Note: This is the original writing for an article about sound equalization. The article has since been updated with new information by a new writer. This article was written to maximize SEO results. H1, H2 and H3 are header markings implemented to that effect.
Additive EQ vs Subtractive EQ (H1)
In this article we discuss… (H2)
How do subtractive EQ and additive EQ differ?
Debunking myths about why subtractive EQ is superior.
The real reason you should use subtractive EQ: saving headroom.
What’s the best way to EQ, additive or subtractive? (H2)
One of the most used tools in mixing is EQ so it’s important EQ the right way.
But what is the right way to EQ?
With EQ, the options are either subtractive (taking away specific frequencies) or additive (boosting certain frequencies).
But which one is better?
The short answer is that it’s better to use subtractive EQ, especially if you’re just beginning to mix. But perhaps not for the reason that you would think.
There’s been a few myths about why subtractive EQ is better (“better” defined as more true to the original signal), and we’re here to sift through them with you.
The first myth is that additive EQ uses active gain, giving your track harmonic coloration
The second myth is that subtractive EQ creates less phase shift
After discussing these myths, we will come to the real reason you should use subtractive EQ: to save headroom.
Myth 1: additive EQ uses active gain, distorting the signal (H3)
This myth applies to hardware EQs, which could utilize either active components (using their own power source) or passive components (not using their own power source). In older designs, additive EQs used active components, and subtractive EQs did not. This additional voltage from the active components colored the sound, therefore making the signal less faithful to the original.
However, many subtractive EQs would then include an amplifier to compensate for the lost gain, which did require active circuitry, again coloring the sound but with a different tone. In these cases, the real claim should be that active EQs just didn’t color the sound as well as the passive EQs—and that claim is purely based on taste.
For instance, here’s Canadian music engineer Shawn Everett praising the tone of the API 550A active EQ:
“The 550A in particular is so simple that I feel like I can easily get a tone I was imagining out of them. It almost feels weaponized. Sometimes in audio things feel light and delicate, this feels like a lethal weapon; it's like a sword.”
Of course, this becomes moot point if you’re mixing in the box. But it still leaves us with the other thorny myth.
Myth 2: subtractive EQ creates less phase shift (H3)
All equalization is technically achieved through phase shift, whether subtractive or additive. The type of EQ does not make a difference. We can see this through a quick test.
1. Open your DAW and run the same audio through two tracks
2. Add a high shelf EQ at 2k with a +12db boost on the first track
3. Add a low shelf EQ at 2k with a -12db cut on the second track (it’s should sound the same as track 1 but quieter)
4. Boost the second track so the levels are the same for both tracks
5. Phase invert the second track
After step 4, the audio doubles in level.
After step 5, the signal is completely canceled out because the two tracks are identical.
We can see with our experiment that both additive and subtractive EQ create the same amount of phase shift because they produce exactly the same signal. The amount of phase shift is determined by the size of the boost or cut.
Now that we’ve dispelled these myths, let’s talk about the reason you should use subtractive EQ instead of additive EQ.
Subtractive EQ will leave you more headroom to work with (H3)
When mixing a track, the goal is to make each element fit in with the others. Imagine packing a suitcase on a well deserved trip to Thailand. You don’t just jam all your clothes in there like you’re stuffing pizza boxes in the compost. Instead, you want to fold the clothes nicely so they all occupy their own space. Folding the clothes is like subtractive EQ—it pares down your Hawaiian t-shirts so they can fit in with your speedo collection.
While you can get the same results with additive EQ (by doing the inverse boost and then cutting the entire signal level), it’s generally better to do subtractive EQ. Why?
When using additive EQ, it becomes too easy to get into what’s known as the gain wars. The gain wars goes something like this:
“I want to boost the snare a little at 400hz because it has a nice thump there… but now the vocal sounds weak in comparison so let’s boost the vocal a bit as well… but now they are drowning out the rhythm guitars. They give the whole track its groove so let’s boost that too…”
And on and on it goes…
But soon each track has so much gain that it’s clipping and causing distortion (not the good kind). And when you combine them together, they also clip the master fader, and they leave no room for the mastering engineer to work with.
The result? A bad sounding track.
The solution? Subtractive EQ.
Instead of boosting every track, try cutting out the things that you don’t want in your mix. It might feel counterintuitive, and you’ll probably dislike this method more at first. But just remember: the cuts will have the same effect as the boosts that you would have originally made!
Why? Because once your mix is done, the mastering engineer will bring the level of the whole package back up.
In other words, when you use subtractive EQ, you are boosting the parts of the audio that you like. The difference is that the boosting happens later in the process (and it may even be done by someone else). In the meantime, you don’t have to worry about clipping distortions or leaving enough headroom to work with.
Q: What are the different types of EQ? (H3)
A: In this article, we have discussed whether to boost or cut with EQ. But we have not talked about the specific categories of EQs. Luckily, we have a nice guide for just this topic.
Q: I’ve heard that you should “Cut narrow boost wide.” Is this true? (H3)
A: The reference to wide/narrow refers to the bandwidth of the filter, or the range of neighboring frequencies that the filter will affect. Bandwidth is labelled “Q” on filters. The higher the “Q,” the narrower the bandwidth.
“Boost wide cut narrow” is a common saying, and it is generally true but let’s take a moment to dissect why that is.
When cutting something out the mix, narrower cuts sound less noticeable, often because the cuts get rid of sharp resonances. In comparison, a wide cut changes the track’s entire tonal balance.
You would think that the same must be true of boosts, but that’s not the case. When you boost narrow, resonances are artificially created, often in undesirable, harsh ways. In contrast, the wide boost sounds relatively more transparent, despite changing the tonal balance of the track.
You can test this yourself by boosting and cutting with narrow and wide Qs on the same track.
Of course, this maxim generally applies to removing specific problem frequencies (resonances) and boosting for tonal balance.
There are instances in which you would cut for tonal balance as well. And there are (rarer) instances when you would want to create extra resonances.
Q: What is the best EQ out there? (H3)
A: Generally it depends on your taste and what sounds good to you. Everyone has their own favorite EQs.
Here is a guide to free EQs so you can figure out for yourself!