KC, I do things a little differently MIDI-wise ("master" controllers with a MIDI pedalboard and outboard gear, with everything on my floor pedalboard as "slaves"). Just a disclaimer before I try to help with your questions here, as that's not how I have mine set up. And you have a lot of loaded questions here.
Someone correct me if I'm wrong here, but the expression won't be re-transmitted from B to C. I'm not sure if you can 'mirror' all of the exact same settings for H9B and H9C, and have both respond to identical transmission from H9A. I've seen where users have 'split' the physical EXP PED cable to 2 units with success. Not so sure about 3 devices. For two H9s, it'd be something like this:
H9 A & H9 B = Set the XMT CHannel and RCV CHannel to same number [1-16 pick one]
H9 A Output Mode = Transmit [XMT]. H9 B Output Mode = THRU.
H9A XMT CC = PED > CC 15 (arbitrary). H9 B RCV CTL = PED > CC 15 (match to XMT)
Sorry to the 'mashup' of H9 Control settings, H9 inter-pedal, and PitchFactor thrown in together. I can point you to whatever you can't find in H9, but most everything you need for this is under PEDAL -> MIDI Settings in H9 Control. In General Settings, you'll need to have Expression Pedal enabled.
Um, yeah (my experience). MIDI DIN and USB share the same physical MIDI Port. I don't have MIDI over Bluetooth set up, so that may be an option. There's a new H9 Control feature under Settings: Connect MIDI Device to Eventide Device. The laptop that I'm using for H9 Control has no DIN port, and my audio/MIDI interface for it crapped out. Something to try out later.
Everything that you set up in H9 control gets transferred over to the H9 system settings, so you don't have to navigate the H9 menus for initial setup. But my current method involves unplugging the USB connections after setup adjustment – or preset programming – before actually using the pedalboard in a real-world application. In other words, insert USB for H9 Control adjustments, then disconnect to actually use what I just added.
Yes to the 1st question (caveats above). 2nd question(s): It really doesn't matter which CC message to use (in this situation). I think PitchBend is in there for PitchFactor algos used by (mainly) keyboardists with Pitch Wheels [although I have some issues with how the pitch functions land at a centered position].
The important thing is to match a transmitted CC number to a received CC number in the next device. There are 100 options here to make sure that one message doesn't control anything else, except for the functions you intend on the receiving device. The MIN & MAX values of parameter ranges can be a separate discussion. Easy enough in a Stompbox. Easier in H9 Control. I never set that up in the H9 pedal itself.
Again, CC 15 for the pedal is an arbitrary setting. The MIDI Spec suggests CC #4. Eventide set up some default numbers for aux switches and KB0-KB9 [Parameter 1-10], for both transmission & reception. They stay out of the way of each other. It may be a different group of default CC numbers for each Stompbox. Here, it won't matter. Specific CC numbers start to matter in synthesizers, or pedals on the same MIDI Channel that are locked to certain CC numbers.
Not that I know of. Effectively, that's what I'm doing with a "master" MIDI footpedal / switchboard, with all of my audio devices slaving to it. But I don't get visual feedback in H9 Control (for the reasons above). Once everything is set up correctly, I do get visual feedback from the displays on most of the devices themselves. For example, if I change MIDI Clock tempo, everything updates to the newest tempo. Or if I use MIDI to change multiple parameters on multiple devices, they all reflect those changes in the LED displays.
I don't know that I explained everything clearly here, so feel free to follow up. Any initial attempts at MIDI synchronizations are baffling & fraught with frustration. But the final rewards are well worth the effort.
