Hugh Robjohns wrote: ↑Tue Jul 05, 2022 12:16 pm
The master buss is waaaayyyy too late for filtering out subsonics. You've got to get rid of them at the earliest point in the chain. Otherwise all your other processing -- especially compression -- is likely to make the situation far worse than it need be.
So if you have a subsonic filter on the mic, use it. If that's not doing enough and you have a high-pass filter on the preamp, use that too... or instead.
And once the signal is in the digital domain, the very first plugin should be a third-order (18dB/oct) high-pass filter. Some filters are steeper -- analogue synth filters are commonly 24dB/octave and digital filter algorithms can often provide some seriously steep filter slopes -- but 18dB/oct is about the best compromise for effective subsonic removeable with minimal audible side-effects.
If your plugins have a linear-phase option, use that too because steep filters do inherently mess up the low-end phase response and you might not like the audible effect (it can start to sound slightly unnatural). Experiment with the high-pass filter's corner frequency (centre frequency applies only to band-pass filters) to find a setting that minimises unwanted subsonics without affecting tone.
This is good advice. If the noise really only occurs during the rasgueados, I would consider automating the EQ so that it only kicks in at those points. Because rasgueados have a large noise component, you won’t notice the filters kicking in and out. That way you avoid any negative effects of HP filtering on the rest of the track, even though they are likely to be small anyway.
It’s common for recordings to have unwanted low frequency components - are you sure everything is OK on the rest of the recording? If not, that would change the picture and leaving the EQ in place would be the best option.