How can one play an instrument in Garageband but with quarter tones instead of the usual ones?

On my keyboard I can change the scale and it works, but this is not recognized by Garageband and it seems that I cannot find how to change scale to quarter tones in Garageband.

  • I haven't used GarageBand, so this might not be the answer, but you could try looking for a "key tracking" feature or some similar name. Basically, all midi insts will default to 100% key tracking, which means every half-step move sent to the inst is rendered to sound like a half-step. If you can set it to 50% (which could be a setting of 50 or 64 depending on the unit) then every half-step sent to it will be rendered as a quarter step. An octave will sound like a tritone, two octaves will sound like one octave, etc. Worth a look, but I don't if GarageBand has the feature in its instruments. May 2, 2015 at 18:12
  • I recognize the number 64 from my keyboard. Do you mean I should change those numbers in my keyboard? That could probably work but there has to be a faster and smoother way to fix this problem. May 2, 2015 at 18:48
  • 1
    No, 64 is just a number and will show up in any number of places, especially with MIDI, since most MIDI parameters take values up to 127 and 64 is the halfway point. I'm talking about a setting on the software synths or virtual instruments you're trying to control in GarageBand called "key tracking" or something similar. If you can set the instrument to only track the keyboard at 50% it will produce quarter-tones. May 2, 2015 at 19:12

2 Answers 2


GarageBand is a bit limited compared to Logic Pro X, but there's a hack that you can use. It's sort of cumbersome though, but it should work. Essentially, you're going to create 2 software instruments and add the AUPitch plugin to one of them detuning it by a quarter tone (up or down, doesn't matter).

  1. Create 2 tracks (of the same instrument)
  2. Move to one of the two instruments and click on the smart controls button
  3. Click on the i to show the inspector
  4. Scroll down on the inspector until you see Audio FX and click on a slot to add an effect
  5. Go to Audio Units -> Apple -> AuPitch
  6. On the Pitch control, double-click where it says 0 cents and change it to either 25 cents or -25 cents

The "cumbersome" part of this method is that you'll have to record notes separately on each track and then play them together to get the desired effect.


If you have a hardware instrument with quarter-tone support, you can certainly record audio from it into Garageband. However, none of the virtual instruments in Garageband will support quarter-tones played from a MIDI controller. But within Garageband, you can use any virtual instrument that uses the AU (Apple Audio Unit) protocol. If you can find a third-party virtual instrument that supports and provides the scales with quarter-tones that you need to work with, you can figure out how to make it work in Garageband.

  • Yes my keyboard have this function where you can change the tones to make it sound middle eastern, but somehow I failed to make garageband recognize that. Jul 14, 2015 at 9:32
  • Garageband will not be able to interpret quarter-tone MIDI signals coming from your keyboard. But Garageband can simply record the audio output from the keyboard, through an external audio-to-USB interface. So if the quarter-tones are so important to you, why not do that?
    – user1044
    Jul 15, 2015 at 0:20

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