Add Bottom End to your Kick Drum in Logic Pro & Pro Tools

Not enough bottom end in your mix? Kick drum a bit weedy, thin or disappointingly lightweight? Using Logic Pro's SubBass plug-in is a well documented method for synthesising very low frequencies where  

Not enough bottom end in your mix? Kick drum a bit weedy, thin or disappointingly lightweight? Using Logic Pro's SubBass plug-in is a well documented method for synthesising very low frequencies where none previously exist, but its use is fraught with the danger of creating multiple clashing frequencies which can cause havoc and potentially wreck a mix with a mess of low end, some of which can't even be heard, unless you have monitors the size of a house. This article shows you how to double the kick drum with a pure sine tone (no harmonics to complicate matters) whose frequency you can control, in both Logic Pro and Pro Tools.

In Logic Pro:

Step 1: The Test Oscillator

There are two easy ways to access a pure sine tone in Logic Pro. The first is to use the EXS24 sampler with no sampler instrument loaded, but this requires MIDI note information to play. The second is the Test Oscillator, a handy gadget designed to test the response of your monitoring system and the acoustic properties of your listening space. When you load an instance into the input slot of a Software Instrument Channel's I/O (Utility > Test Oscillator) be prepared to reach for the volume control as, unlike a regular instrument, it just plays without being asked to, and in this case that is why it is so useful.

Step 2: Opening the Gate

Insert a Noise Gate plug-in on the same channel as the Test Oscillator, then connect its side chain input to the audio track whose kick drum track you want to double. Adjust the threshold of the Noise Gate so that it only opens when the kick drum plays.

Step 3: Tune your Sub

Check the Test Oscillator is playing a sine wave, then lower its frequency to something suitably 'subby' for your mix (around 50 to 60 Hz perhaps) - but make sure you can really hear what it is doing, as you don't want to release a mix that will destroy expensive speaker systems!

For more accurate control, you can slow down the movement of controls like the Frequency dial by holding the Shift key. Alternatively you can manually enter a value by double-clicking the Frequency field, typing a number and pressing Return. The 'envelope' of the sub tone can be shaped using the Attack and Release controls on the Noise Gate but, beware, very low values are likely to cause clicking.

In Pro Tools

The approach in Pro Tools is very similar, with one or two minor differences. Sine waves are generated by the Signal Generator plug-in - click on the first Insert slot on an Auxiliary Input track and go to plug-in > Other. Then in the second Insert slot load a Noise Gate (plug-in > Dynamics > Expander/Gate Dyn 3).

Then connect an unused bus to the Key Input. You can then send to this bus from a Send slot on the kick drum's audio track. Finally turn on the side chain by clicking the small key icon to the right of the words 'Side-Chain' on the right-hand side of the plug-in interface. Adjust the parameters of the noise gate to taste, as well as the frequency of the Signal Generator.

And that's all there is to it!

Interested in learning more about Pro Tools and Logic?

Mike has been obsessed with music software since he first saw Fairlight's Page-R, and has tracked its development through his work as a performer, composer and producer. As a writer he has contributed articles to Sound On Sound since 1999, and currently writes their Apple Notes column. As well as being a certified Logic Pro and Pro Too... Read More


Peter Schwartz
Great tip! Very straightforward approach and explanation.
Gary Hiebner
Great tip. I usually use the EXS default tone, but now I am keen to use the test oscillator plug-in
hey, cheers for the vid! i got a couple of questions which are pretty silly probably.

firstly, i set a kick drum on a track strip, standard 4 beat.
i then opened another track strip to open the test oscilator but didnt hear anything? was i meant to open it on the same strip as the kick?

secondly, if im sidechaing the noise gate to the kick drum to i need to convert it to audio first or leave it as midi?

thanks again

Mike Watkinson
The arrangements for doing this with a software instrument track (as opposed to an audio track) are slightly different.

Firstly, the test oscillator should be opened as an instrument in the input slot - it is possible to open it as an insert plug-in but this tip won't work if you do that

For the software instrument kick drum track, these don't appear as available inputs to the sidechain, so you will need to send its output to an aux channel via an available bus. So create an aux channel first, then choose a bus as its input, then connect the output of the kick drum track to that bus. Once you have connected the bus it will be available as a sidechain input to the Noise gate.

Hope that helps.
hmm that makes sense, think i no how to do the aux channel and bus, never done it before but really need to start practising it so i can send all my drums through the bus.

however im not sure how to open the test oscilator as an instrument? where do i find that option?

Open a new software instrument track, go to the I/O section of the channel strip, choose 'Test Oscillator' from the upper of the two boxes (it should be blank, the lower one being the output). Make sure you don't choose it as a plug-in from the Inserts section!
Nice! This is an old school trick we used a lot with outboard gates and a hardware studio calibration oscillator. I used this same technique in Logic awhile ago on a track for a younger artist with a not-so-deep kick drum. He was blown away with how I got the freq's so low, yet separate from the rest of the low end. The key is to use a sign wave!

Glad to see it has life in the digital world.

Thanks, Mike!

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