DIY midi switching

[Rylan]

So I'm building a midi switch for a custom application in my studio, I understand that you really only need the 2, 4, and 5 pins and the other 2 are not used?

Can I completely omit pins 1 and 3 in my switch then? A 6 gang switch is cheaper than a 10 gang, and easier to fit in a small box.

Also, if only 3 pins are used, why isn't midi done on 3 conductor cable? Manufacturing/impedance?



I was going to post this in low end theory but I get dumb responses there so sorry this is not really very geeky.

[a zombie]

You are right that midi only uses 3 of the 5 pins. Thus I use XLR jacks for midi conections in live applications as they are easily extendable and much more reliable.

I'm assuming you're switching both the in and out at one time, so need 6 poles..?

If yes you should be able to use a 6 gang switch. You could also use 3 DPDT relays and an SPST switch, if you only need 2 positions.

I was told the reason that midi uses the DIN5 connector was so that you could have in and out on one cable.

[Rylan]

Awesome, thank you kindly for the detailed answer. I had not thought about using the spare pins for a return signal, this may further simplify my design! Cheers!

Edit: oh and yes it is an in/out switch, easier to just have a hardware switch for i/o than soft switch due to the risk of software being slow or glitchy and creating midi feedback with my standalone midi router.

[Rylan]

One further question if I may ask...
I am somewhat inexperienced with relays.

What sort of relays could be used as midi switches?

All I know of relays, is related to household current 120~ AC types.

[a zombie]

The relays I'm talking about are basically just a 2 pole 2 position switch that is controlled by a DC voltage. So when there is the switch is in the one position, and when power is applied the switch flips to the other position.

It is basically a electro-magnet that pulls on a switch element.

The nice thing about a relay is that you can have an almost infinite number of poles that can be controlled by a simple SPST switch

The bad things about relays are a) they need power b) there is obviously more wiring involved and c) having more than 2 positions starts to get pretty complicated.