Pitch calculator for loops

Elektron Gear Digitakt
1

I just got a DT and have started (of course) saving all my loops with the bpm in the name, btu would be great to be able to calculate on the fly how to get the loop in sync with whatever else is going on. This so that I can improvise with breaks loops without having to by-ear them in front of a crowd.

Does anyone know of a phone app (ideally Android) that can calculate pitch change in semitones from bpm changes?

I’m aware of the trivial level of maths involved, but phone calculators don’t tend to have logs, and also I would like to be able to do this calculation with as few button presses as possible - see this link:

http://www.thewhippinpost.co.uk/tools/tempo-pitch-calculator.htm

2

(new_bpm / original_bpm) * 12

Make the result negative if new_bpm is lower than original_bpm.

1 Like
3

What if you don’t know the BPM of the loop?

Any suggestions for beat detection???

4

You’re sure of that? :slight_smile:
If you divide a positive number by another positive number, it is still positive.

To find bpm one semi-tone above, you have to multiply by 2^(1/12)=1.0594630944

X semi-tones above : 2^(1/12)^X

12 semi-tones above : 2^(1/12)^12 = 2
7 semi-tones above : 2^(1/12)^7 = 1.5

5

Pretty sure.

You’ve flipped the problem on its head. It’s about finding the semitone difference between two bpms, and not about finding bpm difference between semitones. you need to find the ratio between them and multiply by 12 to get the real value you need to put in. Yeah it could still be positive hence I said you have to make it negative if new bpm is less than the original.

6

Sorry, maybe I miss something, but it doesn’t to work with your theory :

New bpm : 240
Original Bpm : 120

240/120×12=24 semitones, instead of 12.

You’re right, I flipped the problem. I have to reverse it, didn’t find yet. :slight_smile:
240/120=2^(1/12)^X
X= ?..

Count beats during 1 mn. :thup:

7

Haha very funny…

Yes I could count but I cant do decimal places and it’s certainly not precise enough to sync to other gear!

is there an app or something else everyone is using for tempo detection???
(and I don’t use a DAW…so that’s no good for me either…)

1 Like
8

Reverse (not totally sure) :

Y=New Bpm / Original Bpm = (2^(1/12))^X

X = ln(Y)÷ln(2^(1÷12)), in semi tones.

9

Octatrack do it. :wink:
(in audio editor, with selection)
Search for bpm detection software…

10

Guys, as discussed in many other threads, the correct formula is pitch_change = 12*log2(desired_bpm/original_bpm)

For best/simplest derivation, http://www.birdsoft.demon.co.uk/music/samplert.htm (given linear relation of sample rate and bpm, and cents and semitones)

2 Likes
11

Our answers are equivalent.

12

Yours seems easier to type ! :thup:
I don’t remember logs, I have to go back to maths.

1 Like
13

take a mpc live, it detects the tempo :stuck_out_tongue_winking_eye:

14

Sorry to be annoying - I’m still after a convenient app or other method for doing the maths super quickly (rather than the maths itself…)?

15

This?

http://www.thewhippinpost.co.uk/tools/tempo-pitch-calculator.htm

16

I meant in a laptopless/internetless setting (eg during a gig)

17

I tried to make it work offline with my smartphone without success, maybe possible with a “site downloader” (don’t known the name in english).

18

Buy a scientific calculator !

19

I found one app ! :thup:
Didn’t search a lot. :wink:

Music Tools
Soundcare

https://play.google.com/store/apps/details?id=com.soundcare.smt&hl=en

1 Like
20

Thanks so much! Will get this now.