Phantom Powering Pedal Switcher + GC?

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
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Piplodocus
Posts: 20
Joined: Fri Jul 17, 2009 11:29 am

Phantom Powering Pedal Switcher + GC?

Post by Piplodocus » Fri Nov 29, 2013 6:51 am

Hello Folks!

I was considering buying a VL Pedal Switcher to control my floor pedals. I currently have an old Ground Control (not pro) which I recently got updated to v2.5. From what I gather one button on the GC (or a GCP) will channel switch my MIDI amp, my MIDI rack Fx + whichever combination of the 4 PS loops I want? Assuming so, let's continue...

So currently the Ground Control is phantom powered by my Diezel Herbert (as would work from a GCX). If I get a Pedal Switcher can the Herbert (or a GCX) phantom power the pedal switcher, which phantom powers the GC? I've read the PS can phantom power the GC or a Commander, but not that the GCX (or anything else) can phantom power the PS (and then the GC off that).

If that works, great! Problem solved! If not...

If I can't phantom power the PS then I guess I need to add a Wall-wart and mains plug etc to my pedalboard for the PS. :cry: The only alternative is if I can power it from my VHT/Fryette Valvulator which powers my other pedals. This only has DC outputs though. I'm guessing that although the GC and PS are normally powered from 9V AC, since they have a bridge rectifier in you can power them of 12V DC (9v RMS = roughly 12V Pk). I think this seemed to work with my GC when I tried it once as I don't have the PSU for it. Will this still work over the phantom power to the GC if I power the PS with DC, or is it transformer coupled somewhere so all the voltage will disappear on the phantom power to GC? If all of this does work so far with DC, then how much current does the PS + a phantom powered GC (That's the GC, not GC Pro) draw? For reference how much does a GC Pro draw too if I upgrade to that later?

nyteowl
Posts: 1389
Joined: Mon Jan 25, 2010 8:53 am

Re: Phantom Powering Pedal Switcher + GC?

Post by nyteowl » Sun Dec 01, 2013 6:59 am

It's my understanding that phantom power comes into a Ground Control or Ground Control Pro via the MIDI Out jack, which would be connected to the MIDI In jack of a GCX or Pedal Switcher.

It is also my understanding that phantom power is not commonly shared between MIDI In and MIDI Out jacks on MIDI devices. Therefore, one cannot daisy chain phantom power in the same way one can daisy chain multiple MIDI devices. A GCX or Pedal Switcher will require its own power source in order to provide phantom power to a Ground Control or Ground Control Pro.

However, it is possible for one to open up a MIDI device and solder jumpers between the MIDI In and Out jacks, making phantom power available at both locations. Since a modification such as this requires a certain amount of expertise and would immediately void the product warranty, it is not something I would recommend.
For Sale: Original DMC GCX in Excellent Condition ($275) and a far more versatile SoundSculpture GL also in Excellent Condition ($1750). Free CONUS Shipping.

Piplodocus
Posts: 20
Joined: Fri Jul 17, 2009 11:29 am

Re: Phantom Powering Pedal Switcher + GC?

Post by Piplodocus » Mon Dec 09, 2013 7:05 pm

I gave up and figured I'd use the supplied psu. Only problem is it makes my wah pedal hum loads when mounted nearby to it on the pedalboard. Obviously it's far less ideal and a lot messier having it further away from the pedalboard, but even a foot and a half away it's still making noticeable hum with the wah on. So I'm still very interested whether there's a way I can run it off the DC power already on my pedalboard, else phantom power the pedal switcher and GC from my Diezel's phantom power output. It's gotta be easier than trying to filter the 50 Hz hum with lots of messy (and probably relatively ineffectual) shielding, and it makes the board tidier.

Any more info on phantom power mods?

Piplodocus
Posts: 20
Joined: Fri Jul 17, 2009 11:29 am

Re: Phantom Powering Pedal Switcher + GC?

Post by Piplodocus » Mon Dec 09, 2013 7:12 pm

P.s. The Diezel Herbert manual says the maximum power of the pedal connected to the midi in port cannot exceed 800 mA and the PSU for the pedal switcher (which also phantom powers the GC) is rated at 500 mA output so the Herbie can at least source enough current.

nyteowl
Posts: 1389
Joined: Mon Jan 25, 2010 8:53 am

Re: Phantom Powering Pedal Switcher + GC?

Post by nyteowl » Thu Dec 12, 2013 4:36 am

It's my understanding that certain pedals often work a lot better (e.g., are much quieter) when used with their own dedicated power source. Not that it's an optimal solution, but have you tried running your wah pedal with a separate, isolated power source?
For Sale: Original DMC GCX in Excellent Condition ($275) and a far more versatile SoundSculpture GL also in Excellent Condition ($1750). Free CONUS Shipping.

Piplodocus
Posts: 20
Joined: Fri Jul 17, 2009 11:29 am

Re: Phantom Powering Pedal Switcher + GC?

Post by Piplodocus » Thu Dec 12, 2013 6:01 am

Yes, it is an isolated PSU for the wah. Some wahs (inductors?) don't like being near the mag field of a PSU though. :(

This has developed a lot further since. The answer is yes, you can mod the Pedal switcher to be phantom powered from 12VDC but since the pedal switcher doesn't have a transformer isolated audio output it'll hum like a * unless you have a totally floating isolated phantom power PSU. i.e. the one in the Diezel where negative volts is grounded somewhere inside the amp makes it hum loads. I'm just off to the shop to buy a DC socket so I can drill a hole in the back of my amp and phantom power it with the original isolated ac adapter though...

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