Resources for the Recording Musician
March 30, 2008

EQ Low Cut

When you are mixing, do you use a low cut filter on the final mix and if so where?

For example, on a mix will you set the low cut at 50Hz, or even higher?  If so, then how do you make the bass low end audible?

Also, how do bands like The Roots get that beautiful low end without making the whole mix muddy?

No, I typically don't do ANY EQ on the stereo mix buss at all when I'm mixing.  I leave that for the mastering stage.  Even in mastering, if I think there is too much low end or subs, I'm rarely rolling off frequencies above 30 or 40 Hz maximum... and, then, only a little bit using a shelving filter instead of a hi-pass filter.  If I use a high-pass filter it will be set to very low frequencies (10 or 20Hz at most) just to remove any possible DC offset and really low sub rumble that I don't want.  If I find I need to roll off much more than that, then I definitely screwed up something in the mixing stage and will go re-visit the mix again to try to get it right.

The secret to a big and powerful low end, without it all turning into a muddy mess, is to figure out what is going to occupy that low end and then open those frequencies up for only those things that you want the low end from.  In most modern popular music styles, the deep low end is going to come from the kick drum or the bass, and sometimes both (although that's harder to do right).  For all other instruments in the mix, you can high-pass filter them up to around 100 Hz safely without really affecting the sound too much, which will leave the frequencies below 100 Hz to be used by the kick drum and bass exclusively!

If you want that chest pounding thump out of your kick drum, then that's going to be around 50 to 60 Hz, and you may want to emphasize that a bit if there isn't enough of it there.  That means, however, that you'll probably want to filter out your bass guitar or bass synth in that same frequency range so that it's not competing with the kick drum down there.  You can emphasize the bass at closer to 80 or 100 Hz to give it some low end power, if needed, while not conflicting with the thump region of the kick drum too much.

The trick is really to get the kick drum and bass to work together to give you the impression of a full low end, but without becoming too muddy.  This is certainly one of the harder parts of a mix to get right, and you really need monitors with an extended low frequency response, and a room that's properly treated to let you hear those frequencies accurately, or else it all just becomes a guessing game.

Also, don't listen to the bass in isolation when you are working on the EQ!!!  That is a VERY common mistake!  If you make the bass sound big and full on its own, I can almost guarantee you it's going to turn to mud once you add in guitars and all the other instruments in a typical pop/rock mix.  The bass should only be made to sound big and full on its own if there are sections where it's the only instrument playing (besides the drums).  As soon as other instruments come in, I can guarantee you're going to have to thin out the bass and emphasize some of the higher frequencies in the bass if you want it to cut through a dense mix and still be heard.  If you bring out the harmonics of the bass, you can totally remove the fundamental frequency, and our ears/brain will still fill in that fundamental, as if it were still there.  That's a psychoacoustic effect that many bass maximizer type plug-ins use to make it appear that there is more bass than there really is... they boost, or generate, the harmonics of the bass, which fool or ears into hearing more bass and feeling like you have a big full bass sound in the mix.  This also helps out with playback on small speakers that don't have good low end response.

In most good heavy rock or metal mixes, if you solo the bass sound, it will sound quite thin and wimpy on its own, but put back all the guitars and everything else, and it sounds right!

Of course, if you're dealing with music that's very sparse, such as some RnB and Hip-Hop stuff, where there is maybe just one other sound playing against the bass and drums, then the bass can be a lot fuller.

It really just takes a LOT of practice and experience, and listening to your mixes on many different systems, and eventually you'll get it sorted out!

Check out the recording articles on this site for an article called "3D Mixing and the Art Of Equalization" for more about using EQ to carve out space for each instrument in the mix.


I have a follow up question.  you wrote:

If you want that chest pounding thump out of your kick drum, then that's going to be around 50 to 60 Hz, and you may want to emphasize that a bit if there isn't enough of it there.   You can emphasize the bass at closer to 80 or 100 Hz to give it some low end power, if needed, while not conflicting with the thump region of the kick drum too much.

Do you ever place a low cut on the bass or bass drum just to take out the low rumble or do you leave it naked to pick up some fullness?

Thanks for your patience and I really enjoyed the article you referenced me to.

Yes... as I think I mentioned in my longer post above, Bass guitar will often sound very muddy in a full mix with lots of other guitars and instruments, and so I will have to thin it out quite a bit, and boost, or add, some of the upper harmonics to get the bass to cut through without making the mix a muddy mess.  The process usually involves rolling off a certain amount of the low end of the bass with a low shelf filter.  Sometimes even a high-pass filter if needed... but, usually a certain amount of cut/reduction with a low shelf filter does the trick.

If you do have a source that has a lot of sub frequencies that you don't want or need in the mix, then you definitely can use a high-pass filter to remove the really low frequencies (30 to 40 Hz and down).  That will get rid of rumble, as well as any DC offset, or other low frequency anomalies that may be sucking up power in the mix and causing weird things to sometimes happen.  A lot of times you can't even hear those very low subs unless you have a REALLY great subwoofer that goes down to extreme low frequencies... so, if you think you may have those on a track, it's good to filter them out.  You can use a spectrum analyzer to see if there is anything weird happening down below 30 Hz.

Depending on which instrument you want to occupy the lowest frequencies, sometimes you may want to roll off some low end of the kick drum and let the bass occupy those frequencies.  It really depends on the style of the song and what you are going for.  In general, there shouldn't be a whole lot of really deep subs on a kick drum anyway unless it's an 808 style hip-hop kick drum that was generated with a really low frequency sine wave or something.   Again, you usually get that chest pounding thump at around 50 or 60 Hz, and so you really don't need any really deep frequencies on a standard pop/rock kick drum (but you might want them for rap/hip-hop and RnB type music).  However, be careful when cutting low frequencies since most EQs and Filters have a slope to their EQ curve that extends quite a ways past either side of the cutoff or center frequency.  So, if you do a huge low cut at around 30 Hz, you'll definitely be pulling out some frequencies at 50 and 60 Hz and beyond, depending on the steepness of your EQ/Filter curve.

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