High Pass ITB or at source?

elbandito

potential lunch winner
Hi all,

I realize that slapping a high pass on everything is, generally, a bad idea. It can cause phasing issues in the low end, leading to a mix that sounds wonky down low. This said, I'm wondering how applying an HPF at the source might differ?

For example, if I were to apply an HPF to the bass, guitar (x2), brass (x3), keys, snare, and vocal tracks BEFORE they get to tape, would I still have to look out for phasing in the low end? Or would the fact that this EQ was applied to each track individually on the way in mitigate the possible issues before they arise?

Thanks!
 
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I never record to tape, and actually never heard that it's going to de facto produce phase issues, but I definitely use a HPF in front of the preamp when the mic has one and in the preamp if it has one when I want to insure that LF content that is not part of the actual audio signal does not get recorded. I'd think with tape you'd really want to make sure you're not pushing your record level unnecessarily with content that's not part of the source. But, as a general case, that seems like a mix-time decision to me, unless it's a genre where you will 100% of the time do it in the mix anyway. Maybe.

Is phase really a problem, or does it depend on the kind of HPF?
 
I never record to tape, and actually never heard that it's going to de facto produce phase issues, but I definitely use a HPF in front of the preamp when the mic has one and in the preamp if it has one when I want to insure that LF content that is not part of the actual audio signal does not get recorded. I'd think with tape you'd really want to make sure you're not pushing your record level unnecessarily with content that's not part of the source. But, as a general case, that seems like a mix-time decision to me, unless it's a genre where you will 100% of the time do it in the mix anyway. Maybe.

Is phase really a problem, or does it depend on the kind of HPF?

I meant 'tape' figuratively. I'm actually recording into a DAW and everything is done in the box once the source gets there. Sorry for the confusion.
Gain staging isn't a problem for me... If I were to use actual tape, I'd probably track things like drums or bass to it to try to get some saturation out of the medium.

In my experience, phase can be a big problem that can lead to anemic-sounding mixes. When I first discovered HPFs I was using it on literally everything and it ruined almost every song I made, although I didn't realize it until much later as I learned more about critical listening when mixing. Back then, I used to compress and HPF absolutely everything... it was a disaster! haha.

When it comes to "types of HPF," I suppose that the steepness of the slope is really the determining factor. A 48db slope will more dramatically introduce phase than say, a more gentle 12db slope filter - at least, that's what I've discovered in my old mixes.

All that being said, I think I would prefer to use a method like the one you've described wherein I HPF my tracks at the source but of course, the problem with that is that you're stuck with what you've got. I guess I'll have to just experiment more and see what happens. :)
 
Why on earth would you put an HPF on a bass? I've no idea what your phasing problem is, or what it's caused by, but I've never had this problem as something automatic, ever? Two bass sound sources often fight with each other, but if it happens, you just deal with it as one of the normal mix issues. I suppose some styles of music are more prone to it. We had the synth 80s, and the crazy baselines and the amount of bass in a mix occasionally caused it, but to be honest, only when you had two continuous bass sources and you got the spikey sum and different phasing errors. If you use and HPF, then your bass will need boosting, defeating the point. You can lop off the bottom of other mid range sources to prevent the bass getting too murky - left hand on the piano, for example which sometimes fights with the bass guitar - but I never do it as some kind of rule.
 
Why on earth would you put an HPF on a bass?
Any number of reasons, as dictated by the needs of the song. One quick example would be to reduce the amount of unnecessary low frequency content that is generated by the act of playing the bass guitar. This is evidenced by the cone excursion on a bass cab, which is easy to see if you look at a cabinet while it's in use. There is almost nothing worth capturing below ~80hz in most situations, but that information is still captured - especially when recording direct. There is no reason why removing that content will require one to add it back later. In fact, removing this unnecessary low frequency rumble can tighten up the sound of the bass considerably all on its own. Give it a try sometime!

Check out this video for a quick visual:




I've no idea what your phasing problem is, or what it's caused by [...]
[...]but I never do it as some kind of rule.

I'm not looking for a 'rule.' I'm looking for people's opinions and/or experience with applying HPF to the source VS applying it in the box after capture. :)
 
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No idea what that video is hoping to do! I've got a 4 x 10 and an 8 x 10 cab and I can do that with the tone controls on the amp - I simply see little point in using bass cut on the bass if the musician didn't choose it as an effect, or character of their sound. If I have to record somebody slapping, then I rarely need to add the slap at the top and cut a bit of boom at the bottom because they've already done it?

I don't apply destructive eq to a sound source before I record it, because it limits options. The system can record anything you throw at it, so I am firmly one of those who record what comes in, and fiddle afterwards.
 
THERE IS no point in slapping a HPF on everything.


