Low Cut Guidelines

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mattkw80

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I've spent all day today reviewing some tutorial DVD's, and mixing books, and several of them stress cleaning most tracks up with some form of low cut. (aka High Pass). One DVD even goes so far as to say this as a guide line : "You should be using at least as many low cut filters as you have tracks".

I've compiled a list of some of the 'guide line' spots in which tracks could receive a low cut. However, some sources contradict each other.

Anybody here care to comment on this, or better yet, provide their own 'rule of thumb' list of where a high pass filter should be set.

I know some of these have got to be accurate, becaue pre-amps and mics (such as the AKG C 414) have low cut's for you to use at 40, 80, 160, etc.

(Again - some of these are probably wrong, as some sources contradict each other)


Vocals @ 100 (Some sources say 150)

Acoustic @ 250

Kick Drum @ 50

Snare @ 75 (Some people say 150)

Toms @ 100

Hi-Hat @ 200

Over head Drums mics @ 150



So what do you guys think ?

So you agree with this as a general low vut guide lines ?

What are your settings for piano, guitar, bass, etc ?
 
I think for the most part I agree.
As with any generalization in targets, in always "depends" on the instrument, how dense the track count is and the actual instrument/mic combo.

I rarely cut both the kick AND Bass, usually one or the other unless there are issues.
A lot of the other targets I actually start much higher, but you are "safe" to start there.

My opinion and experience naturally.
 
Following two basic first principles - a) if it ain't broke, don't fix it, and b) don't make your signal chain any longer than you have to - I personally don't *automatically* low cut/high pass anything, and certainly don't have pre-determined frequencies based upon the instrument. I much prefer to wait for the mix to tell me what it needs and doesn't need.

That said, yes I will often wind up high passing many of the tracks I get, but I wat to hear what I have to deal with before I make any moves. There are exception times, for example, where some subharmonics may actually add some character to some acoustic instruments like guitar or saxaphone and/or when the bass may actually be a bit too muddy in that particular recording or arrangement, and I may actually wind up cleaning it out a bit in the lows rather than reserving room for it. It entirely depends upon the mix.

When I do do a lot of high passing, usually it will knee at or below 100hz; the only times I slice off higer than that is if there is a specific problem with the room or with mic pre buildup or something like that that calls for a higher knee, or if I am carving a specific sound for the instrument itself.

G.
 
I'm with Glen... I don't start hacking of lows unless there's (A) something there to hack off and (B) it's getting in the way of something else. It's VERY easy to make a very anemic sounding mix by "automatically" cutting low end...
 
I'm actually going to buck my usual trend of recommending against broder guidelines to follow in most instances and to always do what your ears tell you to do, etc.

In the case of low-cuts, I just think that 99% of the time, a mix can benefit from it. I also think there are some generic guidelines that will work in most cases. There, I said it. :D

I think most of the cuts you listed are pretty close. A few things to consider, though. 250 is quite a high starting point. Even for accoustic guitar. Just make sure it's what you want before you go around cutting out half the guitar's body.

As for the overhead and tom mics ... be careful there, again, before you go cutting the depth out of your toms. Start a little lower, and work your way up if you have to. Keep your roll-offs steep to keep things more natural ... steeper for creative effect, etc.
 
Great advice, thank you.

Glen mentioned keep some sub bass stuff - I did read that with a low track count (say, vocal + acoustic guitar only) that people will leave the sub bass on purpose, and do not low cut's considering there are only 2 instruments.

I will lower my own personal "250" guide line on acoustic back to 100 / 150, and as well, I'll watch the Tom's, Overheads, etc.

Thanks for the advice guys.

I was sort of expecting most answers to say "That's all crap" but not that I know there is some truth to the guideline, it could make mixing a little easier for me -- as I know that to this point I have always had a bad build up in the 100 to 250 area, and this could great simplify things for me.

I do listen to every track before I set the setting, so I know they really are only guidelines, and sometimes you want to be lower or higher (or not use it all) but having said that -- I just used the guide line on 1 of my songs and voila.... I can now here the bass and kick drum.
 
mattkw80 said:
Acoustic @ 250
So what do you guys think ?
Click to expand...
Yowza. That's gonna be thin. - unless you're trying to band-aid a cardioid that was right up against the soundhole. Around 60 Hz if you're going for a natural sound and want to reduce environmental rumble, around 100 Hz for strong low-note reduction.

And in a mix, high-pass is OK. But to my ear, with anything on an acoustic gtr that you want to keep sounding really natural, a high-pass filter is not transparent, no matter how low you put it. It always changes the quality of the higher range too, even if subtly.

Edit: Ah, I see the ac gtr comment in your post done as I was writing.:cool:
 
See, there's the issue... You can shelf 250 on an acoustic if it's a little boomy with no problem - IF it's a little boomy... But actually *cutting* it with a HPF -- Again, it depends on the filter. 3dB/octave? Might be fine. 6dB might thin it out a bit much. 12dB or elliptic is going to kill it - probably.

Maybe... Perhaps...
 
The low E on a guitar is 80Hz. A high pass above that as a general rule is crazy talk! If it's boomy, move the mic or change it.

