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Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

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Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby DC-Choppah » Sat Oct 17, 2020 11:29 pm

I need to be able to switch the programs on the Lexicon MX200 from a remote switch at the pedal board.

To do that, I need to add phantom power on the MIDI cable to power the foot switch.

I have this foot switch: http://www.tech21nyc.com/products/effects/midi-mouse/
which connects to the MIDI In of the MX200.

And the Lexicon MX200 is this: https://www.telonics.com/products/proau ... nual_B.pdf

So I want to put DC power on pins 1 and 3 of the 5-pin MIDI connector that goes to the switch.

The goal is to have the footswitch powered by the MIDI cable, so I can do remote program changes. This all works great if I power the switch from 9v. But DC power is limited at the board so I would like to use the MIDI cable for power too.

Any advice is appreciated.
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby Sam Spoons » Sun Oct 18, 2020 10:09 am

I did this with a home built combo which had a 2U rack guitar rig built in (Boss GX700 and Marshall Mosfet power amp) with a breakout cable from the midi plug at the combo end to the midi pedal's PSU, it was a simple job to modify the Boss FC200 internally to connect pins 1 and 3 to the back of the power connector. You could make a midi cable with breakout connectors from both ends if you didn't want to go inside either unit. If you want the Lexicon to power the midi pedal that's a fair bit more complex and probably not something I would want to attempt.
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby DC-Choppah » Sun Oct 18, 2020 8:24 pm

Sam Spoons wrote:I did this with a home built combo which had a 2U rack guitar rig built in (Boss GX700 and Marshall Mosfet power amp) with a breakout cable from the midi plug at the combo end to the midi pedal's PSU, it was a simple job to modify the Boss FC200 internally to connect pins 1 and 3 to the back of the power connector. You could make a midi cable with breakout connectors from both ends if you didn't want to go inside either unit. If you want the Lexicon to power the midi pedal that's a fair bit more complex and probably not something I would want to attempt.

Right. That was exactly what I was trying to decide. Do you modify the Lexicon to put 9v power onto pins 1 an 3? Or do you use a breakout cable and a 9v adapter cut into the MIDI cable?

When I searched for this on the SOS forums, I did find that some folks were recommending to modify the sending box to put 9V power onto the MIDI cable. This would end up nice and clean too. No need for another power adapter.

There is no need for a breakout cable at the footswitch. Just have to add 9V power to pins 1 and 3 back where it plugs into the Lexicon.

But I guess I should make sure that pins 1 and 3 are not connected inside the Lexicon since it may not be happy with 9V on those pins?
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby N i g e l » Sun Oct 18, 2020 9:06 pm

The only thing Ive seen phantom MIDI on was the Rocktron Replitone preamp.

The MIDI in was 7 pin [ is that some kind of standard ?] and was designed to power the Rocktron MIDI floor switch box.

The preamp only took ~1A but the PSU was ~3A a.c.

My main worry about powering a unit from the Lexicon would be putting a strain on the PSU/regulators or introducing noise into the audio.

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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby Sam Spoons » Sun Oct 18, 2020 10:47 pm

DC-Choppah wrote:
Sam Spoons wrote:I did this with a home built combo which had a 2U rack guitar rig built in (Boss GX700 and Marshall Mosfet power amp) with a breakout cable from the midi plug at the combo end to the midi pedal's PSU, it was a simple job to modify the Boss FC200 internally to connect pins 1 and 3 to the back of the power connector. You could make a midi cable with breakout connectors from both ends if you didn't want to go inside either unit. If you want the Lexicon to power the midi pedal that's a fair bit more complex and probably not something I would want to attempt.

Right. That was exactly what I was trying to decide. Do you modify the Lexicon to put 9v power onto pins 1 an 3? Or do you use a breakout cable and a 9v adapter cut into the MIDI cable?

When I searched for this on the SOS forums, I did find that some folks were recommending to modify the sending box to put 9V power onto the MIDI cable. This would end up nice and clean too. No need for another power adapter.

There is no need for a breakout cable at the footswitch. Just have to add 9V power to pins 1 and 3 back where it plugs into the Lexicon.

But I guess I should make sure that pins 1 and 3 are not connected inside the Lexicon since it may not be happy with 9V on those pins?

Yes, if the connections are external I'd avoid the power getting onto the Lexicon. IME pins 1 and 3 are not routinely connected in midi devices (don't take that to be a universal truth), but they are usually connected in the midi cable. I actually made a breakout lead with a male to female 5 pin DIN with only pins 2 & 4 connected to the male which connected to the GX700 preamp/fx unit, the female also had 1 & 3 connected to a coax power connector for the FC-200's PSU. All I needed then was a 'midi' cable with all 5 conductors and the 'spare' pins 1 & 3 supplied DC power.

FWIW I would do the same again if I ever used a similar system (and I do have a couple of Boss VF-1 ½ rack guitar processors and the old FC-200) rather than risk messing with the internals of the processor, the control pedal was pretty simple to modify.
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby N i g e l » Sun Oct 18, 2020 10:59 pm

Sam Spoons wrote: pins 1 and 3 are not routinely connected in midi devices (don't take that to be a universal truth),.

Ive just buzzed out my bought "STAGE LINE" MIDI cables & theres only 3 wires.
I would expect that to be the norm for current day, engineered to a price, cables.

5 pin DIN audio cables should have all wires connected.
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby Sam Spoons » Sun Oct 18, 2020 11:04 pm

You may well be right these days, I bought a few 'midi' cables back in the day and they all had all 5 pins connected, maybe in anticipation of 'midi mk2'?
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby ef37a » Mon Oct 19, 2020 9:24 am

I have no knowledge of the gear involved but would like to make a few observations?

First off, I don't think "Phantom Power" is the correct term here? PP would imply +9V on BOTH pins 1 and 3 ref ground (P2) . I am sure you mean + 9V and zero? Polarity?

Yes, pins 1 and 3 could well be connected to something that would mind 9 volts but most likely O/C or connected to chassis/ground.

Safest way IMHO is a break out box so that the 9V only goes to the the device it is intended for.

How much current is required? "Switching" as a control usually need but micro amps, if a LED is involved a few mA. You want the supply to be S/C proof ('it'appen) so use current limiting resistors.

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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby N i g e l » Mon Oct 19, 2020 9:37 pm

ef37a wrote:
How much current is required? "Switching" as a control usually need but micro amps, if a LED is involved a few mA. You want the supply to be S/C proof ('it'appen) so use current limiting resistors.

Dave


"approx 15mA". It has a 2 1/2 digit LED display with "screen saver mode"
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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby ef37a » Mon Oct 19, 2020 10:35 pm

N i g e l wrote:
ef37a wrote:
How much current is required? "Switching" as a control usually need but micro amps, if a LED is involved a few mA. You want the supply to be S/C proof ('it'appen) so use current limiting resistors.

Dave


"approx 15mA". It has a 2 1/2 digit LED display with "screen saver mode"

That is not an insignificant current so I would use a 12V supply and one of these...https://www.elfadistrelec.pl/en/linear- ... p/17300123

Gives a very clean 9 volts with short circuit protection.

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Re: Adding Phantom Power to MIDI cable from Lexicon MX200 to remote footswitch for program change?

Postby Sam Spoons » Mon Oct 19, 2020 10:55 pm

I just used the unused pins 1 & 3 conductors as an extension from the original PSU...
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