12 Replies Latest reply: Jun 8, 2012 9:23 AM by OrpheusXL
nandi Level 1 Level 1 (15 points)

i wish to experiment with several different hertz cycles like 432 hz.

how do I change the hertz in garageband?


MacBook Pro, Mac OS X (10.6.7), 17" bought 1997
  • 1. Re: how to change the hertz in GB?
    Keith Barkley Level 5 Level 5 (5,260 points)

    I assume you mean the A440 tuning standard.

     

    Garageband has no support for this. You can use pitch bending or some other techniques for simulating this, but it is a bit of a hack.

  • 2. Re: how to change the hertz in GB?
    nandi Level 1 Level 1 (15 points)

    Thanks Keith.

    Do you know if there is any software that the insturments/mic can tune to various hertz cycles?

  • 3. Re: how to change the hertz in GB?
    Keith Barkley Level 5 Level 5 (5,260 points)

    I am not sure what you mean by tuning the *mic* to various pitches, but something like Audacity can take a "real instrument" track and alter its pitch.

  • 4. Re: how to change the hertz in GB?
    Christoph Drösser Level 6 Level 6 (11,275 points)

    You can use the AUPitch effect on all your tracks to alter the pitch. You'll have to do some math:

     

    E.g., if you want to play the piano with a 432 Hz tuning, you'll have to set the AUPitch (which goes in cents = 1/100 of a semitone) to minus 31 cents.

     

    )Here's the math: one cent up is (2^(1/12))^0.01 = 1,00058 times the frequency. Divide the frequency by the same number to go one cent down. How many cents is it to go from 440 to 432 Hertz?

     

    1,00058^x = 440/432 = 1,01851

     

    x*log1,00058 = log1,01851

     

    x = log1,01851/log 1,00058 = 31,63)

  • 5. Re: how to change the hertz in GB?
    nandi Level 1 Level 1 (15 points)

    Christoph, this is very interesting.While I am mathematically challenged,I am eager to learn.

    I can divide 444 by 432 to get 1,0181 (though I dont know what the ^ means).

     

    after that I cannot yet replicate the 31,63.

    I divided 1,01851 by 100058 but that does not give me the same answer(1,01796)

     

    also what does log mean?

     

    much appreciation

  • 6. Re: how to change the hertz in GB?
    Keith Barkley Level 5 Level 5 (5,260 points)

    ^ means to raise to a power, 3^2 is 3 squared, or 3*3.

     

    log means the common base 10 logarithm function.

     

    If you don't have a scientific calculator, google can do it for you.

     

    but just use the -31 cents and you don't need to know the math.

  • 7. Re: how to change the hertz in GB?
    nandi Level 1 Level 1 (15 points)

    Thanks Keith!

  • 8. Re: how to change the hertz in GB?
    Christoph Drösser Level 6 Level 6 (11,275 points)

    I admit it's a bit hard to comprehend because frequencies don't go linear but exponentially - each octave doubles the frequency of a tone. So to go up one semitone (in an equal tuning), you have to multiply a frequency by the 12th root of 2 (or divide by this factor to go down one semitone). One cent is 1/100 of a semitone, so it's the 1200th root of 2. The calculation computes the number of cents you need to adjust from a 440 Hz to a 432 Hz tuning.

  • 9. Re: how to change the hertz in GB?
    nandi Level 1 Level 1 (15 points)

    Thanks Christoph,

    I guess I should have listend more in high school math class some 40 years ago...

    When I have time I will follow the advice here and try to learn how to arrive at various hertz.

    For now, I have started recording in GB at -31 cents.

  • 10. Re: how to change the hertz in GB?
    OrpheusXL Level 1 Level 1 (0 points)

    I have tried to use AUPitch to set each track (or also the Master track insted) to -31 cent.

    But GarageBand (latest Version) insists to reset it to -24 cent! (after reopening the AUPitch)

     

    Any ideas why od how to change this?

  • 11. Re: how to change the hertz in GB?
    OrpheusXL Level 1 Level 1 (0 points)

    Well, when I import a song into Audacity and there call the Apple AUPitch, this plugin works as it should and resamples to -31 cent. Just to let you know....

  • 12. Re: how to change the hertz in GB?
    OrpheusXL Level 1 Level 1 (0 points)

    Ha! Found the mistake in GB!

     

    The input into the AUPitch plugin is not being accepted, as long as the "Music keyboard" (Musik-Tastatur in German) is opend and visible. Closing it, everything works as it should, even with -31 cent.

     

    Good, that we talked about it!