# Audio Engineering: EQ and how to do it (or "shoveling out the mud")



## protocollie (Feb 12, 2009)

As I said I might do, I decided to write some tutorials for those who want them. With no further ado...

Equalization, Spectrum Analysis, and the Mixdown

*INTRO*

If you're reading this, chances are you're interested in making your music sound more professional. I mean, that's one possibility. You could also be looking for spelling or grammatical errors to harass me about or sniffing about for mistakes I've made in my engineering to pick on me for, and all of that's okay. Go for it. You can send criticisms or what have you to protocollie@protocollie.com. Go on, I'd like to hear.

One of the most important tools in a good mixdown is one that's often overlooked or completely abused, and that's equalization. An equalizer is a pretty basic tool with a lot of power. The concepts behind equalization are used in countless other effects and processors, most notably filters which are basically just glorified, single-purpose equalizers.

For those of you who are completely uninitiated, an equalizer is essentially a granularized volume control which lets you pick specific bandwidths in a sound and lower or raise the gain to either accent or eliminate the noise from your mix. Pretty much every EQ I've seen starts around 10hz and ends around 15khz. Some give you the option of rolling off extremely low or extremely high frequencies completely. There's three primary EQ types. At least skim this, in case you're using a blatantly wrong EQ setup:

_SHELVING_

A shelving EQ is the most basic type of equalizer. They consist of bands of pre-set width and simply control the gain of those bands. Typically, mixers for live sound have this sort of equalizer. They're good for rough adjustments, or if you have a sound with a lot of bassy rumble and some good treble, and you don't need the bass. Some shelving EQs also have a mid-band, and if the shelving EQ is really fancy, you might also encounter what's sometimes referred to as a 'british' EQ, which is in essence a shelving EQ with fixed bass and treble frequencies and two bonus knobs, one for midrange gain and one for the 'mid-point' of the gain boost or drop that you're trying to apply - so if you wanted to maybe quiet up the harsh snap of a snare, you could turn the midrange frequency knob towards the treble and dip the gain. If you wanted to keep the snap but maybe eliminate some thud that's making your mix sound unclean, you could turn it more towards the bass range and dip it there. If you use reason 4, this is the type of EQ you see on the larger mixer control you can mount on the rack. DJ mixers are also traditionally equipped with this sort of EQ.

_GRAPHIC_

Worthless in recording and engineering music in my humble opinion, this is better geared towards listening and playback. It's very hard to make the sort of fine adjustments you'll need to (or audition all the possible sorts of configurations you'll try while trying to pick a good EQ setting) on this sort of EQ. This is the kind of equalizer you'll see in iTunes or Winamp, or on a high-end home stereo. You can pick them out by the long row of sliders that 'draw out' the shape of the EQ curve. Don't bother with these while producing, because you have a much better EQ at your disposal, and that is:

_PARAMETRIC_

The parametric EQ should be your bread and butter in production and recording. Shelving EQs are limited but very easy to work with. Graphic EQs are a pain in the butt, have too many knobs and not enough configurability. The parametric EQ is the perfect blend of both of these, and should be your best friend. Parametric EQs consist of any number of bands, generally between 3 and 8. Sometimes, the highest and lowest bands are fixed as "shelves". For example, a 'low shelf' will either lower or raise everything past the frequency it takes effect at, according to the gain settings you use on it. Inbetween those two shelves (if they exist) are a series of 'notch' filters which have (in general) three settings:


_Frequency_ - The center frequency of the adjustment you're going to make
_Q/Res_ - Sometimes called Q, sometimes Res, this essentially determines the 'width' of the adjustment you're going to make. In general, a small Q value means a very sharp peak whereas a low one indicates a very wide slope of effect for that band.
_Gain _- The same as on any other EQ, it either raises or lowers this band.

The parametric EQ is so powerful because its bands are where you need them and as wide as you need them. They're an absolutely necessary weapon in the realm of removing mud and junk sound from your mix and you should get as comfortable with them as you can because they truly will make a world of difference to your sound.


*WHY EQUALIZE?*

So, why do this? It's simple. Equalizing lets you remove excess frequencies from your mix. If you're not familiar with how sound works, sounds on nearby frequencies interact with eachother. Sound waves will modulate and modify eachother and change the character of your sound if they're not appropriately wrangled into shape. A good example of this is the concept of 'subtraction' in sound. If you take two sine waves and phase them against eachother by 180 degrees (I won't explain this in detail here, but some other time maybe) what do you think you'll hear? The answer is nothing - the way those two waves interact with eachother causes them to completely cancel eachother out. Now, there's very little risk of any phasing occuring in your mixdown which would cause silence to come from your speakers, but this is an extreme example of a specific concept. Not keeping track of what frequencies of sound in your track are being used and eliminating frequencies that are unimportant can result in unintended modification of your sound by other bits of sound floating around.

