I use an FC-7 expression pedal to control the volume of certain Parts. Can I also make the expression pedal control the volume of this bass Part which is activated by the MIDI bass pedals board?

Controlling the volume of Part 8 would be no different than controlling the volume of other Parts.

Considering you are using Part 8 with Keyboard Control=OFF, it may be better to place the pedal bass Part on any Part from 9-16 to free up Part 8 for another keyboard control Part. Given you are using Part 8 on MODX - you're already not concerned about SSS - so this is not a consideration vs using Part 8.

Jason, the expression pedal only controls the volume of the MIDI bass pedals if I select this part on the MODX (on Part level). If I select a Live set or Performance, the FC-7 pedal does not control the volume of this MIDI Part, even though the RC Switch for Vol/Exp for this Part is set to On.

I use an FC-7 expression pedal to control the volume of certain Parts.

There are actually multiple ways to employ the FC-7 to control Part(s) and perhaps you are using the way that will not work for Part(s) with Keyboard Control = OFF. The reason for this is that keyboard control=OFF means "controllers off" for this Part - not just the piano keys - but other controllers too.

When trying to address keyboard control=OFF Part(s) - and, BTW, this works for keyboard control=ON Part(s) as well - you would use superknob. The expression pedal would be used to move superknob and then superknob would connect to a common assignable knob that would, in turn, connect to one or more Part-level Assignable knobs and the Part-level assignable knobs would control Part volume.

The superknob -> assignable knob(common) -> assignable knob(part) -> destination (Part volume) assignments work for any Part regardless of the keyboard control setting.

When playing my MODX, I often use MIDI bass pedals to play a bass-sound which I set on the MODX as a Performance Part for MIDI channel 8 (Kbd Ctrl off). I use an FC-7 expression pedal to control the volume of certain Parts. Can I also make the expression pedal control the volume of this bass Part which is activated by the MIDI bass pedals board?

Your standard Controllers work on the MIDI Channel on which you are transmitting. By setting the KBD CTRL = OFF for Part 8, you have removed the ability of using the FC7 sending CC11 Expression to PART 8, unless you select it directly.

KBD CTRL linked PARTS will be accessible any time you are on "COMMON ground" - this means any time the cursor is highlighting the PERFORMANCE NAME or one of the KBD CTRL Parts is selected... KBD CTRL is one for all, all for one... Selecting any one of them means they all are accessible from the keyboard and controllers. They are a group.

Fortunately, for you, you have access to controlling the Volume of PART 8 in several places. You will need to choose the one that works for you...

_ The front panel Slider #8 will control the PART VOLUME of the Bass sound in Part 8 -- and this is whether you have directly selected it or not. In other words, you can be on the HOME screen with the Performance Name highlighted (the condition in which all COMMON Parts - the KBD CTRL linked Parts - will be accessible)... yet you have a dedicated Slider for PART 8.
On the MODX you would need to set the four Sliders so that 5-8 are active. The button labeled [1-4/5-8] located just to the left of the Sliders will let give you access to Sliders 5, 6, 7, and 8, respectively. The FC7 sending CC11 will control the KBD CTRL linked Parts, while the Slider #8 will be your independent Volume for the sound the Bass Pedals are triggering.

_ (If you absolutely, positively, require a Foot Control) The Super Knob can address any PART 1-16 whether or not you have selected it - It works under any and all conditions. Any PART whether it is 1-8 or 9-16, any PART. Not sure how many FC7s you have but I was able to set this up in no time with my two FC7s.
Foot Ctrl 1 is set to CC11 and allows me to control the KBD CTRL linked Part's Volume as usual when on 'COMMON ground'.
Foot Ctrl 2 is set to Super Knob. I program the Super Knob to control PART VOLUME for PART 8
The thing here is that you are dedicating the Super Knob to control PART VOLUME of the Bass in Part 8... which may conflict with what else you have assigned to it. The thing about this is all things that the Super Knob is controlling will be influenced when you move the second FC7... you can dedicate it to control the Volume of Part 8.

_ If you need the Super Knob for other duties, and you have an available Common Assign Knob, you can assign that Knob to be the Part Volume for the Bass sound in PART 8.
From the HOME screen tap "Motion Control" > "Super Knob" here you can unlink on of the COMMON ASSSIGN KNOB from Super Knob Control... Make it a dedicated Volume Control for your Bass Sound. (No Foot Control but your feet are busy dancing on the Bass pedals...)

You'll need to decide which is best for you.

It is also possible to reprogram whatever you have the Super Knob doing - to accommodate what you want to accomplish with the Bass Pedal's controlled sound.

Hope that helps.

_ The front panel Slider #8 will control the PART VOLUME of the Bass sound in Part 8 -- and this is whether you have directly selected it or not. In other words, you can be on the HOME screen with the Performance Name highlighted (the condition in which all COMMON Parts - the KBD CTRL linked Parts - will be accessible)... yet you have a dedicated Slider for PART 8.

Thinking ahead - if you do decide to place the bass on Part 9 (or above) to give yourself more keyboard-controlled Parts - then the slider approach won't work "seamlessly" as it does when using Part 8.

The reason for this is that when you switch the Sliders to address Parts 9-12, automatically Part 9 is selected which will (however briefly) take your keys away from Parts 1-8. This may not be desirable depending on how "busy" you are with playing Part(s) while controlling volume.

Commentary: automatic Part selection is one of those things I wish wouldn't happen after setting the sliders to use Parts in the range of 9-12 or 13-16 or 9-16 (for Montage) to allow for using sliders to adjust levels without selecting Parts -- but that's how it works.

