Unless you are sending that single voice track through a completely different physical output on your audio card (== track routing), you can’t really process the master channel while excluding a single track. The master is everything
And if you are using send tracks, it’s a tricky - especially if the vocal is using the same send tracks as the other tracks. Then you might:
Duplicate affected send tracks and make your vocal use an exclusive set
Moving whatever DSP effects you are using into the vocal itself (copy DSP chain, paste into instrument.
Send tracks or not, the next step would be to collect all the tracks that should be processed by the filter in a big group.
I understand the use and purpose of the “Master Track”, and that it is like a real master output. I will try what you suggest and I’ll find eventually a workaround, I always do, but there should be a “sub-master” where you select tracks to apply specific effects or way to do something like I suggest in future versions of Renoise.
Don’t get me wrong, I think Renoise is one of the best and most powerful and, may be by some people, underrated audio software, but sometimes it make what one think should be “easy” tasks a little harder than other environments.
But I’m so much in love with Renoise, that I forgive everything…