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EQ Basics

Discussion in 'Recording' started by Mixerman, Aug 26, 2001.

  1. Mixerman

    Mixerman Active Member

    Again, this article originally appeared on RAP. There have been 2 references in the past couple of days to it, so here it is.


    30hz super duper low, often referred to as subs up to 60hz These are dangerous frequencies to be playing with.

    50hz (hz means cycles per second) super low

    100hz pretty low and beefy, easily replicated in a 6" speaker

    250hz the start of the lower mid range, woofy, not a clean low end, sometimes to much of 250 is too thick. However, it is the range of bass
    that will replicate well in a 2"-4" speaker, so you don't want to eradicate it.

    500hz lower mid range, often accused of sounding boxy.

    750hz getting towards the upper end of lower mids. Also slightly boxy, tends to reduce clarity, however, it can also add presence in the right situation.

    1000hz or 1K (K stands for Kilo, or times 1000) This is the beginning of the upper mid range, it is a very present frequency as it is so close to
    the peak of hearing.

    2k (2000hz) This is our most easily heard frequency as humans. Too much of this and harsh will be an adjective you'll hear allot. It is
    the end of the presence frequencies. 2K has been accused of adding bite.

    3k (3000hz) Much like 2k, it adds bite. In my opinion it can be even more harsh than 2k.

    6k (6000hz) Now we leave the bite aspect, and we're into dentist drill territory. This frequency can give you a nasty headache quick.

    8k (8000hz) Now we are leaving the mid range territory, and entering
    high end territory. This is the most present high end frequency. It can be useful for brightening, without adding high end noise.

    10k (10,000hz) Now we're really into high end. This is on the lower end of high end. The addition of this can be helpful in opening up a
    sound, and reducing he coloration of a microphone, or processing.

    15k (15,000hz) This is very high end. It will often add artifacts as quickly as it will open up a sound. When you're 60, you probably won't hear this very well anymore. Or, maybe you'll hear it all the time.

    When adding high end, it is recommended to try adding 10k,12k, and 15k and decide which helps the most.

    20K Don't ^#$% with this. It's way too high.

    EQ's boost and cut more than just the frequency that is selected. You can usually adjust the amount of frequencies you are affecting with the
    boost and cut by the "Q". The "Q" adjusts the amount of frequencies that you are adjusting with your boost or cut. The selected frequency
    will get the majority of the boost, and will be in the middle of all the frequencies affected. This is called a bell curve.

    The boost and cut are usually in db increments. A typical EQ can boost or cut in the range of 12db. A great way of learning exactly what characteristics a frequency has, is to boost between 8 and 12db and sweep the frequency until you find a very offensive frequency. Then cut that frequency to taste. After a while, you'll figure out what the characteristics are of certain frequencies from this method.

    I hope this helps.

    Mixerman
     
  2. RNorman

    RNorman Active Member

    Originally posted by Mixerman:
    <snip> (sorry, no need to reiterate)
    Mixerman


    So, Mix, on your 1 kHz being the "peak" of hearing, would you be so kind as to somewhat expound on how 1 kHz works in the auditory range? Doesn't it somewhat have an impact on complementary frequencies and how you'd handle them with EQ?
     
  3. Mixerman

    Mixerman Active Member

    Originally posted by RNorman:


    So, Mix, on your 1 kHz being the "peak" of hearing, would you be so kind as to somewhat expound on how 1 kHz works in the auditory range? Doesn't it somewhat have an impact on complementary frequencies and how you'd handle them with EQ?


    1k isn't actually the peak of hearing. I said it's close. 2k-3k is what we humans hear most pronounced. But 1k is a very present frequency, without some of the harchness that is associated with those higher frequencies.

    I'm having trouble understanding the question. could you rephrase it?

    Mixerman
     
  4. RNorman

    RNorman Active Member

    Originally posted by Mixerman:


    1k isn't actually the peak of hearing. I said it's close. 2k-3k is what we humans hear most pronounced. But 1k is a very present frequency, without some of the harchness that is associated with those higher frequencies.

    I'm having trouble understanding the question. could you rephrase it?

    Mixerman


    The point is about complementary frequencies and how boosting or cutting one frequency can effect the perception of an increase or decrease of another. Bob Katz makes a pretty good presentation of the phenomena, somewhat, in his Finalizer article, but it's probably not enough. So I was wondering what your thoughts on it are, and what one could expect by making such adjustments. I mean, cutting 500 Hz doesn't JUST cut 500 Hz. It has an ancillary effect of boosting another frequency, so when we're talking about frequencies in general, I thought that it would be a good point to include this as a side note.

    Perhaps I'm just farting in the tub? <g> I admit I'm not the sharpest tac in the drawer.
     
  5. Mixerman

    Mixerman Active Member

    What you are speaking of goes into the bell curve aspect of EQ. The top of the bell curve is the frequency that is affected most by the cut or boost. The wider the curve, the more frequencies that are affected. The narrower the curve the less other frequencies are affected.

    If a vocal sounds pretty good, but just needs a little top, then a broad curve would probably be the best bet. If that vocal has a severe resonance at 2k, that comes out in spades when the singer belts, then a very narrow bell curve can be used to notch out the offensive frequency.

    Some consoles offer the ability to widen or narrow the Q, or the bell curve, and some don't have that option.

    When Bob Katz speaks of EQ, you have to consider that he is a mastering engineer, and is putting EQ on an entire mix. That's much more precarious than putting EQ on one instrument, as an entire mix will generally use the entire audio spectrum. An EQ adjustment in that situation will be considerably more far reaching than the EQ on an instrument that fits within its own smaller frequency range.

    Mixerman
     
  6. jazzius

    jazzius Guest

    also worth knowing is that eq'ing in one part of the spectrum will effect other parts. One reason for this is masking. A low frequency can 'mask' (make quieter) a higher (freq) sound. So removing this low frequency will have the side-effect of making the higher freq. louder.

    Also, applying (especially high order) filters will create phase shift (in the time domain-- nothing to do with phase as in "your speakers are out of phase"). So, for instance, a 25 hz low cut shelf could muddy the transients of your kick drum. Eq can be dangerous!
     
  7. realdynamix

    realdynamix Well-Known Member

    6k (6000hz) Now we leave the bite aspect, and we're into dentist drill territory. This frequency can give you a nasty headache quick.

    15k (15,000hz) This is very high end. It will often add artifacts as quickly as it will open up a sound. When you're 60, you probably won't hear this very well anymore. Or, maybe you'll hear it all the time.
    [/QB]
    --Mixerman

    LOL, You and Fletcher are too funny!

    --Rick
     

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