Tuning loops with stretch

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MPC's picture
Joined: September 16, 2010

I have just been re-reading the interview with Michael Upton, and am interested in the following...

"You switch stretch on and calculate different bar lengths for different pitches, so if 1.0 bar is your root note, 2 semitones up would be 0.89 bars, and so on. It’s easy to get a starting sound with the tuning you want by messing with the bar length til it’s the pitch you want, then using Mulch’s timed export function to export exactly 1 bar."

Does anybody know the calculation for pitching loops using the loop player (if there is one)? So if you have loop where the root note is 10 bars, if you wanted that loop pitched to +1 semitone, what would the bar new length have to be? I'm interested to know if there is a calculation or if it can only be achieved by ear.


jet jaguar
jet jaguar's picture
Joined: June 23, 2009

Hi there,

It's a bit fiddly and ridiculous, not sure I'd recommend it for most situations. :)

Find an online timestretch calculator. The second one on the page I linked to will do the trick. Well, almost. The problem is you have to do the opposite of what it says, so if you want to calculate +1 semitone, you should put in that you want to transpose from C3 to B2. It'll tell you you need to stretch it by 94.387%. This is what you multiply your bar length by. So if it was 1 bar it should be 0.94387 bars, if it was 10 bars it should be 9.4387 bars, etc.

Or in theory you can just know that you multiply by 94.387% for each semitone up, or 105.946% for each semitone down. So in that quote from the interview I say 2 semitones up is 89%. That's 94.387% of 94.387%. You can just keep calculating like that if you're comfortable doing so. You could even make a spreadsheet, I think that's what we did with Montano. Haha. That's rock'n'roll for you. ;)

Also, in that interview I recommended the GVST fx set - if you're on Windows you may find the GTune plugin handy as you can use it to check the pitch of a sound.


MPC's picture
Joined: September 16, 2010

That's perfect Michael, the - +1 = 0.94387, -1 = 1.05946 - calculation was exactly what I was after, thank you very much indeed!!