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HPF on microphone, preamp, or when mixing?

Discussion in 'Microphones' started by took-the-red-pill, Jan 22, 2016.

  1. took-the-red-pill

    took-the-red-pill Active Member

    Which is best-or is it situationally dependent?

    Why?

    Have at 'er.
    K.
     
  2. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Well each HPF is gonna have a different corner frequency and slope, so it is situationally dependent. Also depending on the mic the filter may alter the sound in other ways besides just the intended purpose.

    My feeling is get it right to tape. Make up your mind while the moment is inspiring dammit! :) if your pretty sure you don't need the low end, or as much of it, I do it at the mic, or the pre. There's no need track stuff only to use cpu power to take it out and possibly degrade the signal due to negative effects from plugins.

    The pre is generally a little easier to compare while the artist is playing. Otherwise you just track a few bars or lines with the filter engaged and not engaged in the mic.

    Some mics the the Akg 414 have a selectable HPF with different frequencies the xls goes from 40-160 I belive in a few increments.

    Generally the less unecesaary low end the more headroom and power left over for what you do want. On a micro level this probably isn't significant.

    Especially w plug-insall HPFs are not equal and often times are audible in other ways. Particularly waves basic eqs are pretty nasty for that purpose. The waves ssl channel strips HPF, however is very transparent to my ears, and is continuously variable as far as frequency selection. Channel strips plugs in general seem to do a more crisp job of preserving the sound with various things engaged/bypassed than stacking individual plugins.

    Also, when mixing I find that shelving things out can have a more 'natural' effect than completely removing, but it depends on what it is. I tend to use a bit more HPF than I used to.

    I'm sure Donny will chime in, I know HPF filtering is a huge part of his rec/mix style.
     
  3. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    I see one important situation where you want to use an HPF on the mic or the preamp. It is if you have a compressor in your signal chain going to the converter.
    Since compressors react more on low frequency content, the results would be very different.

    Most of the time, my chain is mic - pre - converter, so I will use HFP only when I'm sure no content below the cutted frequency will be needed or produced by the instrument.
     
    kmetal likes this.
  4. Boswell

    Boswell Moderator Distinguished Member

    A simple rule that works 80% of the time is HPF on vocals, not on instruments.

    HPF is not like an EQ filter; it's a much more gentle roll-off, so lower frequencies can still be heard. Using an HPF right at the front end of a vocal channel reduces the problem of breath artifacts causing unwanted baseline movements or triggering compressors unnecessarily without it incurring appreciable change to the vocal line itself.
     
    Sean G, kmetal and audiokid like this.
  5. DonnyThompson

    DonnyThompson Distinguished Member

    HPF on a DAW's filter can be as gentle or as dramatic as you make it, ( depending on the fliter) But as Bos mentioned, the HPF on most mics usually uses a much gentler form of roll-off ( -3 to -6db) than an HPF on an EQ does, of which, some can slope down faster at -12, -16, and I've even seen some that offer the slope of a cliff at -24.

    Generally, I'm of the approach that vocals are usually what needs HPF the most; sometimes higher range acoustic instruments, sometimes guitar amps, and I say "sometimes" for these things because a lot of it depends on the mic that is being used, the mic's placement in relation to the sound you are after, and the environment where the recording is being done.

    The second reason I'll use an HPF - and Marco beat me to it - is if I'm using GR in the signal chain... and he's mentioned why, because kow end frequencies are compressor magnets - meaning that compressors grab low end the most.

    And while I do use HPF quite a bit as Kyle mentioned, I use shelving probably just as much. Like the HPF on a microphone, it's a gentler slope and not quite as dramatic as what you'd find on a typical filter.

    But I'll also use LPF, too, if I'm tracking bass guitar or bass synth or kick; it's probably just old habit for me, as this was the way I was taught years ago; to capture the sound as accurately as possible at the source, as opposed to just throwing a mic on something and the doing the "fix it in the mix" thing.

    And, if you don't have to commit processing and system resources to a track, why make it harder than it should be?
    A lot of this comes with time and experience, knowing what mics have which characteristics, and what to expect from a mic setting on a particular source, after doing it a lot over time.

    IMO
     
    kmetal likes this.
  6. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    Thing is, there is a school of thoughts that will HPF everything except bassdrum and bass. Altought, it's not a mistake, some will apply that to an extreem as a rule.
    I'm not gonna say rules should be broken but we should be ready to bend them if the source and the song needs it. You may like the LF in the overhead or the room mic and decide to keep it or even enhance it with an eq. If you work a voice guitar of voice piano song, hpf will kill a great part of the LF that you should keep.
    I don't want to sound like a broken record but, our ears should surpass any rules. If it sounds right who cares !! ;)
    Of course, if somebody brings me a 128 tracks song to mix, I'm sure a lot of HPF will be done ....
     
    kmetal likes this.
  7. took-the-red-pill

    took-the-red-pill Active Member

    Thanks gents. Good information.

