Stacking Midi Devices

Q & A for building and interfacing your rack gear with Ground Control Pro and GCX-based systems.
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Pacomgl
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Location: Ohio

Stacking Midi Devices

Post by Pacomgl » Wed Mar 06, 2019 4:13 pm

My current rig consists of a GCX, Ground Control Pro, G Major 2 and a Whammy DT. My Midi map is:

GCX Midi In - G Major 2 Midi Out
GCX Midi Out - Whammy DT Midi In
GCX Pedal Out - Ground Control Pro

I recently purchased an Electro Harmonix Mod Rex and unsure on where I plug the “Midi In” from?

The GMajor has a “Midi Thru” if I use that, do I have to do all my setup on the GMajor for the Mod Rex as opposed to the GCP?
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nyteowl
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Re: Stacking Midi Devices

Post by nyteowl » Thu Mar 07, 2019 5:25 am


You must have an older model GCX, as the newer models do not have the connectors you listed. Instead, they have MIDI Out, Pedal In, and Power connectors, so as described your MIDI Map is somewhat confusing.

In any event, I suspect it is safe to presume however you have your gear connected has been working so far, so to answer your question, the G-Major's MIDI Thru connector simply passes on MIDI information that has entered the GMajor through its MIDI In connector without altering it in any way, so you would not have to do anything on the G-Major to set up the Mod Rex. Everything would be done on your GCPro, with the corresponding parameters configured on the Mod Rex.

Hope this helps.

I am not affiliated with Voodoo Lab in any way, but enjoy sharing what little MIDI and signal routing knowledge I've picked up over the years. If you find my assistance helpful, please pay it forward.

Pacomgl
Posts: 9
Joined: Thu Jun 04, 2015 7:20 am
Location: Ohio

Re: Stacking Midi Devices

Post by Pacomgl » Thu Mar 07, 2019 8:42 am

I’m trying to go off memory, so I may have mislabeled something. My rig is at our rehearsal space.
I’m happy to hear I can do my programming on my GCP for the Mod Rex. Thank you for the information.
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JohnClark
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Re: Stacking Midi Devices

Post by JohnClark » Fri Mar 08, 2019 12:04 pm

There is a small problem here in that the Whammy DT and the Mod Rex each only have a MIDI Input jack, but no MIDI Output/Thru jacks. In order to run both of these in the same rig you will need a MIDI Splitter of some sort.

Your MIDI Chain would look like this:

1. Ground Control Pro MIDI Out to GCX Pedal IN.
2. GCX MIDI Out to G Major 2 MIDI In.
3. G Major 2 MIDI Thru to MIDI Splitter MIDI In.
4. MIDI Splitter MIDI Out/Thru 1 to Whammy DT MIDI In.
5. MIDI Splitter MIDI Out/Thru 2 to Mod Rex MIDI In.

The MIDI Solutions Thru would work for this.

I hope that helps!
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nyteowl
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Re: Stacking Midi Devices

Post by nyteowl » Tue Mar 12, 2019 3:17 am

JohnClark wrote:
Fri Mar 08, 2019 12:04 pm
There is a small problem here in that the Whammy DT and the Mod Rex each only have a MIDI Input jack, but no MIDI Output/Thru jacks. In order to run both of these in the same rig you will need a MIDI Splitter of some sort.

Your MIDI Chain would look like this:

1. Ground Control Pro MIDI Out to GCX Pedal IN.
2. GCX MIDI Out to G Major 2 MIDI In.
3. G Major 2 MIDI Thru to MIDI Splitter MIDI In.
4. MIDI Splitter MIDI Out/Thru 1 to Whammy DT MIDI In.
5. MIDI Splitter MIDI Out/Thru 2 to Mod Rex MIDI In.

The MIDI Solutions Thru would work for this.

I hope that helps!
Since the G-Major 2 has both a MIDI Out and a MIDI Thru jack, could he not use them instead of purchasing a splitter by connecting the G-Major MIDI Out jack to, say, the Mod Rex and the G-Major MIDI Thru jack to the Whammy DT?
I am not affiliated with Voodoo Lab in any way, but enjoy sharing what little MIDI and signal routing knowledge I've picked up over the years. If you find my assistance helpful, please pay it forward.

JohnClark
Posts: 7399
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Stacking Midi Devices

Post by JohnClark » Tue Mar 12, 2019 1:29 pm

nyteowl wrote:
Tue Mar 12, 2019 3:17 am
Since the G-Major 2 has both a MIDI Out and a MIDI Thru jack, could he not use them instead of purchasing a splitter by connecting the G-Major MIDI Out jack to, say, the Mod Rex and the G-Major MIDI Thru jack to the Whammy DT?
The MIDI Out will only transmit MIDI Messages generated by the G-Major 2 itself. It will "eat" any messages that would have otherwise been intended for downstream devices. One would have to program each G-Major Preset to generate a MIDI Program Change. ...and its limitation may be that it will only do that on the same MIDI Channel it is set to Receive on anyway. So relying on it to control multiple devices would be burdensome in that you would be right back to the old game of MIDI Mapping.

Using the Thru and a splitter keeps the original intention of all preset programming done on the Ground Control Pro and still allows independent control of each device in the MIDI path. The MIDI Thru will allow all the data seen at the MIDI In to reach the downstream MIDI devices. The downstream devices in turn will respond to only the messages on their assigned MIDI Channel and ignore the rest of the data.

TC followed the rules of these jacks per the MIDI Spec true definitions. It's the rest of us that sometimes deviate that end up making things confusing. ;) For Instance our GCX has a "MIDI Out" but it doesn't actually truly follow the definition of either a MIDI Out nor a MIDI Thru. To be honest, it most closely fits the description of a Thru, where it mirrors everything seen on the IN, except the GCX will filter out the messages intended for itself.
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nyteowl
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Re: Stacking Midi Devices

Post by nyteowl » Thu Mar 14, 2019 5:33 am

Thanks for the clarification, John!!
I am not affiliated with Voodoo Lab in any way, but enjoy sharing what little MIDI and signal routing knowledge I've picked up over the years. If you find my assistance helpful, please pay it forward.

Pacomgl
Posts: 9
Joined: Thu Jun 04, 2015 7:20 am
Location: Ohio

Re: Stacking Midi Devices

Post by Pacomgl » Sun Mar 17, 2019 8:34 am

Thanks for all the input, I am most definitely going:
GCP Midi Out > GCX Pedal In
GCX Midi Out > G•Major 2 Midi In
G•Major 2 Midi Thru > Whammy DT


Those Y cable splitters work just fine right?
Of course I may add another midi device down the road (although I can’t seem to fathom why at this point) so I could just get a midi quad to be safe.
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