The most common side effect of poor EQing is 'mud'. Generally, this can be described as all the sounds in your mixdown running together, with none really standing out and the sound in general lacking any serious character. You probably know the sound (whether your current tracks have it or not) because at some point when you started out at least, you've heard it. You played one of your tracks up against a commercial track and heard a significant dullness in your sound compared to something professionally engineered. A major contributor to this phenomenon is poor EQing. The good news is you can fix this, and quite easily! Let's begin.

*THE TIPS*

When you EQ your track, you're trying to create room on the sonic spectrum for all of the sounds in your track. Room in your mix is not infinite - there's limited space in which you need to fit all the sounds you're using. The bottom quarter of your track (in dance music at least) will be heavy with two sounds - the kick drum, and the sub-bass. This all happens below about 100hz, which I believe is arguable the 'start' of the bass range, though really this estimate varies depending on who you talk to. The rest of your track resides above this range, with high hats and other shimmery sounds occupying the top half of your sonic spectrum and your bassline probably teetering somewhere on the edge of this range (particularly if you have a chunky bassline with richer harmonics) and your lead and other splashes of sound (vocals, pads, whatever) occupying the rest of the space.

You may be wondering what the difference between 'bassline' and 'sub-bass' is. A lot of people tend to lump the two together, but that's a very hard thing to appropriately handle in a mix. The sub-bass is the musical, non-drum portion of your bassline that's almost completely inaudible and is mostly perceived through vibration. The 'bassline' is the stuff that has harmonic value, that has timbre your ears can perceive (it sounds like something and not just a generic noise) and that generally doesn't drop as far into the realm of shaking the room. By keeping these two sounds separate (at least on the EQ) and cutting out the space inbetween them for the kick drum to hit in, you can clean up the bass area of your spectrum significantly. You can also do this through sidechain or other methods of compression, but I'll get to that some other time.

I tend to split these out because sounds with too many harmonics don't always work well in sub-bass land, and though you can definitely get creative in that range, generally pure sine waves elicit the most pleasing, thick results. Something important to remember here is that the reason these sounds are in the realm of bass is because they oscillate very slowly. Very complex waveforms down here result in havoc - try playing a really, really low note on even a sawtooth waveform in your favorite synth if you don't get what I'm talking about. Things get very farty very quickly. Personally, as some side advice, I often take a pure sine bassline for the room-shaking portion and layer a more musical bassline an octave higher on top of it for the part of the music people can hear.

Back on tilt, though. When you're EQing, your main goal is to restrict sounds to the range of frequencies that's important to them and not let them bleed into other areas. For example, if all the important sound in your kick is below 250hz, why bother leaving frequencies above 250hz open to it? There might be some effects on the drum that cause it to reverberate in this frequency range, or perhaps it just has a 'rattle' that's not really important to your track. This rattle may be competing with, say, your snare drum for its share of space in the middle of the spectrum.

Using a parametric equalizer, set up a high shelf and slowly lower the frequency on it just until you reach the point you feel your ears are losing audible information they want to hear. Cut the gain on the shelf completely to nothing, as in no sound passes through above the shelf's start point. Do this for all things you want to live in the realm of bass only. It will clear up the sonic spectrum in the midrange and treble for the other sounds that are important to your track. This shelving concept applies similarly to sounds that should only reside in the middle or treble areas of your track - if it has no business in the bassline, roll off its bass to inaudible levels. That way, there's NO chance some stray blip will interfere with the sounds down there.

This reminds me of an important (albeit disjointed) point. NEVER raise the gain with your EQ if you can help it. I say you can help it because sometimes it is important, but for your next few mixdowns, NEVER increase the gain on ANY band EVER. Why? It sounds dodgy on an analogue EQ, and even dodgier on a digital one. If you're hearing that a particular frequency is getting really busy and say, your hats are sounding muddy? The solution is not to boost the treble on the channel with the hats - all that's going to result in is unbalanced audio and more noise. Think of your mixdown like a jar of M&Ms. You want to have each color represented fairly, like any responsible person making a jar of M&Ms. But let's say you've filled the jar up with brown and red and blue and yellow M&Ms, but you really, REALLY need green ones in it, and there's no room. The solution is not to pour more green M&Ms into the jar than you originally planned, that will just make things worse and the jar will overflow (or clip, as in the volume meter jumps into the red.) You'll have to remove some of the kind of M&M that's taking up the most space. The same principle applies to EQing.

