Sorry for responding with so much delay. I’ve been busy and haven’t been on here much…
Much of what I’ll say here, you will already know… but I always like to go into a bit more detail, for people who may be reading along. It might be helpful to them (and it helps me organize my thoughts).
The D8B was of course mainly designed as a digital mixer. Making it usable as a control surface was just some half-baked extra feature, by making it possible to use 8 of the faders (17-24) in HUI mode. Not particularly useful, IMO… but better than nothing for the time.
So, I’d think that most customers who bought a D8B new, didn’t even realize that most of the buttons and faders, etc. on the D8B, would not directly pass audio like on an analog mixer (even though that’s pretty clear, if you have the ability to switch between the Mic/Line and Tape-In layers, etc.).
Instead of passing audio, the majority of the buttons and faders on the D8B just send and receive MIDI commands, to communicate with the CPU unit in the rack, via the "Console-Data" DB25 connector (where the ProBox is connected), and through that, the signal goes back to the DSP/Brain boards inside the console, to change the settings where the signal is actually being processed (i.e. the DSP cards in the console).
I'm not sure if some of these signals go from buttons to DSP boards directly, without going to the rack unit... but let's just assume for a moment, that most everything that is MIDI, passes over that DB25/Console-Data connector.
The MIDI commands the D8B uses were intended as a proprietary communication protocol, just to make all the components function together as a unit (…well, maybe there were plans to expand it beyond that, and beyond that half-baked HUI implementation, but I want to keep things simple enough. At least that functionality expansion never happened during the D8Bs life cycle as an actively sold product, and only happened when the ProBox was available... well, and the D8Bridge software... but that's a similar, but different story).
As we all know, Mackie also made a control surface called the Mackie Control, as well as the older HUI.
Someone apparently had the idea at some point, that you could tap into the MIDI communication inside the D8B, by intercepting it at that DB25/Console-Data connector. You could read out all the proprietary MIDI messages each button or each fader was sending, etc. The next step was, to figure out what the (mostly different) proprietary MIDI messages were that the Mackie Control (and/or HUI… that’s yet another language/protocol) were sending, when a button was pushed or a fader was moved. And lastly, once you got all those MIDI messages logged and mapped, you could “translate” a D8B MIDI message into a Mackie Control (or HUI) MIDI message, and vice versa.
…and that’s what the ProBox does. It’s translating MIDI messages in real-time. And it even “speaks” the Mackie Control “language” as well as the HUI “language”, and can translate both. So, essentially, it turns a D8B into a Mackie Control unit with two Extenders (and an analog Monitor Controller, similar to the Mackie Big Knob...and some other configuration options that you don't have on the original Mackie Control, for metering, fader calibration, etc.).
The trouble is, though, that some buttons or knobs on the D8B don’t use MIDI at all, and are simply analog components (e.g. the “Mic” switches on channels 1 -12, or the pre-amp pots…and I think some of the stuff in the analog monitoring section). Other buttons/components may be digital and send MIDI, but have other limitations (that I’m not familiar with), and/or may only send messages to a DSP board inside the desk, and not out via the DB25/Console-Data connector on the back of the desk. If the signal isn’t plain MIDI, and/or isn’t sent over that Console-Data connector, then you can’t tap it, and you can’t translate it, with a device that sits outside of the console.
I don’t really know the technical reason, but that’s kind of what I suspect might be going on here, and why the “Write” buttons aren’t useable in the way you would like. Besides, the original Mackie Control unit doesn’t have a ‘Write” button on each channel. That may very well be, why you first have to push another button to activate “Write” mode (via the Aux 9-10 button), before you can choose the channels for which this will be active. But I’m really not sure about the exact reason. I have to admit that I’m not using those features that much on the D8B. I just enable that stuff in software… I have an odd hybrid workflow.
But still, the ProBox didn’t really re-invent how the Mackie Control or HUI communication protocols function. So, if that works a certain way with an original Mackie Control (e.g. b/c there are no write buttons on the channels), the D8B w/ ProBox will work the same way. None of that was changed in the design of the ProBox from what I understand. It’s just translating. So, that’s why some button’s functionality isn’t working quite as expected, IMO.
About the Banking of faders in groups of 8 - there’s a simple explanation for that, though: The Mackie Control and HUI control surfaces both have 8 faders. That’s why the default is, to bank over by 8 faders/channels at a time. However, some DAWs allow you to change that inside the DAW, where you would configure your Mackie Control or HUI behavior. But of course there were expansion modules called “Mackie Control Extenders” available, where you could add as many faders as you want (in banks of 8)… and then you’d also be compelled to jump banks by as many faders as you have in total.
In Logic, for example, I’m fairly sure that it’s possible to configure how many channels you want to bank over with a single button push - although it might do that automatically, depending on how many Mackie Control units and extenders are detected, I’m not sure. But I recall changing that at some point, but don’t remember if I had to hack a preferences file for it, or if it was in the user interface.
Another example for a parameter that configures Mackie Control functionality, that isn’t available in all DAWs (…and is one of only a few things that keeps me from switching to Studio One), is that Logic has a setting called “Track Lock” under “Logic Menu->Control Surfaces->Preferences” (then select the unit you want to change this for).
As mentioned, I have two D8Bs and two ProBoxes. My main D8B works like everyone else’s, and dynamically switches channel assignments, according to the buttons I push (e.g. Audio Tracks, MIDI Tracks, Virtual-Instruments, etc.). However my second D8B, when in ProBox mode with Logic, I configured what channels I wanted on which fader, and then turned “Track Lock” on. It’s static, and all faders always have the same assignments, and I want it that way.
What that does, is that no matter if I switch the first D8B between different types of channels, the second D8B will always display the same channels all the time. For me, that’s my Busses, Auxes, VCAs, Master channels, and also the Click-Track, etc. So, more for controlling summed stuff and groups, send levels for what goes out to external gear, etc. This makes it more similar to working with a large format console, where that stuff is just always where you’d expect it to be (i.e. in many cases, on the other side of the Master Section… just like it is for me, here).
Honestly, I think if the D8B had channel displays, that wouldn’t even be that important for me… but I hate it, if I have to search which channel does what, and even just touch the wrong one, where I had carefully set the levels for before. So I have all the Summing and General Stuff always on the same faders (using a template when starting a new project), and the other D8B has a monitor-screen over it, that aligns pretty well with the channels… so it’s sort of OK to figure out where what is… but still not perfect.
…sorry, I got a little side-tracked. My point is, that Studio One does NOT have the Track Lock parameter, and I can’t use the dual D8B/ProBox setup in that way with it. This is important enough for me, to stick with Logic for now.
Long story short, some DAWs may give you access to the configuration for some Mackie Control protocol parameters (e.g. Channel Count for Banking, Track Lock), while others don’t.
Again… sorry for the long post, but I type about as fast as I speak, and didn’t feel like working right now, so I slacked off for a bit and typed this
All of this is probably not that useful for you, in Studio One, but maybe it helps someone else to understand why stuff does what it does and how (…if anybody really has the patience to read through all of this, hahaha).