Remove last 17 characters of a filename?

I have a set of files and the last 17 characters are always rubbish. Is there a way to remove them, no matter what it says?

I have looked in the "Actions" but it's not immediately obvious what I can do.

thanks for any advice

Alan

I think I need a regular expression. The bit I want to remove always starts with "b0" and always ends with "default".

Can anyone help provide me with this?

[edit]

so far I have " b0*" replace with "mp3" as the expression wipes out the extension.
Can it be better?

Alan

Help says:
$cutRight(x,n) removes the last n characters of string x and returns the result.

So for you: $cutRight(%_FILENAME%,17)

That doesn't seem to be doing anything. In the Field box, I have "_Filename" as the entry
In the Regular Expression box, I have $cutRight(%_FILENAME%,17)
In the replace with, I have ".mp4a" (or something else).

It does nothing at all.

Alan

You have to use an action of the type "Format value" for _FILENAME.

Alternatively, you can use Convert>Tag-Filename with the mask
$cutright(%_filename%,17)
This has even a preview.

Convert worked perfectly. Many thanks.

Alan