FIRST,
you have to figure out what has info on the track below 100hz...
it may be, that there is not enough info on the individual tracks to warrant a HPF.

the cart,
before the horse.


HPF is a tool.
to be used, when required, and not at any other time.
 
now, tracking with HPF engaged,
means you are left with what you got during the capture.
it may be, that you NEEDED some info below the frequency that the HPF filtered,
and then, you are screwed.

on close source elements like vocals,
using the rolloff on the mic makes a lot of common sense.

on a bass cab, maybe not so much.
kik, maybe not so much.

guitar cab, yea, maybe. unless you are looking for knock.
on and on, it's your job as a mixer, to figure all this out by TRIAL AND ERROR.

if you never try something for yourself, and only go by the internet troll decision making process,
then you WILL NEVER KNOW.
 
THERE IS no point in slapping a HPF on everything.

HPF is a tool.
to be used, when required, and not at any other time.

now, tracking with HPF engaged,
means you are left with what you got during the capture.
it may be, that you NEEDED some info below the frequency that the HPF filtered,
and then, you are screwed.

on and on, it's your job as a mixer, to figure all this out by TRIAL AND ERROR.

if you never try something for yourself, and only go by the internet troll decision making process,
then you WILL NEVER KNOW.

I feel like you didn't read the OP.
I know that HPF on everything is a bad idea. I know that whatever I capture is what I've got to work with. And I know that trial and error is ultimately how I'll figure this out for myself.

The question again, is: How does HPF at the source differ from HPF in the box, if it does at all, specifically when it comes to phase issues in the low end? I'm looking for opinions/experiences with these two techniques from people who have used this type of filter in both situations.

I don't know where I've gone wrong here... I thought my original post was pretty clear. :confused:
 
No idea what that video is hoping to do! I've got a 4 x 10 and an 8 x 10 cab and I can do that with the tone controls on the amp - I simply see little point in using bass cut on the bass if the musician didn't choose it as an effect, or character of their sound. If I have to record somebody slapping, then I rarely need to add the slap at the top and cut a bit of boom at the bottom because they've already done it?

No, you can't do that with your tone controls, as your 'bass' knob is most likely either a shelving EQ or a wide Q FVM/bandaxall-style tone stack (unless you're using a Mesa head or something similar that has a built-in HPF) and using that to try to remove sub frequencies will suck all the bottom out of your bass tone. As a working bassist, this is the one and only topic that I can speak authoritatively on. haha.


I don't apply destructive eq to a sound source before I record it, because it limits options. The system can record anything you throw at it, so I am firmly one of those who record what comes in, and fiddle afterwards.
To each their own. Hopefully somebody will chime in with their experience as relates to the question I've proffered. Thanks for your input :thumbs up:
 
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What phase issues?
Not a trick question - I'm just not aware of the problem.

Smearing and various other types of changes to the tone, often due to the resultant hump that happens at the frequency corner when using steeper slopes. The problem can get worse when one applies different HPFs to multiple tracks in a mix. I haven't the vocabulary to detail it in a way that won't cause a hundred people to try to argue semantics with me but I just did a quick google and FabFilter seems to have a nice page (with examples!) about the types of problems that can sometimes arise. Check it out: LINEAR VS NATURAL PHASE ON LOW END

The article isn't exactly focused on the topic but it seems to do a decent job of giving a broad overview.
 
For example, if I were to apply an HPF to the bass, guitar (x2), brass (x3), keys, snare, and vocal tracks BEFORE they get to tape, would I still have to look out for phasing in the low end?

Ok. It depends what eq you're using.
I believe anything analog will not be linear so the answer to your question is yes, unless you're using some digital linear phase eq.
 
Low passing at the source using the mic filter is going to be less extreme/less slope than what is available in the box. On a five string bass the low b string is `30 hz and the low E is around 42 hz. So no, I would not high pass these at the source. I only use high pass to get rid of rumble from traffic or ac which I don't get often. I personally prefer using a low shelf to clean mud from tracks instead of filtering mostly because if done correctly it's relatively inaudible(as are MOST 6db per octave filters). I will use a higher slopes for an actual effect or dialog but that's about it. I am thinking that you may have been over doing the filtering if it sounded bad-when done lightly it should not really be noticeable at all. The filtered track will just sound better , more defined. If it doesn't improve the sound then it's too far up the frequency range, too high a slope or just not needed IMHO.

That being said, I usually only high pass at the source on vocals, well, not Barry White style but how often does that happen? I suppose I would if I was recording horns and maybe even on violin or viola. Not on cello or larger or any "bass" instrument. Drum o'heads , cymbals etc, all after the fact if needed.
 
I feel like you didn't read the OP.
I know that HPF on everything is a bad idea. I know that whatever I capture is what I've got to work with. And I know that trial and error is ultimately how I'll figure this out for myself.

