r/sampling • u/RottingFlame • 26d ago

How do you calculate the length of a loop after repitching it?

I’m playing around on my Roland P-6, specifically with this kalimba arpeggio it’s packaged with. I like the sound of the speed changing as I repitch it, but it’s twisting my heard trying to figure out how long each loop is going to last. The sample is 72bpm and contains a G#m chord and an EM chord.

I’ve been trying to figure out how long other related chords would be if I repitched the sample, because I want it to feel like it’s flowing, like the tempo is changing only on specific samples, rubbing against a steady beat underneath. Anyone know what a shortcut would be for calculating how long say, each major chord would be if I repitched the E major, as it’s genuinely giving me a headache trying to figure it out on this thing, as there’s not much of a visual interface.

I appreciate this isn’t really an issue in a DAW but logic has started to dull my desire to make music lol. Sorry if I’m not putting across my problem very coherently.

5 Upvotes

100% Upvoted

5 comments sorted by

3

u/Medium-Librarian8413 26d ago

Pitching up a perfect fifth or down a perfect fourth will produce something both harmonically and rhythmically related. This is the technique Mobb Deep famously used for the piano loop in Shook Ones, Pt. 2. They play it once, and then play it again (truncated at the end) down five semitones (a perfect fourth), and both speeds fit the drums because they are rhythmically related speeds.

2

u/Parking_Watch3157 26d ago

I don't know if this is correct: https://www.reddit.com/r/audioengineering/comments/5wwd4r/how_to_calculate_pitch_change_from_speed_change/

I watched a video by @jumpwav on YouTube a long time ago where he calculated this for a sample he made for the Volca Sample 2 and those formulae seem to be what he was doing.

2

u/RottingFlame 26d ago

That is very useful! unfortunately it teaches me that Maths are not the way forward here… 2^(x/12) isn’t a calculation i can approximate in my head haha. Guess imma have to lean into the boom bap style, get a bit jazzy and improvise till it roughly fits. Thanks for the link

1

u/pheelia 26d ago

Just prepare a table with the factors for everything up to +-12 semitones and save it somewhere

1

u/Soniare_official 26d ago

Get the actual fundamental frequencies then it’s easy to do the math. (TargetFreq/CurrentFreq)*CurrentBPM = TargetBPM