Vocals, 100Hz is too low as a general rule. My speaking voice is around 100Hz. Just imagine what you'd do to Barry White or James Earl Jones!

My "singing" voice is more like 500Hz though, so no problems there :o

If in doubt . . . this is actually a good application for FFT. Look at it, find the lowest fundamental, and cut below that.
 
And for boomy low notes on an ac gtr take that you want to sound more natural, a good multiband comp carefully used is better anyway.

...than EQ
 
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I've read about the "fundamental" but don't understand it.

I do have a FFT analyzer.

How do I know where the fundamental is ?
 
mattkw80 said:
I've read about the "fundamental" but don't understand it.

I do have a FFT analyzer.

How do I know where the fundamental is ?
Click to expand...
The "fundamental" is a fancy term for the frequency of a particular note. For example, when mshilarious syays "The low E on a guitar is 80Hz" the fundamental of the low E is also 80 Hz. This is to be compared to the "overtones" or "harmonics" of that notes, which can be found in even multiples of that frequency above that (160Hz, 240hz, etc.)

There can occasionally be "subharmonics" or "undertones" of the fundamental as well; e.g the second order subharmonic (first undertone) of the low E, if it rears it's head, would be found at 40Hz, or half of 80 Hz.

G.
 
I don't agree with those guidelines to be honest. Not everything needs LC. And some of those starting points are VERY high. 100 on vox? My lowest comfortable singing note is around 65Hz (C). Obviously it depends on the voice of the singer, but 100Hz is an awfully high place to start.

I personally very rarely use a HPF on a kick. I don't always use one on the Snare, and only in exceptional cases would I use them on Toms. It all depends on the mix. (And in the case of drums, how much of the close mic sound you want contributes to how much I'd cut...)

Don't get in to the easy habit of just doing things because you always have, or someone has told you they're standard. Sure, experiment with the HPF, but don't reach for it on each channel before you've even established what the mix needs.
 
mattkw80 said:
I've read about the "fundamental" but don't understand it.

I do have a FFT analyzer.

How do I know where the fundamental is ?
Click to expand...

It's the lowest peak. The fundamental is the pitch of the note being sounded. Above the fundamental are all of the overtones. The overtones determine the timbre of the instrument or voice. For example, male vocals usually have more overtones than female vocals (usually). Richer sounding vocals have more. For instruments, flutes have few, oboes have lots. Violin has a LOT. Etc . . .

But that's not too important for this issue, we don't care how high the overtones go, just how low the fundamental is. Here is a picture of me singing one note. You can see the fundamental peak, and each overtone at a multiple of the fundamental (2x, 3x, 4x, etc). Up to about 2kHz on this note, above that the overtones get lost in background noise, breath noise, and such. But my daughter can hit fundamental notes at 4kHz! :eek: Another thing, this is just a vowel, if you watched an FFT while a track was playing and the singer hit a loud 's' or 't', you'd see a lot of incoherent energy in the 4 to 8 kHz range.

Another thing to watch for is breath pops; those will show a lot of incoherent (meaning not related to any fundamental note sung) energy in the low bass. Ideally you wouldn't have those, but if you do, first I would edit them down before the low cut. But either way, don't mistake a breath pop for a fundamental and cause you to use too low of a low cut.

Now that is just one note, if you FFT an entire track the peaks from the different notes will kinda all blend together BUT you can still see the obvious dropoff below the lowest note. On this vocal, you could safely cut 80Hz and below without affecting the actual singing.
 
Consider using a shelving EQ with a gentler slope then a strict HPF. I like HPFs for getting rid of unwanted rumble or bleed but usually when trying to tame some boomy notes I'll go with a more gentle roll off.
 
Always cover the nipple - except for the very occasional nipple slip!
Any lower & there's no point wearing it! (or your not wearing it over the point).
 
Lot's of great info here, thanks guys.

Mshilarious.... what FFT filter are you using?

It looks like the same one the guy in the Steinberg DVD's is using.
 
One interesting effect of HP on bass and particularly kick is that the intruments can actually sound like they have more bottom end when they are used than without. I attribute this to the speaker behaving more efficiently reproducing freqs that we hear in the bottom end rather than trying to poorly reproduce stuff that is less heard (10/20Hz).

Both HP and LP filters are often ignored and should be employed whenever the frequency range of an instrument is going beyond what it should be contributing to a mix. For example distorted electric guitars may have both a HP and LP filter, one to get rid of rumble or too much proximity effect of a mic too close, another at the top to remove overly bright overtones and warm up the sound.

In the case of the acoustic guitar above, 250 may be appropriate for an acoustic guitar part whose role is more of a percussive effect on top of electrics (like a lot of Rolling Stones tunes). For a solo acoustic piece though that's a bit high. That's one reason why "rules of thumb" are meant to be taken with a grain of salt, no matter what they refer to.
 
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Good thread.
I've been fighting the lo/mid mud and I've found some of those numbers to be pretty close. Except for the ac @ 250hz. I usually start around 80 and play from there.
But a good thread nonetheless. :D
 
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