K-metering on headphone

Discussion in 'Mixing and Mastering' started by MaXe, Nov 18, 2018.

  1. MaXe

    MaXe Ultrasonic

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    Hi guys,
    I am confused about k-metering. They say it gives you plenty of headroom (Obviously it gives you that since you lower the volume to make headroom!) and I really cannot differentiate it from VU-metering since both give the mixer enough headroom to mix. Why should one use K-metering? ( Don't answer with youtube videos which state the same damn sentence saying, "Cause it gives you enough headroom" )
    I have also found some articles on calibration and SPL Meter. Since I don't mix on expensive monitors and I don't have a microphone with flat frequency response to measure that white noise they talk about in first place I would be interested in knowing how I can calibrate my headphone (in which I use Sonarworks reference to handle that almost flat frequency response for me) for use with K-metering? So my question boils down to two things:
    1- Why use k-metering when there is a VU-metering(-18 dBFS)?
    2- How to calibrate headphone properly for K-metering?

    Somebody with valid knowledge please help! Enlighten me! May god bless us all :D
     
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  3. Talmi

    Talmi Audiosexual

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    To put it simply the VU meter standard was settled according to what levels hardwares could idealy handle before going into the red zone.
    The K system is something different, since in the digital realm the "red zone" is something else entirely (infinite headroom and all, which doesn't mean there isn't digital clipping). Anyway it's more related to the loudness war, preserving dynamic in the material through the way it's calibrated and it aims at standardizing levels for the different mediums available so that there is no diffrences between say songs being aired at the radio etc. It's for both the listeners ears sake and for standards purposes.
    Also they are calibrated differently in how they react, so it's not just a matter of where the dbFS level is located. Besides there are different K levels (12,14,20).
    I don't understand your question about the headphones, K system or VU is about mesuring your signal levels, it doesn't matter or know if at the endline you have cans or monitors. You choose your levels according to what medium your mix is destined to (youtube, tv commercial whatever) not according to what gear you use to monitor it on.
    Reference is for "cancelling" the frequency curve your headphone have by "design", it has nothing to do with level monitoring.

    Side note : VU meters emulation, and the - 18 dot is still very relevant today even in the digital age, since a lot of emulation of hardware available (specialy tapes emu, sat emu, etc) are "calibrated" by the devs to give their "best" result at 0 on a VU, just like in the hardware world. If you use a lot of emulations in your daw, tracking with a VU is a very smart idea, which is why a lot of people advise to do so. Setup VUMT on each of your track, aim at 0 in the VU preset, and you're golden.
    VUTM also offers the K system calibration system.
     
    Last edited: Nov 18, 2018
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  4. Maizelman

    Maizelman Platinum Record

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    1. As Talmi already said, VU is a whole other standard than K Metering (which is used to measure peak and RMS in dbFS in the digital realm). However:

    "When your monitors are calibrated with the K-System meters, 0 dB on the meters should correspond to a real-world loudness of 83 dBSPL (85 dBSPL for two channels), a reference level that has been used in the film industry for years. This calibration must be done separately for each K-Scale, since the 0 dB anchor point will be -12 dBFS, -14 dBFS or -20 dBFS, depending on the K-Scale. They key thing to remember is: no matter which K-Scale you choose, 0 dB corresponds to the same physical loudness. The difference between the scales is the amount of headroom they provide."

    2. K-Metering is used together with monitors:
    "To calibrate your monitors, choose a K-Scale and then play a single-channel, full-spectrum pink noise signal at 0 dB on that scale. From your listening position, use an SPL meter (with a C-weighted, slow response) to measure the loudness. Tweak your monitor gain until the SPL meter reads 83 dBSPL. Then, repeat the process for the other channel. Make a note of your calibrated monitor gain for future reference. Then, if desired, repeat this process for the other K-Scales."

    It wouldn't make much sense to calibrate your Headphones to 83dBSPL. :dunno:

    https://www.meterplugs.com/blog/2016/10/14/k-system-metering-101.html
     
  5. Talmi

    Talmi Audiosexual

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    Yeah cheers for those details. Didn't really mean to get technical.
     
  6. MaXe

    MaXe Ultrasonic

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    I still don't know whether I should use k-metering and how should I know my headphone is giving 83 or 85 SPL? and I still don't know why the exact difference between both VU and K-metering?
    Guys I don't want to know why I should use VU metering. I wanna know why would one prefer k-metering rather than VU? and Does k-metering have any effect on mix quality or mix result? ( Like can I make better judgements with K-metering? like doing better leveling of elements in mix? )
     
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  7. Talmi

    Talmi Audiosexual

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    They are calibrated (filtering, time of reaction) differently : the needle doesn't react the same way.
    And they have different reference scales, they can give you more or less headroom.
     
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  8. Talmi

    Talmi Audiosexual

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    Okay.
    Never mind.

    Good luck and good travel to you dear sir. :wink:
     
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  9. Maizelman

    Maizelman Platinum Record

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    ... Probably not enough Headroom between the Headphones.
     
