EQ mixing

Extremely Questionable (EQ) Mixing



EQ mixingI would bet serious money (Monopoly money) that the question that most up-and-coming mixers ask more than any other is:

“Should I place my EQ before my compressor — or after my compressor? 
”

If you are looking for the answer to that question, fear not, I have the answer for you …

The answer is: both.

The way I mix is to place an EQ before my compressor, and then also place another EQ unit after my compressor. 

The caveat, though, is, I’m talking about two different kinds of EQ unit.

The EQ before my compressor serves a different EQ purpose to the EQ I place after my compressor.

You see, just like your compressor — which offers: 1) the task with which it gets its name (compression), and 2) provides ‘colour’ to your tracks because of its harmonic distortion capabilities — an EQ also has a dual purpose.

Subtractive EQ

The first EQ we need to insert or instantiate is what I call your subtractive EQ.

The EQ unit that serves this function best is a band EQ, such as the stock-standard EQIII found in Pro Tools, or the Channel EQ found in Logic Pro. Your DAW will similarly have a stock EQ with bands from low-to-high frequency.

This is the EQ unit that removes (i.e. subtracts) frequencies that you don’t like the sound of in your respective track (vocal, piano, guitar — whatever it may be).

What would those frequencies be? Ahh, that’s for you to decide, but, fortunately, there are a few pointers.

The first frequency you can remove for sure — without even taking a guess at it — is anything below 50 hertz or so. This is commonly referred to as applying a ‘high-pass filter’ on your EQ unit.

A high-pass filter just means that you’re filtering out the low-end of your frequencies (50 hertz and below), but letting the higher frequencies to pass through untouched by the EQ unit — hence ‘high-pass’ filter.

The kinds of frequencies we’re talking about are things like trucks rolling past your house, any accidental kicks to your mic stand while you were recording, and other low-end sounds. Highly helpful, I’m sure you would agree.

So, that’s the first thing you do to your EQ unit. Many mixers will include a high-pass filter on their EQ unit as a saved setting, and apply that to EVERY track in their mix. That way, they know they’ll be removing all frequencies lower than 50 hertz.

The other frequencies that need to be removed are found by actually adding volume to your frequency points and then sweeping the spectrum for each band until you find nasty spots in your track.

For instance, I often discover a certain ‘tubby’ tone in vocals in the low 100s. (BTW I won’ tell you where this frequency is because: 1) it’s different on every single vocal recording, and 2) you should experiment and find the problem areas of the EQ spectrum yourself — that way, you will develop your ‘recording and mixing ears’.)

Apply the same technique to each band of your EQ unit. My EQ plug-in has seven bands, five of which offer bell shapes, so that allows me to sweep five different bands across the frequency spectrum, hunting for nasty sounds.

Once you have found a nasty sound in each band (sometimes you won’t find any, and that’s okay), you then attenuate — that means, subtract or lower the volume on — that problem frequency, so that it is less than 0 on the dB axis.

Use a tight ‘Q’ when you do this (a tight ‘Q’ means the frequency cut is narrow side-to-side).

After having applied subtractive EQ on your key tracks, you will be left with something looking like this (notice the high-pass filter and the frequency cuts where I found nasty-sounding frequencies using a tight Q):

Seize Your Music - Subtractive EQ

Congratulations! You have subtracted problem frequencies in your track BEFORE sending your audio to any compressor or other audio processing unit. 

Now all you need do is apply the same process to your other important tracks.

(Yes, this part of the mixing process is tedious, but it’s worth it, and over time you will get faster at it. It takes me less than 20 minutes tops to get through this process in a large mix session.)

Remember, you don’t have to do this process to every track in your session; only the ones that are prominent in the mix. You can also apply subtractive EQ on your mix bus and other group buses, by the way — that will also save time.)

Additive EQ

So that’s the first half of the EQ’ing done. What’s the other kind of EQ process? 

That would be what I call ‘additive EQ’.

Exactly! The opposite of subtractive EQ.

Additive EQ goes on AFTER your subtractive EQ — usually with a stock compressor to level the sound between the two EQ units.

This is where the fun is. And, let’s face it, after the drudgery of subtractive EQ, you deserve it! Additive EQ is your chance to add EQ ‘colour’ and ‘flavour’ to your tracks. To boost parts of your track’s frequency spectrum to make it stand out in what could be a crowded mix.

For instance, if your vocal needs more high-end frequencies to stand forward in your mix, boost the high-end of your EQ unit.

In terms of the EQ units that work best here, I find that — if you’re using plug-ins exclusively — analog-modelled EQ units work best.

My favourite EQ plug-in for additive EQ work is the Waves API 550B. I love it.

These kinds of analog-style EQ plug-ins (or, if you’re lucky to have them, the real-deal analog EQs) are perfect for adding harmonic colour … flavour — whatever you want to call it — as well as boosting an area of the frequency spectrum you want to bring out in your instrument.

As you can tell, your additive EQ model is different — it’s broad-brush strokes, not surgical like your subtractive EQ unit. You’re adding ingredients now, not removing them like you were with the subtractive EQ.



After having applied additive EQ on your key tracks, you will be left with something looking like this (notice the EQ boost at 1.3k):

Seize Your Music - Additive EQ

Subtractive vs Additive

So, there you have it: subtractive EQ vs additive EQ — and the importance of using both to create tracks that sound great.

For what it’s worth, here is a screenshot of a typical channel, employing subtractive EQ, a stock (non-colour) compressor for more level, then an additive EQ unit, followed by a ‘colour’ compressor for even more harmonic goodness (click on the image to zoom).

Seize Your Music - EQ channel strip

In summary:

  1. There are two types of EQ you can use in a mix — subtractive and additive;
  2. When it comes to EQ’ing your tracks, subtract first — then add.

Photo credit: Question mark sign via photopin (license)

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