Splitting USB midi into 2 ?

So here's the situation. My keyboard rig is a USB controller keyboard running Mainstage 3 on a Macbook Pro. For redundancy I want the USB midi from the controller keyboard to go to 2 identical Macbook Pro's both running exactly the same concerts in Mainstage. Then if there's any issue with one Macbook it won't make a difference to the show. As these are to be used for ticketed theatre gigs I can't afford any issues or have time for a reboot etc ... I need to be covered 

So anyone have an idea of the best way to do this ?
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  • KittyfriskKittyfrisk Frets: 6516
    edited July 20
    If you don't know how to do it, I don't know who will 
    Anyway I had a look & found a couple of sites that might be of help (or not).
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  • RolandRoland Frets: 5452
    Would a USB splitter cable suffice?
    Known here as Old Misery Guts or the Big Bad Classified's Sheriff. Also guitarist with  https://www.undercoversband.com/.
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  • urban_winterurban_winter Frets: 64
    I am annoyed that I can't immediately see how to do this. I think I must be missing something obvious.

    The problem is that USB is designed to have one host and one or many devices. You want to have two hosts and one device. I don't think any passive device or hub can do this. It would be possible to build what you need with a microcontroller or raspberry PI (probably the latter is better - it has multiple USB ports which can be configured as host or device). But then you'd end up with another point of failure. Two keyboards and two macs would be ultimate paranoia (and 2 PA mixers? amps, sets of speakers?). The pragmatic but robust solution would be to manually move the plug from one mac to the other in the highly unlikely scenario that the primary mac stops working. If you don't think that it's highly unlikely then you probably should get a new mac, because it should be!

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  • maltingsaudiomaltingsaudio Frets: 1763
    edited July 20
    Something like this should work, midi out of the controller into a split and out to the macs, but think your going to need three usb to midi leads https://kentonuk.com/product/thru-5/

    and https://www.amazon.co.uk/USB-MIDI-Interface-Cable-DigitalLife/dp/B077X7R74Y/ref=asc_df_B077X7R74Y/?tag=googshopuk-21&linkCode=df0&hvadid=218769691561&hvpos=&hvnetw=g&hvrand=8006770066846482736&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9045668&hvtargid=pla-782253932145&psc=1

    The macs don’t have to communicate with the controller so you don’t need a return so use leave the midi in ends dangling!
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  • prowlaprowla Frets: 3748
    edited July 21
    If it were round-pin DIN MIDI, a MIDI splitter should do it.

    Controller -> MIDI Splittter => MIDI-USB interface on laptop A + MIDI-USB interface on laptop B.

    For USB, it might be worth seeing if there are any KVM/video splitters which could do the job (companies like StarTech, Lindy, and so-on).

    I use a KVM switch with a single USB keyboard & mouse (and monitor) to connect to multiple computers, one active at a time, with a hotkey to switch between them.

    There may be similar USB splitters.

    However, having got it all connected, I don't know how you would guarantee that both laptops were perfectly in sync, though.

    If you are wanting a seamless pro-level computer fail-over system, it could get really pricey.

    And, of course, if you are starting on an N+1 high-availability config, then you also have to start looking at what other parts might fail...
    • Are both laptops plugged into the same power supply?
    • Are they both on the same desk and so could a spilled beer take them both out?
    • Is the MIDI splitter reliable.
    • What if the controller fails?
    • Is the cable from the controller to the MIDI splitter reliable?
    • etc.

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  • Danny1969Danny1969 Frets: 6729
    Thanks for the suggestions. I think the problem I have is my controller keyboard is USB and not MIDI DIN .... If It was proper MIDI I could split the midi into 2 and feed 2 MIDI to USB adapters to both machines 

    Power supply failure isn't a problem since both Macbooks could do the whole show on their batteries. Sync isn't an issue as there's no playback, it's all played live from the controller keyboard and Mainstage is only providing the strings, brass etc

    It's theatres so on proper stage, no punters near me or beer to spill. Any problems with mixer, amp, speakers isn't our responsibility as that's in house.  

    I could use a 3PDT switch to toggle the controller from one Macbook to the other but I liked the idea of both Macbooks being triggered and toggling the audio out in event of a failure 

    @urban_winter ; It's the software that can be a touch flakey, I'm confident in the Macs, both were repaired and refurbished by me and both are the rock solid A1398 which is the best Macbook Pro's made and far more reliable than the current models. Your right though, it's the 2 host and one device rather than the other way round that's the problem. 

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