Notch filter for isolating instruments?

I’m trying to work out how I can isolate instrument parts in a mastered track using Ardour. I’m looking for something (I think it’s a notch filter) that allows me to sweep up and down the frequency range boosting a narrow set of frequencies while the rest are suppressed. I’ve seen mastering engineers doing this while isolating individual instruments or particular frequencies to cut or boost, and would like to be able to do the same for isolating bass guitar parts when I’m transcribing them for a covers band.

Is this something I can do interactively in Ardour? I’ve tried doing this in the much simpler Audacity - it has a notch filter, but lacks an interface for sweeping through the frequencies to find the range that I want to isolate.

If you have a notch filter you can certainly do this yes, but it won’t really isolate any instruments, at best you will limit a frequency range to part of where that instrument resides and where other instruments reside less, but this is not what I would consider isolation.


The term you want to look for is “parametric equalizer.” Look for a plugin with that name, it allows you to pick the center frequency, the Q (which is how wide in frequency the equalizer creates a change), and the gain, which would be positive to boost, or negative to cut.
There are several parametric EQ plugins to choose from, just look around your favorite download site or the package repository for your linux distribution. Try out a few, and just pick the one with the user interface that makes the most sense to you.

– Chris Caudle

Hi Seablade,

I guess I should have been a little bit clearer that I didn’t mean completely isolating an individual instrument. The kind of software I’ve seen mastering engineers use allows them to boost a variable width of frequencies, with the remaining frequencies almost entirely suppressed. The engineers were able to drag that “cone” of frequencies around with a mouse until they found the right range. I guess I could contact the last mastering studio I saw this used at to see which software they used, but unlike Ardour, I suspect it wont run on Linux.



@Big Chris: If its a graphical parametric that you are looking for:

There’s a 4-band parametric EQ by Fons Adriaensen. I can’t remember what plugin package I got it in.

A multi-band compressor (eg from Linuxdsp) allows for an even more precise control of different fequency bands. For example, you could try to tame a boomy guitar by knocking off some peaks at the problem frequency range but leave everything else untouched.

I think you need both in the toolbox ie the standard multi-band parametric eq and a multi-band compressor.

@linuxdsp: Thanks! That appears to be exactly what I’m looking for.