    However I'm seeing here that I should have been more specific. I'm trying to find out if generally a HPF in a microphone is of the same, better, or lesser quality; or if there is a good reason for engaging the HPF in either the mic or the pre.

    Sooooooo....

    Let's say I am recording a vocal, in a song that will be a dense mix. I know I don't need the information down there. So I've decided I'm going to HP it. Let's say I have an AT 4050 mic(12dB @ 80). And let's say I'm running it through DAV BG1(12dB/Oct. at 68), as they have more or less similar characteristics. I don't have an outboard comp, so I'm going mic->pre->box.

    Would I be best off:
    a)engaging the HPF on the mic?
    b)engage the HPF on the preamp?
    c)What the hell, engage both?
    d)Either, because the mic HPF and pre HPF are going to be of the same quality, neither adds nasties.

    Scenario two, I'm recording drum overheads with SM81's(6dB or 18dB HPF). I have mics on each of the toms, so I've decided I don't need the low information on my OH's(whether or not you agree with that decision is not relevant to this question). Again, I'm using the DAV BG 1.

    a)engage either HPF on the mic?
    b)engage the HPF on the preamp?
    c)Engage both?
    d)Either, because the mic HPF and pre HPF are going to be of the same quality, neither adds nasties.

    Cheers
    K
     
  8. DonnyThompson

    DonnyThompson Distinguished Member

    If you want the greatest amount of hi pass, use whichever is going to offer the greatest slope.
    It's not going to hurt anything to engage the HPF on both, if that's what you're asking.

    Personally, I prefer to have the hi pass at the source. But it depends on what degree of filtering I'm after at the time, and in relation to the specifics of the mic(s) I am using, on what source and in what type of environment.

    I do question using an HPF on drum overheads, but since you seemed to suggest feeling as though this isn't relevant to this thread, I won't expand.

    IMO
     
  9. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    I'd start w the mics HPF and see if it works. I don't see a point in a mic passing along info that's gonna get cut out in the very next piece in the chain. Getting it right at the source makes mixing easier.
    I also question the use of HPF on overheads but will be quiet about it.
     
  10. Kurt Foster

    Kurt Foster Distinguished Member

    if it's a modern style daw mixing /production itb, then hpf'ing at mix leaves the most options.

    if i'm going to mix it then i like to build the mix as i track. so i hp at tracking if i think it needs it. it's a different workflow from how it's done now .

    i suspect it's because; 1) often someone else does the mix, so you need to leave the options open. 2) the difficulty of making multiple round trips to processing and then printing it while tracking while holding down latency on limited daws itb, makes that approach almost impossible. you need a lot of conversion and a console to do it that way.

    one reason some prefer tape and consoles over daws. it's not just about the sound. it's the workflow too. it's a lot easier to build a vision or make decisions about something if it can be tweaked / mixed it as it's tracked.
     
    kmetal likes this.
  11. DonnyThompson

    DonnyThompson Distinguished Member

    Solid points, all, Kurt.

    I'm willing to concede that this may be a big reason as to why I generally prefer to filter at the source; it's become second nature to me, because that's the way I was originally taught. Call it "habit". LOL

    I'm also willing to concede that this might not always be the best way in more modern production workflows, although for what I do, I think it still serves me well.

    IMO
     
  12. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    I think getting it right at the source is timeless. It's just good recording technique. Even in modern interviews w big time mixers you still always hear them say "the tracks I got were great..."

    I think the difference now is twofold- the shear number of tracks which are given (which used to be the producers job) to the mixer to do what he wants, and the idea of sound replacement and samples. MIDI and vsti makes it easy to completely restructure elements of a song like keys and drums, and also add tons of harmonies.

    While I think technique with micing and tuning are lacking today, I think it's arrangement and performance that are really not getting done at the source. I think those two qualities are lacking at the source more so than mic technique. It's fairly easy to put a vocalist 6" away from an mxl (;))or a 57 an inch off an amp. I think that performance and general songwriting and arrangement is what we hear 'not right' at the source today.

    I guess I'm old school for because I tend to do a lot of the things y'all do and I'm a generation or two behind.
     
