extra two pins). The GCX however is a 5 pin MIDI in, but the manual states that it uses only 3 pins for data and 2 pins for phantom power.

I've used the MPX R1 in the past with a Gmajor, and I have a cable which is 7 pin on one side and 5 pin + an ac adapter on the other side. I suppose I could directly use the 7 pin -> 5 conversion with this, but I'm afraid that the GCX will try and send power down two pins, but not the two that the MPX is expecting, and then the GCX will fry the MPX R1 (the GCX manually specifically warns against this).

Can anyone explain what the correct way to proceed is here?

Thanks!
Jason
 
Ok, a little bit more research and I may have come up with a first cut solution. I could use a regular MIDI cable, but ensuring that only 3 pins (pin 2, 4, 5) are hot, to connect the GCX to the MPX R1. Then I'd need to use the regular power adapter to plug in the MPX R1. Alternatively, I'd continue to use my Rocktron 7 to 5 pin (+ ac) midi cable, enabling me to only run one cable to the MPX R1. In that case, I can't directly connect the 5 pin side to the GCX (because I'm pretty sure that that cable DOES have pins 1 and 3 wired). I would use a MIDI female to female coupler to connect the 5 pin end to a very short 5 pin midi cable that only has pins 2,4,5 wired, which would then go into the GCX.

The explanation for above (as far as I understand from the research): The GCX uses Pins 2, 4 and 5 for MIDI in data, and SENDS phantom power back through pins 1, 3. On the MPX1 side, there is a mismatch. It uses 2,4, 5 to send out MIDI data, it uses pins 1, 3 as midi in for proprietary communications about FX and program selections when connected with an MPX G2 (which I'm not obviously), and accepts phantom power in pins 6 and 7. This means that if I directly connected the GCX to the MPX R1 with the 7 - 5 pin converter, the GCX would send power down pins 1 and 3 where the MPX R1 is looking for MIDI in signals there, and would fry. Thus I need to use the unwired 1,3 pin cable out of the GCX to make sure it's power doesn't go anywhere, then through the female-female coupler I could go into the Rocktron 7 pin to 5 pin cable.

What would really be the coolest solution would be to enable the GCX's phantom power to power the MPX R1. Then I'd need a custom type of MIDI cable where on one end there'd by a 5 pin connector and on the other a 7 pin connector. Pins 2,4,5 would be connected normally, but the power being sent down pins 1 and 3 through the cable would have to come out of pins 6 and 7 on the 7 pin end. As far as I know nothing like this exists, has anyone ever made one? I have zero soldering skills right now, but this could be a fun project.

Any ideas about any of this? Could someone validate my thinking? I'm rather new to this and haven't tried anything yet.

Regards,
Jason
 
What you're asking is fairly complex and requires extensive knowledge of both units. I'd keep this over at HRI as I feel you'll be getting better responses there than you'd ever get here.
 
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