Muting a specific instrument

[just_some_dude]

I'm currently working around with a file, and I need to mute a few instruments in order to simplify the music. Attempting to adjust the volume has led to error messages, and I haven't figured out a solution to this. Thanks in advance for any answers.

[Saga Musix]

Attempting to adjust the volume has led to error messages

What kind of error messages? It would be new to me that OpenMPT has any error messages related to muting instruments. So I'd be curious to see this error message you encountered.

There are several ways to achieve what you want depending on the file format and type of instrument.
- If it's just temporary, you can mute instruments from the tree view. The mute status is not saved in files.
- You can set an instrument's or sample's global volume to 0. Note that this only applies to sampled instruments. If you are using instrument plugins (VSTi), you can instead choose "Bypass" in the plugin settings.
- If your instruments are organized into separate channels, you can mute those channels instead of muting instruments. Channel mute status is saved in the S3M, IT and MPTM formats; in MOD and XM it will not be retained when the file is closed.
- Alternatively you can set the channel volume to 0 in S3M, IT and MPTM formats.

[just_some_dude]

When I try to use Find/Replace to adjust instrument volume, I get the error message 

Code Select Expand

Cannot find "??? (instrument number) ??? ???"

[Saga Musix]

Well okay, that's not really an error related to volume adjustment... Note that if you want to use Find&Replace that you have to use instrument numbers, not sample numbers (as they appear in the pattern). If you were trying to find a sample number and there are more samples than instruments, the sample ID might exceed the highest instrument number.
Anyway, I don't think Find&Replace is necessarily the best tool for this task as it won't be able to remove stuff "between" notes (e.g. volume fades and the like). Do any of the above suggestions work better for you?

[just_some_dude]

May I ask how to adjust global volume? For my current needs, the tree view method is good, but I should still learn a different approach.

[Saga Musix]

You can do so on the instrument tab by setting the "Global Volume" field to 0. This is only available in the IT and MPTM format, though, XM doesn't have global volume for instruments.

There are many more creative ways to mute an instrument, too, depending on how destructive you allow the process to be. For example you could modify its volume envelope (in the lower half of the Instrument tab) to never rise above 0, or you could right-click on the note map (on the right side of the Instrument tab) and choose "Remove all samples". Both of those approaches would also work in XM, but due to their more destructive nature it might be more difficult to unmute the instrument.