I hope that was a good analogy.

What you do is find what sound is competing with the hats and CUT it in the area you want the hats to occupy. Maybe you have a loop in the background that's got a sound similar to a hat that's competing for that area on the spectrum. Slap a parametric EQ on the sound that's interfering with the hats. Lower the gain on a band, and then slowly turn the frequency knob until you hear a marked improvement in the clarity of the hats. Raise or lower the gain as needed so that it's not bluntly obvious, but still clears up the mud. Then turn the Res/Q knob until you find about the minimum width required to eliminate the competing frequencies. Tada - the hats are fixed! Since the hats are so busy chattering away in that area of the mixdown, you'll barely notice the absence of that small sliver of frequncy in the loop.

Again, this is not the only way to correct this sort of issue, but it should result in a marked improvement more often than not. Sometimes all it will take is the simple lowering of the volume of one channel so as not to compete so directly with the other. But if EQing is the solution you see working best, this is the best methodology for it. Boosting EQ rarely sounds good. Burn that into your brain permanently. If you really feel the need to, say, boost the highs on a particular sound? Roll off the bass on that track with a high shelf EQ and then turn the overall gain on that track up. It will have the same effect.


*FINAL THOUGHTS ON EQ*

While EQ is a powerful tool, like all things, moderation is key. Aside from the treble/bass shelving, apply it only as needed. Too much EQing can result in dead bands in the sound which sounds -really- weird to your ears. I know that lots of times I've attacked a track with way too much EQ and it wound up so thin that I had to go back and delete all the EQs, then start over again. Only do the bare mininum necessary to acheive the clarity of sound you desire. You'll eventually get the hang of the finesse necessary to do this with time, and learn to detect mud once you've cleared up enough of it to know the difference between muddy and clean sound.

If in doubt, compare your work to something professionally done. Focus on the portion of your song that doesn't sound right, then focus on that in the professional track and listen how it interplays with other sounds in the song. With enough tweaking and playing, you will eventually develop a 'sixth sense' for what to EQ and how much to EQ it - it just takes time.


*SPECTRUM ANALYSIS*

Another thing you'll use EQing for is the more granular control of the overall presence of particular bands in your final mixdown. The spectrum analyzer is an important part of this. For those of you who are unfamiliar, the spectrum analyzer is the metering equivalent of the equalizer. It shows you, on a spectrum, peak levels for each frequency instead of the overall track. This is a great and valuable tool because it can also help with muddiness, as well as get you ready to master your track.

Overall, the general rule about a spectrum analyzer on your master channel is that you want the mix to be flat - the line that denotes audio level should be fairly straight across the board. It can jump a little, but if you see a huge bulge in the bass area, your bass sounds are too loud and will make your treble sound quieter. This is especially true if you plan on mastering the track (which you should if you're serious about producing it.) Mastering requires a good quality mix-down, and part of that is even volume. If you want to see what I'm talking about, open a song from a major label in your DAW (sequencer) and run it through the spectrum analyzer. It should be fairly flat across the board. This is what you're going for. If your track is properly EQed, this is mainly a matter of jiggering with the overall gain faders for all of your tracks and getting them to match up with eachother volume-wise. If the bass is way higher than the treble, try turning down the bass, or if the overall level of the track is low, try boosting the treble.

If you don't have a properly set-up studio with reference monitors, or especially if you are mixing in headphones, this display is like your ears for the final mixdown. If you see a flat line across the analyzer and your sounds are not interfering or clashing with eachother, you've got a solid mix.

In essence, that's what's important on a basic level about the spectrum analyzer. That, coupled with your overall gain meter (the green->yellow->red vertical bars) should help you get your track around the right volume and alleviate clashing between sounds on different bands.


*THE END*

This is my first time writing something like this, so if you need more detail or clarification, want to ask a question, etcetera? Feel free to reply or e-mail me (protocollie@protocollie.com.) If you have suggestions of other things you want me to write about, let me know. I definitely have some things in mind.


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## xiath (Feb 12, 2009)

Wow, nice tutorial!  I have been wanting to get into electronic music for a while now and I have been fairly clueless on how to use the EQ.  Thanks!  Now when I get the money for programs I might have a better understanding of how to make the mud go away.