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  10. Andrew

    Andrew AudioSEX Maestro Staff Member

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    Okay, let me try...
    By 83 or 85 SPL, I assume you mean dB SPL..
    That's quite simple, and doesn't require any calibration.
    1. FInd out what impedance and sensitivity are your headphones. You need RMS Voltage and sensitivity in dB/milliwatt. For simplification, I'll assume 600Ohm and 88dB/mW
    2. Set your audio interface to comfortable listening level, then pull out the HP jack and measure its VRMS by applying resistive load same as the HP's impedance (in this case 600Ohm resistor). This should give you good approximation of a voltage that's exciting the HP's driver.
    3. Download this spreadsheet: https://robrobinette.com/images/Audio/Headphone_Power_Calculator.xls
    4. Input the HP values into the first two fields, then fill the VRMS you measured at the audio interface under "How Loud Will an Amp Drive Your Headphones"
    5. You've got your peak dB SPL value at 1kHz
    6. Profit
    :like:
     
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  11. Talmi

    Talmi Audiosexual

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    Thanks Andrew. I'm pretty sure if he doesn't understand the k system, this one will much easier for him. :wink:
     
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  12. Andrew

    Andrew AudioSEX Maestro Staff Member

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    Offtopic comments cleared and edited.
     
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  13. MaXe

    MaXe Ultrasonic

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    Thanks to Andrew who did a good job of explaining the process of calibrating headphones unlike the others who claimed that it wouldn't make any sense. Not everybody is destined to understand things. :)
     
  14. Andrew

    Andrew AudioSEX Maestro Staff Member

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    Let's not go there, and rather let's settle on the conclusion, that your question was answered.
     
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  15. Maizelman

    Maizelman Platinum Record

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    @MaXe, to keep it short and simple. Bob Katz did not develop the K-Metering System for engineers to use it with Headphones.

    You can calibrate your headphones as long as you want but that has nothing to do with K-Metering. Could it be that you meant K-Weighted Metering? That would actually make sense in combination with headphones. It's a completely different story though, but it's very easy to mix up these two.
     
  16. Andrew

    Andrew AudioSEX Maestro Staff Member

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    I read something on the subject, but I don't get it...
    K-Meter for $49 seems to be doing what Youlean Loudness Meter is doing for free.
    Only Youlean doesn't have the "Approved by Bob Katz" sticker on it.

    How is K-Metering different from the usual LKFS/LUFS metering by R128 or BS1770 ?
     
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  17. Talmi

    Talmi Audiosexual

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    Katz insists on the calibration on the endline (db SPL) and requires that you calibrate your monitors to be efficient, also he is very insistant on leveling (compression, etc). His system isn't just about metering - according to him - but about metering, monitoring and leveling. "K (12 or 14 or 20) defines the 0 VU point (relatively to fs), the monitoring gain, and the approximate monitoring sound pressure level".
    Basically simply using the scaling like it's possible with some plugs without following his other guidelines render the system incomplete. That's why K-meter includes a calibration tool, which make it fully compliant with Katz system, I guess. :dunno:

    Edited : also they don't react quite the same in measurement. It seems Katz himself recommands Itu bs1770 for loudness measurement (https://www.digido.com/ufaqs/k-system-itu-r-bs-1770/). Although when he wrote this (a year ago) he also indicated that no one had yet implemented an ITU version of the K system. I think K Meter actually does that now.
     
    Last edited: Nov 20, 2018
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  18. Andrew

    Andrew AudioSEX Maestro Staff Member

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    Thanks @Talmi
    I sense some more reading from my end might be necessary. I assumed BS1770 is already taking ATH curves into consideration, that's why it was my choice over EBU R128, but this K-system seems to be accounting for dBFS (and possibly dBTP too), keeping all variables in check.
    I'm still quite vague on the calibration part - not everyone is comfortable driving HP/monitors into such high levels, but at lower levels, the ATH is different.
    Can you calibrate to, say 65dB SPL instead of the proposed 83/85dB SPL?

    EDIT, just read this header on Gearslutz: :rofl::rofl:
    Recommendation: Skip the K-system and use the playfully titled "T-System (click me)" instead, which is much easier to set up and gives you a lot more digital headroom, and still allows you to be compliant with the Movie/TV industry if you have that requirement.
     
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  19. Maizelman

    Maizelman Platinum Record

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    The most important difference is that K-Metering is not measured over time like LUFS=LKFS are. The K-Meter gives you a better view on Levels because VU-Meters show:
    [​IMG]
     
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  20. Andrew

    Andrew AudioSEX Maestro Staff Member

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    @Maizelman But then there's Momentary, Short-term and and Integrated, related to the time domain. Couldn't Momentary measurement be a substitute to K then (last 0.5 seconds), following True Peak and LRA?
     
  21. Maizelman

    Maizelman Platinum Record

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    Yes, I think those two are evolutionary related. :) There were some more reasons why K-Metering was/is useful. If you want a quick overview on K-Weighted LUFS I can recommend the NLE izotope insight tutorial and if you want to know what Bob Katz intended with K-Metering, have a read at his, not too long, official <AES document>.
     
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