The question again, is: How does HPF at the source differ from HPF in the box, if it does at all, specifically when it comes to phase issues in the low end? I'm looking for opinions/experiences with these two techniques from people who have used this type of filter in both situations.

I don't know where I've gone wrong here... I thought my original post was pretty clear. :confused:
I think everyone has tried to answer the question, but maybe jumped on the premise you stated about doing it to everything. Ok, you get that was a mistake.

First, the big difference at the track level, answered by many, is that you may be cutting out something that is fundamental to the source signal, if you apply a HPF at the source. So, it's really important to understand the frequency content of your source, and exactly what the HPF is is cutting, and how much. If you cut even a little of the source fundamental, you have a track that is not what was original. You might try to boost something in the missing area, but it's not the same.

Now, that, of course, doesn't mean to not use them, and that's part of your clarified question, what's the difference between ITB and something earlier. I guess it depends, but generally you don't want stuff that isn't part of the source to be something that can actually corrupt/distort the source signal, and unwanted low frequencies almost certainly have higher frequency overtones/harmonics that are going to interact with your source, as well as contribute to the amplitude of what is hitting all the components from start to finish. You may have trouble understanding why the vocal sounds low when it seems like you recorded at proper levels, when the problem is very low or subsonic content in the source signal. You can take it out ITB, but it may have already introduced other noise into your track that you cannot get out without taking part of the content you want away. In an ideal studio, you'd filter everything that wasn't part of the source. We do the best we can with mic placement and HPFs at home, but only when we can do it knowing that we're not taking away from a fundamental.

I did find this snippet (as it applies to mastering, but certainly true at the track level) about HPFs, and how a shelf might be a better choice in some places. I think a corollary (my assumption) is that when you use them, you want to be pretty precise on the cutoff frequency and slope, so they don't all end up doing bad things at exactly the same place. Doing something like engaging a hardware HPF switch (with no other controls) on a preamp and using that on every single track might be setting you up for some problems.

Your Audio Mastering Questions, Answered | Are You Listening? Season 2 Episode 7
 
I feel like you didn't read the OP.
I know that HPF on everything is a bad idea. I know that whatever I capture is what I've got to work with. And I know that trial and error is ultimately how I'll figure this out for myself.

The question again, is: How does HPF at the source differ from HPF in the box, if it does at all, specifically when it comes to phase issues in the low end? I'm looking for opinions/experiences with these two techniques from people who have used this type of filter in both situations.

I don't know where I've gone wrong here... I thought my original post was pretty clear. :confused:

the fact that you are asking this question, means you still have a lot of homework to do.

it is easy enough, to find out from equipment manufacturers, what their cutoff numbers are for built in HPF.

every mfg is going to have a slightly different methodology for how they do their circuits,
so no two will be exactly the same.

the reason for using a HPF is if there is a problem.
do you have a problem?
or are you just randomly applying HPF? based on........ what?
 
I too get paid to play bass. Sub-frequencies are our fundamentals so if I play my open B string I can suck all the B out, or not depending on the need? I just don't hear the problem you have. Sorry I can't get it? However, my comment stands - if you get phasing issues from the blend of multiple sources with bass content, then it won't matter if you treat it pre-record or post record, because the issue is being generated when they mix. Hence why I think it's best to record everything and deal with it later. If you reduce any of the bass content, if there isn't enough then you end up boosting it again - why not just record it, warts and all?
 
Hi passing is great for a track, even kicks and basses. Warren Huart has done videos in the pass of A/Bing a hi passed kick/bass and the clarity/punch that resulted from it was eye opening.

Here is an article that suggest hi passing everything at a miniminum of 60hz across the board for a heavy metal track
Mixing Metal I've experimented with this and I dug the results.

I don't hi-pass sparse tracks, or even low shelf cut if the bottom end is balanced, but any general pop/rock mix gets the hi pass treatment. most reverb/delay sends get hi passed at 500hz, kicks at 20-30hz, basses at 60hz, everything else above 100 normally, snares sometimes 150hz, overheads 800.

I wouldn't hipass any double tracked, haas effect stereo trick, delayed opposite panned impulse response, or any (mono>stereo) type tracks, instead that would be important to do on the buss. because of your phase issue thing, but I have to say. I've never actually experienced any phasing issues but I would generally never hipass for eg: kick in and out seperately, maybe this is why you've ran into problems?
 
A digital minimum phase filter will alter the phase response in about the same way as an analog filter. The difference is that you can fine tune your digital version, and you can undo it if needed.

But such phase effects tend to be fairly limited in their impact unless you're applying the eq to a parallel path.

I sometimes use mic or pre HPF when I'm especially sure I want it.
 
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