Possibly a ridiculous question about MIDI...

Mr36 · Post by **Mr36** » Tue Aug 17, 2010 6:42 pm

I wasn't really sure where to post this thread... Hope here is alright.

Maybe a really stupid question that deserves either an equally stupid answer or just a blunt one but...

What happens when you connect an instrument's MIDI out to its own MIDI in? Will it harm the instrument? Will it trigger itself via MIDI as well as internally? Will it double trigger and cause the sounds to phase? Or maybe it will just not do anything...

The main issue is the safety. I'd just try it if I was sure it wouldn't cause damage. Not sure how it would... But then, I am asking these questions, so what do I know?

Thanks.

axxim · Post by **axxim** » Tue Aug 17, 2010 7:18 pm

Hi,

if you connect the MIDI out to the MIDI in, what you play on the KB will go once direct to the sound engine (provided the instrument has one) and once to MIDI out (coming then to the in again). Doing this your sound engine will double play each note you press. This will sound a little different (like unisono or similar) and of course halve your polyphony. There will be no harm because what is transmitted is a serial binary data specifying what notes to set on/off and other control data such as pitchbend volume etc. If an excessive overload of data is send to the instrument to maost what can happen is the instrument ignoring part of them

Mr36 · Post by **Mr36** » Tue Aug 17, 2010 7:57 pm

Why, thank you very much. I may give it a try and I think I have a cunning plan to avoid the double-triggering...

axxim · Post by **axxim** » Thu Aug 19, 2010 11:41 am

Well, in most synths/workstations you can assign the keyboard to go to one or more MIDI channels only, without triggering the sound (for use as master KB). By the other side you can assign one or more MIDI channels to the sound engine. This way you would have no doublettes but what would be the sense of that? Its like sending the TV video signal to a video recorder and setting the TV channel to the external video source where the recorder is connected to to see the same again.

What some people does with older (analog) synths is that the (audio) line out is splitted with a Y-cable to connect one of them to the line input again (if the have one). This will create a feedback until overdrive/diestortion/self oscillation or whatever else, but this could damage the input amplifiers if done without knowledge and care!

jg:: · Post by **jg::** » Thu Aug 19, 2010 12:19 pm

A little correction - notes to MIDI In will NOT be re-transmitted via MIDI Out. They will, however, be re-transmitted from MIDI Thru.

In some Korg products, if there is a Test mode for use by service technicians, then sometimes they are directed to connect MIDI In and Out in order to test the MIDI functions.

jg::

synthjoe · Post by **synthjoe** » Thu Aug 19, 2010 1:31 pm

jg:: wrote:A little correction - notes to MIDI In will NOT be re-transmitted via MIDI Out. They will, however, be re-transmitted from MIDI Thru.

Precisely. Thru is the port to replicate MIDI in - but then again, if you connect 'thru' to 'in', there'll be no signal to loop back.

Midi OUT is for what YOU are playing on the keyboard - with a minor addition: some more sophisticated instruments will allow to produce several output events from a single operation (e.g. Korg T series allows to trigger up to 16 timbres/modules on two MIDI out ports at a single strike of a key), as well as there are some other devices allowing you to merge MIDI input with keyboard activity and transmit thorugh MID out. These latter ones are the only type where MIDI 'feedback' can occur.

But in short and simple: feel free to loop back, the worst case scenario is that you'll experience a minor sonic havoc, but you can get out of that by shutting down the synth or fiddling with MIDI settings to eliminate retransmission of MIDI in events on the out port, if that is possible on the instrument, at all.

Double strike is a normal occurrence: the key will trigger one note internally and another via the MIDI port. This is why 'local on/off' is implemented in most keyboards - it will switch off internal triggering of the sounds (i.e. the keyboard will go mute), but transmits MIDI data and hence looping back to the MIDI in port will fire only one note.

Hope this clarifies and was understandable at least to some extent - feel free to drop it if it wasn't.

axxim · Post by **axxim** » Thu Aug 19, 2010 1:59 pm

jg:: wrote:A little correction - notes to MIDI In will NOT be re-transmitted via MIDI Out. They will, however, be re-transmitted from MIDI Thru.
jg::

Who wrote that here?

synthjoe · Post by **synthjoe** » Thu Aug 19, 2010 2:51 pm

axxim wrote:
jg:: wrote:A little correction - notes to MIDI In will NOT be re-transmitted via MIDI Out. They will, however, be re-transmitted from MIDI Thru.
jg::
Who wrote that here?

jg is right - in general. However, some keyboards will allow MIDI merge, hence outputting MIDI in and actual keyboard activity together on their MIDI out - I believe Alesis QS series can do that. And most computer based devices do this merging. But in general keyboards (and surely so older ones) do not output their MIDI in via the out, but rather via thru.

axxim · Post by **axxim** » Thu Aug 19, 2010 7:01 pm

synthjoe wrote:
axxim wrote:
jg:: wrote:A little correction - notes to MIDI In will NOT be re-transmitted via MIDI Out. They will, however, be re-transmitted from MIDI Thru.
jg::
Who wrote that here?
jg is right - in general. However, some keyboards will allow MIDI merge, hence outputting MIDI in and actual keyboard activity together on their MIDI out - I believe Alesis QS series can do that. And most computer based devices do this merging. But in general keyboards (and surely so older ones) do not output their MIDI in via the out, but rather via thru.

I was referring to, who wrote something like "what comes to MIDI-In goes to MIDI-Out" in the previous posts which jg:: tried to correct?

In fact as you stated modern keyboards with only two MIDI ports (in and out) offer the option to output what comes in to emulate the physical missing MIDI-thru port (due cost reduction) which then would end in a endles loop. In this case and depending of the number of voices and their priority allocation, you could get a big unison mono sound or a fast musical machine gun

synthjoe · Post by **synthjoe** » Thu Aug 19, 2010 7:13 pm

Alright, finally I got it...

Indeed, precisely as you wrote - with the addition that the endless loop only happens if you can select a sort of 'merge' option. In the majority of cases when switching to 'thru' mode the actual keyboard activity is not routed to the (now 'thru') port. (Unless, of course, a computer is involved, but then it starts to get tricky, anyways...

)