Building MIDI Interfaces 1 IN 1 THRU 3 OUT?

[gertsy]

I am guessing you are looking for multiple outs? Though you haven't said.
You can run multiple outs from the tx out of the midi interface opto isolator.  Most opto isolators have an in, thru and out pin. You can use the tx out(to pin 5) signal ground(to pin 4), and earth(to pin 2) to multiple midi out sockets. Amiga midi interfaces are much easier to build than the pc equivalent as Amiga can run at the midi baud rate where the pc requires buffering. As far as I can remember.

[gertsy]

Yes... an adapter that "lives up to that standard" aka 1 in 1 thru 3 outs.

Is there a guide for this, I don't even know what tx out is.

2 Choices:

1. You use one of the aminet schematics and duplicate the connections of the single midi Out to 2 other sockets. Giving you 3 midi outs.  Just wire 3 sockets exactly as if they were each individual out sockets. You can't fit them to the circuit board but you can mount them on short cables in a jiffy box that holds the circuit board.
2. Buy a standard Amiga midi interface with one out and rig up your own triple headed midi out cable. One plug into the interface Midi Out and three cables and plugs coming out of it for your instruments (Midi INs)

I actually built my own Amiga Midi Interface from a schematic and supplied circuit board and I just ran 2 out cables (around a metre long) directly from the circuit board for the single out.  

The standard says all devices should be opto isolated from each other and by doing this you are actually hooking end devices together un-isolated but in all reality if a device or interface blew up or surged the signal earth is most likely gonna carry something nasty whether the signal line is opto isolated or not.  There are many musical instruments that have direct serial connections or com port connections for PCs or Macs with no opto-isolation at all.

PS: You do know you can just use the Thru port of a connected midi instrument to daisy chain a midi cable to another instruments Midi In ?

Note.  Just a word of warning. If you make yourself a 3 way Y splitter cable you can only use it one way; From a Midi Out on your interface to the Midi In of your 3 instruments as end of chain devices. Don't try use it to the Midi IN of another Midi Interface or a DAW or USB Connected Sound Module. Label it clearly to say that.  And don't use the cable backwards from multiple Midi Outs in your instruments to a single Midi In on an interface you will just garble the midi in signal.

[gertsy]

Alright, I think I get your basic meaning. When I get my pieces in the mail, I'll ask questions and post photos as I go. I'm not a master electrician, but I know enough to do basic Atari 8-Bit mods and the like so I'm sure I can tackle this.

As for MIDI Thru. Maybe I've not tinkered with it enough yet, but lets say I have a midi instrument that my out from the Amiga is going to, and from there I have another instrument connected to it's thru. Since they are both on the same MIDI channel, I'm not sure how to prevent the second instrument from picking up on commands that were intended for the 1st. Though as I say, maybe I've not messed with the thru feature enough yet.

No you have it right.  If you have 3 midi instrument devices on a chain and you have them all set to receive on channel 1 they will all play the same signal coming down the chain.
You have to set them each to different channels.  Drum machines usually default to channel 10 for this reason.

To be clear:  Your Midi Interface is connected to your Amiga Serial port.
The Midi Out of your interface is connected to the Midi In of your first instrument
The Midi Thru of your first instrument is connected to the Midi In of the second instrument
The Mid Thru of the second instrument is connected to the Midi In of the third instrument.

Set the first instrument to Channel 1.  The second to Channel 2 and the third to Channel 3. (Unless one is a drum machine which defaults to 10).

If one of the instruments is a keyboard you want to use as a controller then it should be the first instrument in the chain.  You connect the Midi Out of that instrument to the Midi In of your Amiga Midi Interface.

FYI. Midi thru on any Midi instrument just parrots what comes in through the Midi In.  But it is opto-isolated, safer than hot wiring.