In simplest terms A HARDWARE device NORMALLY passes "through" to the MIDI THRU port any, and ALL, channels and MIDI data that come in the MIDI IN port unmodified (usually).

So if N channels of data come in, doesn't matter WHICH channels, then N channels of data go right back out on the MIDI THRU port, and on the same channel assignments they came in on, with minimal delay (for most HW it is usually not more than around ~3 milliseconds - but that delay adds and becomes noticeable if you start chaining HW MIDI IN's to MIDI THRU's after just 2-4 synths (depending on SYNTH mfg and its vintage) .

And let us not confuse MIDI THUR with MIDI OUT. Usually you (via programming) and the unit (depending on functions on capabilities) decide what, if anything, that comes in MIDI IN goes to the MIDI OUT plug - it may or may not be what came in, it more or may not be on the same channels, it may not even be ANYTHING that came in at all..

SOME units have a dual purpose port and YOU decide if that port is assigned as a THRU or an OUT.


After all my hot air above - BIAB is NOT a HW device, and for good or bad the PG programmers decided (and probably because MOST channels are needed by BIAB for all the BIAB parts if you are sending them out to a MIDI synth like a Sound Canvas) that they would allow for, and assign, ONE channel as a THRU channel for whatever use the user wants, - as simple as that.


Good Luck
Larry

Last edited by Larry Kehl; 07/03/16 01:29 PM.
Win10Pro,i9,64GB,2TBSSD+20TBHDDs,1080TI,BIAB'24,Scarlett18i8,Montage7,Fusion 8HD,QS8,Integra7,XV5080,QSR,SC-8850,SPLAT,FL21&others,Komp.14,IK suite&others, just a guitar player-AXE FX III &FM9T, FishmanTP, MIDIGuitar2, GK2/3'sw/GI20