:ugeek: Thinking Cap, other Masters and :nerd: those who really know

I know that this might be a subjective question…

:arrow_right: Generally, in Mastering, below which frequencies should I filter to mono, therefore having those frequencies above it, in Stereo?

I’ve heard/read below (Hz) 90-110, 120, 350 to mono.

I may add that the track is mostly “dance-ish”, a bit rock-ish and even ambient.

:question: May I do this type of filtering (Mono/Stereo) during mixing rather?

:question: For, interest sake (I have not tried it myself yet though), what will happen if I filter certain frequencies of an instrument (eg, Bass or Kick) to mono in The Mix, but during mastering I filter certain frequencies (but not necessarily from the exact freq as in The MIx) to mono again? (Basically, therefore filtering certain frequencies to mono twice - In Mix and Master).

Your informed, and - expanded opinions are always appreciated.

summing low frequencies to mono is more pertinent if mastering for vinyl or for fixing off centre bass problems.

Generally you will have mixed most of the low frequencies to virtual center anyway, bass, kick!

If going to vinyl then it may be advantageous to sum the upper lower frequencies to mono <120Hz maybe?

Things achived in the mix are always more effective than trying to do after the mix.

Problems can arrive with phasing when summing to mono, particually with low frequecies, best caught at source and delt with there.

Mostly for modern playback there is probably not much if any advantage in mastering a good mix with lowfreq mono summing in general.