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## TakeWalker (Feb 12, 2009)

Awesome. I will definitely try futzing with the parametric EQ next time (whenever I can find a bloody program whose EQ actually _works_).


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## AxlePerri (Feb 13, 2009)

Ah, very nice! 

Mostly I have played with graphic equalizers because did not realize you more need the precision of parametric one. I stay away from parametric before, because in programs you can not input precise value into the EQ; they were all GUI knobs you adjust clumsily with mouse, with fear of not being able to reproduce settings later (yes, poor reason). Will try to find good one now. I have also always ignored shelving but now see use. And boosting EQ is bad, but it is so tempting >_> .

By chance, do you know any good free VST parametric EQ plugin that can save settings? They are always trials and buggy...

Thank you

P.S.: If you make another tutorial some time, information on how/when/where to use compression and reverb on tracks/mix could be very useful (i.e., apply on individual track? or on mix? how much? etc.).


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## protocollie (Feb 13, 2009)

> By chance, do you know any good free VST parametric EQ plugin that can save settings? They are always trials and buggy...


Not really the answer you're looking for, but settings and preset on an equalizer are 100% worthless. Equalizers are pretty much completely something you need to adjust by ear on every track uniquely and individually.

What sequencer do you use? Most DAWs come with a parametric EQ built in. I don't know much about free ones but the best parametric EQs I've used are made by Waves and Sonalksis.

One thing to keep in mind, should you REALLY need to save settings, is that most sequencers can read all the data points from inside your plugin and save presets in their own format, so look into your sequencer's ability to safe FX presets for this.



> P.S.: If you make another tutorial some time, information on how/when/where to use compression and reverb on tracks/mix could be very useful (i.e., apply on individual track? or on mix? how much? etc.). :grin:



Oh absolutely.


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## protocollie (Feb 13, 2009)

TakeWalker said:


> Awesome. I will definitely try futzing with the parametric EQ next time (whenever I can find a bloody program whose EQ actually _works_).



What sequencer do you use?


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## TakeWalker (Feb 13, 2009)

protocollie said:


> What sequencer do you use?



Right now, all I do is edit music that's been horribly equalized in the first place. I've been using Sound Forge, but for some reason, the EQ refuses to work after a while of having the program. It's bizarre.


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## protocollie (Feb 13, 2009)

TakeWalker said:


> but for some reason



The reason is the word 'sony' on the box.

I believe sound forge can use VST plugins so you might want to look up a VST-based parametric solution.


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## TakeWalker (Feb 13, 2009)

Oddly, it started doing this with my old version, before Sony took it over or whatever happened. But if it supports VSTs, well... as soon as I can figure out where to get some, I'll look into it.


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## Sedit (Feb 14, 2009)

TakeWalker said:


> Oddly, it started doing this with my old version, before Sony took it over or whatever happened. But if it supports VSTs, well... as soon as I can figure out where to get some, I'll look into it.



I've gotten a few VST's off of this site;
http://www.voxengo.com/product/boogex/

Good stuff...even there free stuff is pretty damn good quality.  I use Overtone EQ all the time for my drums, and Voxengo Boogex is good for adding some 'sweetness' to more sterile sounding tones.  I've used it to add a little extra dimension to some keyboard tracks, where I wanted to make one of the organ presets on my cheapo Yamaha PSR-248 sound closer to an old Hammond sound


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## TakeWalker (Feb 14, 2009)

Whoa, thanks for the link. I had no idea VSTs could be free (seriously, I have no idea what I'm doing). That sample rate converter could be useful too, given all the sample rate problems we have with the FA player.


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## greg-the-fox (Feb 16, 2009)

Logic's Channel EQ is my favorite kind of EQ. It was a bit hard to get used to it but once I got a good hold of exactly what everything did it improved my workflow signifigantly. I can EQ damn FAST and accurately (the analyzer helps)

I made a very quick tutorial somewhere else and I'll post it here, I'd like you to tell me if I'm doing something horribly horribly wrong. (Most likely I am)

------------------------------------------------------------------

Here's a quick tut I did in about 2 seconds. I wasn't actually EQing anything just using my imagination but this is the process I'll use and it will look something like this.

Step 1: High and low cut. This isn't really that important but you should cut your very highs and very lows to stop weird frequencies escaping. These are out of the range of human hearing or close to it but they can still cause some disruption to your mix, if there's a high sound you can't even hear and it's at high volume, think of how much space that's going to take up and limit how much you'll be able to compress your track in the mixdown. A good rule is to do this until you can hear it on individual elements, a clap really doesn't need bass so you can cut most of that out. On the final mix though it's good to keep it nice and wide.







