Why EQ can damage low frequencies

Post by distilled noise

I make house music, I share tips for house music producers on YT and Patreon.

September 30, 2021

In today’s first post on the channel, I want to share this video I have found on You Tube. It explains very well how EQ changes phase of sounds and how it can degrade the quality of your sounds, if not used correctly. On the other side it shows how Linear Phase EQ’s preserve the quality of the sound.

Why am I sharing this and why do I think it’s important?

I am giving a lot of tuition lately (click here if you are interested in having tuition with me) and I am starting to see the most common errors people do. One of these is the way people cut low frequencies with Ableton stock EQ Eight: using a sharp low cut around 30 Hz or so (frequency can change) on kick and bass.

If you watch the video above, you will understand that doing that with a Zero Latency kind of EQ (like EQ Eight) can damage your sound.

Now in the video example the effect is not really that audible, but if you try it yourself and solo your kick you can really hear that the sounds change in 2 ways:

it loses a little bit of the power;
it gains some low resonances even if your initial idea was to cut low freqs.

These effects are more or less audible depending on the kick you are treating, and also depending on how sharp the cut is (how steep is the curve).

It is also much more audible when you cut sounds that have low frequency content (basses and kicks) and when the cut is happening at low frequencies.

I’d say that if you cut above 100 Hz this effect is negligible.

Being low frequencies and kick punchiness so important in electronic music, I’d say this is an important thing to be aware of.

What’s the solution?

If your only EQ is EQ Eight I’d rather do Low-Shelf curves instead of Low-Cut on the lows (again when eq-ing basses and kicks; for higher frequency cuts you can use low-cut curves). Or use the less steep low-cut curve, not the “x4” one. Always set the cut frequency lower than the main frequency of the kick or bass (the louder one), to reduce resonances.

Eq wrong low cut — Don’t do sharp cuts, especially close to the main frequency of the kick.

This is a little better. But even better is using a Low-Shelf curve.

If you have an EQ with the Linear Phase option, like Fab Filter Pro Q3, when doing low cuts, always switch on that option. I suggest to do it when you have finished producing the track, so in the mixing stage. Linear Phase will infact add latency and it could be annoying when you have to record external instruments or play with midi keyboards.

In conclusion, always be gentle when eq-ing low frequency content sounds, even with Bell curves and Low-Shelves. If you have to go hard with cuts, prefer Linear Phase Equalizers, but if you have to go hard also with boost and cuts with bells to make that sound good, maybe it’s better to change sound 🙂