UNO Drum and UNO Synth midi connection [SOLVED]

[albertpauw]

Hi Peter/Ryan,

I was just thinking. If you want to connect UNO drum midi out to UNO synth midi in (for the midi clock), is it possible to use a (modified) cable to directly connect the 2.5 mm midi out jack from the drum to the 2.5 mm midi in jack of the synth just to avoid all the cable clutter with real midi cables and the two midi dongles?

If there is some opto coupler needed, maybe it is an idea for IK Multimedia to sell the cable, or publish the schematics and wiring?

Just a wild thought really.

Regards,
Albert

[Peter_IK]

The wiring is the TRS wiring that the MIDI Association made a standard somewhat recently so that actually may be possible to directly connect. You can find more information about the spec here: https://www.midi.org/articles-old/trs-s ... d-released

[albertpauw]

HI Peter,

thanks. So, a stereo 2.5mm jack-jack cable between a midi out on a UNO Drum and midi in on a UNO Synth would do the trick, no crosscabling needed. Can you confirm?

Now that is simple and convenient

Regards,
Albert

[Peter_IK]

HI Peter,

thanks. So, a stereo 2.5mm jack-jack cable between a midi out on a UNO Drum and midi in on a UNO Synth would do the trick, no crosscabling needed. Can you confirm?

Now that is simple and convenient

Regards,
Albert

It would need to meet the wiring specs/etc at the link I provided. I do not have a cable like you mention to test directly.

[albertpauw]

Hi Peter,

I assume using a shielded cable would be necessary. The thing I was thinking about is, does it need pull up resisters are opto couplers, etc? If the Midi dongle is just a wire connection without any electronics inside, then a decent shielded stereo wire with 2.5 mm jacks would be sufficient.

I hope you can confirm this, it would make wiring up the UNO's very simple.

Thanks for your replies so far,
Regards,
Albert

[Peter_IK]

Support confirmed a 2.5mm standard audio cable will not work, as expected. You'd need one specifically wired to the MIDI spec or to use the adapters + 5-pin MIDI.

[albertpauw]

Thanks,

Kind regards,
Albert

[Peter_IK]

Thanks,

Kind regards,
Albert

No problem. I'm also looking at the full downloadable spec for the 2.5mm cabling. I don't see these available without 5-pin ends/breakout so I am wondering if a direct 2.5mm --> 2.5mm could be made somehow efficiently and fairly easily.

[albertpauw]

Hi Peter,

it depends if there is any electronics inside the Midi dongle that comes with the UNO's.
If there are no pull-up resistors or opto couplers, but just wired up to the DIN plug then it is possible, you may have to twist the tip and sleeve contacts between them.

Just my two cents.

[Peter_IK]

Ours follow the standard at that link (we're a MIDI Association partner) so it should be possible to wire both ends of the 2.5mm connection in a way that works if I'm not mistaken though I haven't been able to dig into the PDF quite yet.

[albertpauw]

Just looked into the documents, a midi cable is a straight through cable, pin 2 -> pin2, pin 4 -> pin 4, pin 5 -> pin 5, so the 2.5 mm jack sleeve, ring, and tip should be connected straight through as well, a good quality stereo cable with 2.5 mm jacks would do the trick.

Unfortunately, I don't have a UNO drum to check this.

Regards,
Albert

[Peter_IK]

Just looked into the documents, a midi cable is a straight through cable, pin 2 -> pin2, pin 4 -> pin 4, pin 5 -> pin 5, so the 2.5 mm jack sleeve, ring, and tip should be connected straight through as well, a good quality stereo cable with 2.5 mm jacks would do the trick.

Unfortunately, I don't have a UNO drum to check this.

Regards,
Albert

Remember the shielding too, and our Support told me that they tried a straight audio cable and it does not work for them.

[albertpauw]

Thanks Peter,

since the MIDI serial speed is 31250 bits per second, a good shielded cable must be used indeed, so a standard audiocable (unshielded) is most likely a no go.

[albertpauw]

Hi Peter,

you probably have seen this as well:
https://www.youtube.com/watch?v=wz7dxEN2F28

But Erik Norlander mentions this to be working!

[albertpauw]

I finally had the opportunity to test this out.

UNO Drum -> midi out -> direct cable -> midi in -> UNO Synth

UNO Drum set to midi external in.

This worked fine. I had some trouble to find a 2.5 mm jack <-> 2.5 mm jack stereo cable, but finally found one.

It works fine, the UNO Synth follows the tempo of the UNO Drum, as it should.

Only thing I could get to work (in a quick test) is when I press start on the UNO Drum, it would not start the sequencer on the UNO Synth. So I guess the work flow is, start sequencer on UNO Synth (nothing happens as it is waiting for the midi clock), then start the sequencer on the UNO Drum. Which sounds logical.