  13. took-the-red-pill

    took-the-red-pill Active Member

    Thanks again gents. It's becoming apparent that this falls under the "personal preference," category. I think I'm inclined to take the kmetal approach and get it out of the way as early as possible, that is IF it is in fact, in the way in the first place.

    As for those OH's being HP filtred, I was just trying to create a possible scenario, not cause a ruckus. I'm not necessarily sure I'd even do it. So that's okay, y'all can comment on it.

    I'm a "the kick is king in the low end, because it's only doing one note, where's the bass is moving all over the spectrum," kind of guy. So believe it or not I have HP'ed a bass guitar and found it to be very pleasing. That might get me voted off the island even faster than doing it to OH's, he he he.


    All in good fun

    Cheerios.
     
    kmetal likes this.
  14. DonnyThompson

    DonnyThompson Distinguished Member

    The reason I don't generally like using HPF on drum overheads, is because the reason I'm using OH's in the first place is that I'm looking to capture the sound of the entire kit - not just the cymbals. For what I do, my style of production, I want the OH's to be full range, because I want them to capture the sound of the whole kit in a given space. But, the room you are tracking the drums in plays a big part in this, too.

    This would be a prime example of a moment when I would use an HPF afterwards during the mixing phase, instead of at the source while tracking.

    If I were recording just cymbals, then I'd approach it differently, and engage a HPF on the mic(s), depending on the size of the cymbals and what the cymbal part was doing. If it's a small crash, then yeah, I'm gonna be rolling the lows off pretty high; but if it's a cymbal swell (roll with mallets) on a bigger cymbal, then I'd set the filter lower, because I want to capture more of the resonating and building lower frequencies between the cymbal and the room, so that it's more full range. Cymbals are a complex soup of multi-harmonics and overtones, and you don't always want to lose that sound, which can happen if you have an HOPF set too high.

    There are some engineers who HPF everything above 80hz - 100Hz, except for kick, bass, some synth patches, tympani's, and lower piano notes, etc., Geoff Emerick, who was one of George Martin's right-hand men on The Beatles recordings at Abbey Road, is - or at least was at one time - one of these types of engineers, and I'm pretty sure I remember reading somewhere that it might even be because that's what Sir George wanted him to do.

    I don't use HPF to that degree every time, I'm not that religious about it. There are times I prefer shelving, with a much gentler slope, and there are other times when I won't roll off anything at all. I use LPF a lot, too, which isn't as commonly discussed as HPF'ing. I think it's just as important to get rid of frequencies that are above the natural reproduction of an instrument's inherent range as well as below it.
    While higher frequencies won't hog a compressor's detection circuit the same way that lower frequencies will, I still don't want anything on a track that's not supposed to be there - so on things like bass guitar, I'll roll off everything above 4k or so ... lower if there's no "slapping" involved, and I usually roll off ( or LPF) electric guitars above 6k - or even sometimes as low as 3k. It all depends on such a variety of factors, that it's impossible for me to say that I do one thing the exact same way every single time, because each situation is different.

    IMO

    -d.
     
    kmetal likes this.
  15. Boswell

    Boswell Moderator Distinguished Member

    This is an interesting thread, but let's not forget that the point of applying HPF at the source (i.e. before the pre-amp) is to reduce the amplitude of unwanted low-frequency components without having a major effect on the frequencies associated with the intended signal source. "HPF at the source" can be use of the HPF built-in to a pre-amp, or it could be applied by a switchable roll-off on the microphone itself. I have seen people use the microphones's HP switch and then apply the mixer's HPF, but doing that tends to produce a rather thin but muddy effect, as it generates series single- or double-pole filters and therefore unpleasant phase shifts.

    The type of program-related low frequencies that you would want to exclude from a vocal track might be feedthrough from a kick drum or bass guitar amp, and those nominally unrelated sources could include vocal pops, air con, motor rumble and cable handling noise.

    I would not use source HPF for frequency-shaping in the mix, for example, to help separate kick drum and bass guitar. That's what the EQ sections are for, where there is much better control of both frequencies and (indirectly) the phase of the signals in the channels.
     
    kmetal likes this.
  16. took-the-red-pill

    took-the-red-pill Active Member

    Yes, this is an interesting one. I'm learning tons.

    So Boswell, you've at least answered one of my questions: choose mic or pre, but not both.
     
  17. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Yup me too. Most drummers I've dealt with don't need any help with getting the cymbals heard. In fact it's usually a struggle to keep the cymbals out of the OHs. LPFing and eq can help this, but at the expense of crispness and definition on the kit, particularly the snare.

    I actually have never mic'd the cymbals separately. Maybe I should try one day.
     

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