Step 2: Hunting for bad frequencies. Bad frequencies can really ruin a sound, and even your whole mix. Sometimes it's very tricky to find them. They usually cause strange harmonics which are not easily heard. To find them create a small band like you see here, and pass it up and down along the frequency spectrum. It takes a bit of ear training but in no time you'll be able to point out where there is a bad harmonic. Usually it's louder in volume, very shrill and just plain sounds BAD.






Step 3: Lower the bad frequency. In most cases you don't want to cut it because it makes up part of the whole sound and only some parts of it are bad, some you want to keep. Just lower it in volume until you can't hear it anymore.






Step 4: Hunting for good frequencies. Good frequencies will create a harmonic but it's different from bad frequencies. Same technique though. This one's a bit harder and sometimes it's hard to judge if a frequency should be boosted or cut.






Step 5: Raise good frequency. Should give the sound a nice punch. This is very important for things like high hats.






Step 6: Hunting for good frequencies again. Yet this time it's in the bass range. Bass is trickier because headphones make it hard. If you're using monitors it's a different story but most likely you're like me and can't afford them. Just search for a warm rich tone






Step 7: (two steps in one) You've gotten the bass boost in the right place and the right level. Now you want to boost the bass overall. The rule with EQ is cut more than you boost though. So instead, lower the highs.






Step 8: Fine tuning. The treble cut you did might have lessened the impact of the good frequency boost you did earlier. Compensate for it and make any other changes.






This is just an example of how EQ can be used, it's really different each time so the key is just using your ears. Everyone has their own method too. Feel free to add anything or correct me on some horrible misconception I might have Hope this was helpful!

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NOTE: I would not necessarily do these in that order, or even all to one EQ, just various demonstrations on different things that I do. Yes I know you'll yell at me for step 5


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## protocollie (Feb 16, 2009)

greg-the-fox said:


> Yes I know you'll yell at me for step 5



yeah - boosting is a no. same effect from dropping the gain on other channels at that frequency. It's a good example of how to EQ an overall mix but it's not quite correct for an individual track within a mix for the mixdown.


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## dkmasterwolf (Feb 16, 2009)

whoa , this tutorial will help me a lot! XD ...i wanted to try it once...but ill have to wait till my computer its competely repaired X_x...


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## greg-the-fox (Feb 16, 2009)

protocollie said:


> yeah - boosting is a no. same effect from dropping the gain on other channels at that frequency. It's a good example of how to EQ an overall mix but it's not quite correct for an individual track within a mix for the mixdown.



So what if i took the gain and lowered it until that peak was at 0.0 db?


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## protocollie (Feb 17, 2009)

greg-the-fox said:


> So what if i took the gain and lowered it until that peak was at 0.0 db?



that's where it starts out? i'm not sure i understand the question.

0.0RMS is the middle of the scale and then peaks can go + or - from that 0. Most EQs specify the rolloff amount (on average 12, 24, or 36dbRMS.) If you mean the lowest point on this scale (general shown as -inf or -infinity or -[infinity symbol]), that's a bit low but if your ears dictate it needs to be cut that much then go for it. Generally I find that a cut of -6db to -8db works sufficiently for eliminating competing frequencies.

So if you do that then I guess that's what you did. The particular project dictates whether that application was correct.

To clarify for everyone, there's two major reasons for not boosting:


On a digital system, you're dealing with step waveforms rather than smooth lines, I'm not entirely sure of the process by which this happens but it's similar to the aliasing effect of blowing up a really small image. You don't have the information necessary to fill in all the blanks.
If you boost to fix clashing issues, you're constantly raising the overall volume of your track and it will become harder and harder to prevent clipping as you boost more and more things to compete with other sounds.


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## greg-the-fox (Feb 17, 2009)

protocollie said:


> that's where it starts out? i'm not sure i understand the question.



No I mean... what if I took that last picture and just lowered the master gain like so:






So that peak at approx 1k hits 0db (roughly) Then just compensate with volume on the track... would that be correct?


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## protocollie (Feb 18, 2009)

greg-the-fox said:


> No I mean... what if I took that last picture and just lowered the master gain like so:
> 
> 
> 
> ...



Nope. You're cutting way too much there. With the exception of shelves, cuts should be thin bandwidth wise. Cut narrow, boost wide. That's over-EQing up there.






The EQ should be more subtle


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