How do you control the volume of FM Parts?

There are several ways to control the Volume of an FM-X Part. FM-X responds to velocity from the keys, messages from arpeggio phrases, and of course, to assigned controllers, including the physical controllers and controller messages automated in Motion Sequences. In a case where the volume setting is shown at a value other than what you are hearing simply means the output level of that Part is beIng controlled elsewhere.

For example the volume slider control you see as Part Volume is addressed by cc007 main Channel Volume. The Montage has other methods of addressing the audio output via its direct parameter assignments. For example, the overall volume of a Part may be assigned to be controlled by the Motion Control engine (an Assignable Knob linked to the Super Knob movement), for example. In which case the Part Volume FADER would not represent the current volume. Rather it would represent the stored initial setting of that PART... control during performance is not going to necessary involve moving cc007.

If you give a specific Performance we can help translate (maybe) what is going on... It is not just true of FM-X Parts but AWM2 Parts, as well. The slider volume at 0, might be used to start a Part at minimum (so the stored value is 0) then an assigned function may be responsible for bringing the output level up. You are not just limited to controlling output level with just the usual cc commands. In fact cc (Control Change) messages address everything on the channel. When playing multiple Parts simultaneously you want/need to have a method to address and control individual Parts separately. Using a cc 007 (the main channel volume) message would cause all items on the MIDI channel to respond to that value.

Thanks. I think I understand so here is the Pad/Choir Performance I was working with:

FM Strings& Bells

I wanted to adjust the volume of Parts 3 and 4 which are both FM Piano.

In this PERFORMANCE you have two PARTs (1&2) doing FM Strings and two PARTs (3&4) doing the FM Bells.
The Super Knob (or Foot Controller 2) will simultaneously turn the Volume of the Strings down as it is moved from its start position (clockwise) and turn the Volume of the Bells up. If you turn the Super Knob counterclockwise the Bells will reduce to 0. While the Strings play at their stored Volume.

The Super Knob is stored so that it is at the CENTER position (64). You can position the Super Knob to affect any balance you desire and STORE the PERFORMANCE.

Since Parts 3 and 4 have their PART VOLUME stored at 0, when the Super Knob is set to minimum, you will hear no Bells at all.

You can edit the values within the Performance or use the FADERS when set to "PART 1-8" (COMMON)
The value set for these FADERS will determine the OUTPUT LEVEL of the PART when the SUPER KNOB is at minimum setting.

You can use the FADERS 1-4 to influence the PART VOLUME of each PART 1-4.

How it is done:
Assign Knob 1 is set to turn up the Bells in PARTs 3&4
Assign Knob 2 is set to turn down the Strings in PARTs 1&2

On the upper COMMON Level of editing (COMMON/AUDIO) you will find that the following PARTS have their Assign Knobs linked to the Super Knob:
Part 3 Assign 1
Part 4 Assign 1
Part 1 Assign 2
Part 2 Assign 2

The way the values and Curves are set determines at what position of the Super Knob these values pass each other.

By linking Part 3's Assign Knob 1 and Part 4's Assign Knob 1 to the Super Knob turn this up brings in the Bell sound
By linking Part 1's Assign Knob 2 and Part 2's Assign Knob 2 to the Super Knob turning this up removes the String sound

This is accomplished within the PARTS you will see the MOD/CONTROL > CONTROL ASSIGN is changed in a POSITIVE value for the Bells and a NEGATIVE value for the STRINGS.

If you would like to Bells when you initially recall this sound you can STORE the PART Volume for PARTs 3 and 4 at a higher value.

If you need to adjust the volume relative to each other, you can affect the overall level within the PART.
Within each FM-X PART you have both a 3-band EQ (pre-Insertion Effect) and a 2-band configurable EQ (post-Insertion Effect). On the screen with the 2-band EQ you will find a straight cut/boost for OUTPUT LEVEL (-/+12dB) control.

Linked shots below:
The first screenshot shows how PART 3 behaves in response to ASSIGN KNOB 1 (Part 4 is programmed exactly the same)
The second screen shot shows how PART 1 behaves in response to ASSIGN KNOB 2 (Part 2 is programmed exactly the same).

The PART Assign Knobs are linked to the Super Knob.

Thanks BM. I will need to print out your response to keep as a reference and probably read it a few times.