Thank you both.

Given the importance of volume dynamics across various instruments/parts while playing (similar to how a conductor doesn't want the bass and cello sections to ignore his guidance), I find it dissapointing and also quite strange that you apparently can't use an expression pedal to control volume over multiple hardware sources (bass pedals, 2nd keyboard, etc.) without 1) using the part knobs as volume controllers only (duplicating sliders) and 2) reducing the Superknob to a 'dumb' connector of volume control knobs and the expression pedal. In my view, this is such a big thing that I would vote for "being able to control volume of MIDI parts with Kbd Ctrl off" as an enhancement request.

Here's an alternative suggestion:

Referring to Part 8 throughout:
1) Turn on Part Zone Master
2) Make sure Int SW is ON. Int SW (internal switch) will cut off the tone generator from this Part no matter if the local keys are used or an external controller. The docs do not read this way - so it's worth clarifying.
3) Set the Zone's note range to C-2 to C-2. I'm assuming your keyboard is not [OCTAVE -] adjusted such that C-2 is an available piano key to you. What this does is prevents the local keys from triggering this Part while still allowing the external MIDI bass pedals to trigger this Part. This Part Zone note range applies to the local keys and not incoming MIDI. I've tested this with a 5-Pin DIN connected MIDI keyboard. If your local keys (due to octave shifting) can reach C-2, then maybe pick the range of G8 to G8 instead. Goal here is to set a single note in either extreme that you'd never press with the local keys. A pseudo-local-piano-keyboard-keys-OFF setting.
4) Set Keyboard Control for Part 8 to ON. Leave it ON so you can use the expression pedal in the way you normally do to control Part volumes.

I think this gives you the control and functionality you ultimately want. The problem isn't necessarily the available options - but so many things are "in the wrong place" to make intuitive sense. It's true that there are "you can't get there from here" situations - but most of the time it's just the issue of grappling with where to find the feature or how to maneuver through the dependencies/rules to (correctly) program the desired outcome.

I'm not really defending anything here - I think the reverse-Polish approach to calculators is unnecessarily complex. There's a group of calculator users that enjoy that kind of thing and they have some points when it comes to efficiency. However, it's quite inefficient for most to "remember" how to rethink what otherwise has a different order of operations and so for the majority - a TI graphing calculator with standard notation wins over the HP reverse Polish. This calculator reference is analogous to how I feel about Yamaha's user interface at times.

All of that said - once you learn (or learn, then forget, then have to re-learn) - at least you end up with something that works. I advocate keeping a notebook with the various rules and conventions. Not necessarily because it's absolutely required - but because the system isn't intuitive enough that various features would be self-evident. You may want to relate to a "strange" setting in your own terms in the future rather than docs, this message board, or anywhere else you may go to re-learn a past stumbling block.

Brilliant!! This is the PERFECT solution Jason, thank you so much: super easy and 100% effective! The value of your solution goes way beyond bass pedal boards: this enables every keyboardist who wants to play MODX or Montage performances using multiple keyboards, to fully control volume using an expression pedal while keeping their hands on the keys!

This is very much by design... The Yamaha Master Keyboard function, has been working like this for many, many years - you have the option of setting the ZONE to trigger internally, externally via MIDI, either or both - and you are also given control over what Controllers will be sent (Zone Transmit) per ZONE slot. The Master Keyboard function is all about what is TRANSMITTED by the MODX/MONTAGE as a whole. When ZONE MASTER is activate you are given two additional screens per Part: Zone Settings and Zone Transmit

Rather than just a Transmit Switch ON/OFF for KEYBD, they give you a very flexible Low/High NOTE LIMIT function on the setup screen. This allowed the performer the ability to create a region where the ZONE was and was not transmitting. Quite different from receiving, obviously.

In researching this, because it is something that has been in Yamaha synths for many, many years... I ran into a couple of old posts that had me smiling.... Here for the MOX (from 2011)
Link -- http://www.motifator.com/index.php/forum/viewthread/456033/

and I found a familiar face -- this for the Motif XF also 2011
an old motifator.com post 11 years ago (from YS.com poster, Michael Trigoboff) where on an Motif XF he was using some of its 8 Zones to create additional controllers. On the Motif XF you were limited to one Control Slider and one Knob per Zone (the old days).

If we could go back to CompuServe I bet we could find a thread on this...

Back in the Motif XF, (which has essentially the same Master Mode as MODX/MONTAGE with the exception that the setup is included in each Performance rather than being a separate Mode) - you could get creative... Setting up what we called, back then, a "no-fly" zone, this is very much by design.

Let necessity be the mother of invention. Just because it is not specifically detailed in the manual - doesn't mean the designers where unaware of the implications. They simply present that the Low Note Limit can be set higher than the Low Note Limit... it is for the user to be creative.

Nobody wants a manual that is 1000 Pages (don't laugh) - remember when they used to print out DAW software manuals - they came as "loose leaf" books so you could add chapters when they added new features... they weighed like 5 pounds, and were well over 1000 pages...
I think an alternate method to all that print is what we have here... online communication with a community looking to share what the product CAN do (not just lamenting over what it does not do).

Glad that I was right thinking that there had to be a solution for controlling multiple keyboards with one expression pedal, other than abusing part knobs and the Super Knob. I'm really glad that Jason recalled this Zone switch solution, which you apparently had already provided over 10 year ago! Many thanks for your help, both!