MIDI Switch for redundant system

[Gareth Fry]

Hi all,

Slightly OT, but I have built a dual redundant QLab rig. I am looking
for a good solution to switch between the MIDI outputs of the two
machines. I've tried the MIDI Solutions PIS but don't find it
satisfactory. Can anyone else recommend anything?

Cheers,

Gareth Fry
Sound Designer
www.garethfry.com
gare...@hotmail.com

[Jeremy Lee]

Masque makes a custom box that does 16 channels of analog switching, MIDI switching, and includes a Go box solution. If you're going Analog, it's a perfect all in one solution. No idea if they would sell these on the market though.

You could probably just make your own with a couple of MIDI Din plugs and a DPDT switch if you wanted to.

Jeremy Lee
- A thumb is a terrible speller. Please forgive my trespasses.

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[ra byn (robin)]

On Wed, July 4, 2012 2:50 pm, Gareth Fry wrote:
> Hi all,
>
> Slightly OT, but I have built a dual redundant QLab rig. I am looking
> for a good solution to switch between the MIDI outputs of the two
> machines. I've tried the MIDI Solutions PIS but don't find it
> satisfactory. Can anyone else recommend anything?

Gareth,

Below is a response from John Fast @ Midi Solutions regarding this sort of
thing I dealt with a while back.

I ended up using a MS PIS & had no issues. Maybe you could explain why
your experience was "unsatisfactory".

ra byn

--------------------------------------------------------------------------

I'm not sure if merging two signals would cause problems or not, it depends
on the receiving device and what it would do in response. A box with a
switch should be fine provided it is not switched while MIDI data is passing
through it, if there is the possibility of this happening then it would be
better to go with a Programmable Input Selector. Ideally it would be best to
switch pins 2, 4, and 5, but if the two sources are in close proximity and
you are not worried about ground loops then you should be able to connect
pin 2 from all devices together and not worry about switching it, so yes,
switching pins 4 and 5 only should be fine.

The voltage between pins 2 and 4 of the Power Adapter are very close to
regulated 5V, pin 4 is actually connected through a 47 ohm resistor to
regulated 5V inside the Power Adapter.

John

[Gareth Fry]

Hi and thanks for replies.

I am all ADAT here and would prefer off-the-shelf solutions rather
than custom solutions for ease of swapping out faulty units.
There are a few hire companies in the UK who also make switching units
but they tend not to sell them on the open market because, I suspect,
that would make them liable to support them and they're plenty busy
enough as it is!

For those interested, the PIS has a MIDI A/B in, a footswitch in and a
MIDI out. You can switch the input with the footswitch - but I'm not
keen on toggle type systems as it's easy for them to fall out of sync
with the audio toggle and it gets a bit vague in a show emergency
which is active. I prefer the type of switch system where you press
one button for Mac A and another button for Mac B, and the audio, MIDI
and KVM switch to the appropriate computer. The Audio switch is
handled by a Friendchip DMX12 unit, FYI, which is very good. So to get
it to work the way I want it, I have to control the PIS using MIDI. On
Mac A I have a triggerable MIDI command that switches the DMX12 to
ADAT streams from Mac A and sends MIDI to the PIS asking it to switch
to Input A. Ditto on Mac B. However it seems that if the PIS is set to
Input A, it doesn't respond to a command in Input B asking it to
change to Input B, and vice versa. If it is set to Input B it ignores
the command on Input A to swap to Input A. I can't put the commands on
the opposite computer because the likely cause of swapping computers
is that one of them has crashed so I can't rely on the crashed
computer to send the necessary command!

So I'm interested if there are any other solutions out there?

Cheers,
G

Gareth Fry
Sound Designer
www.garethfry.com
gare...@hotmail.com

[Dominic Bilkey]

Hi Gareth,
I have just finished my prototype of my midi/ADAT/KVM switcher here at The Young Vic which does not rely on a machine to send the midi command but is handled by a programmed PIC chip which spits out the relevant preprogrammed midi on button pushes. This also switches a DPDT relay which switches the midi stream.

Current testing has proven that the system does not ever get out of sync as the midi pulse time for triggering the relays is programmable and therefore I have managed to tune this to reliably trigger.

Dom

[Gareth Fry]

Thanks Ken,

Yes, there seem to be a proliferation of products to do audio
switching. If you have a mid-sized Yamaha console with a spare card
slot you can also achieve this internally by recalling a scene memory
that changes the input patch. No hardware required.

There does seem to be a lack of off-the-shelf products for MIDI
switching though. One can just use a switch - though this will cut off
MIDI commands mid stream which is not ideal.

Thanks for all the responses.

Gareth

[Richard B. Ingraham]

> -----Original Message-----
> From: ql...@googlegroups.com [mailto:ql...@googlegroups.com] On Behalf
> Of Gareth Fry
> Sent: July 06, 2012 10:15 AM
> To: QLab
> Subject: [QLab] Re: MIDI Switch for redundant system
>
>
> There does seem to be a lack of off-the-shelf products for MIDI switching
> though. One can just use a switch - though this will cut off MIDI commands
> mid stream which is not ideal.
>
> Thanks for all the responses.
>
> Gareth

http://www.midisolutions.com/prodpis.htm

MIDI Solutions makes a MIDI Switch to allow for two computers to feed the
inputs and then it can be programmed to switch between them. Yes it
probably still would have the potential to make the jump in the middle of a
MIDI message and there by create some garbage. But I have used these in the
few redundant rigs I've designed and they work well.


Richard B. Ingraham
RBI Computers and Audio
www.rbicompaudio.20m.com

[Charles Coes]

MOTU MTP AV, recallable scenes that can trigger from MIDI. Not cheap, but readily available...

[Ben Emerson]

I've been wondering about this unit.  We're currently working with an old bu excellent MIDI patchbay, the MSB Rev 2, I can't off the top of my head (I'm sitting in a cabin on the Maine coast, so not near my gear) which I used as a MIDI patchbay in my studio when it involved numerous synths, a sample, a PC with a sequencing program and a MIDI Sysex editor.

I've been looking at the MOTU pieces as a possible replacement for this, since programming it is a bit kludgy.

Ben Emerson

On Sat, Jul 7, 2012 at 12:49 PM, Charles Coes <ccoes...@gmail.com> wrote:

MOTU MTP AV, recallable scenes that can trigger from MIDI.  Not cheap, but readily available...

--
Benjamin Emerson
Sound Supervisor
Huntington Theatre Co
Sound Design Instructor
Boston University Theatre