Creating Rhythms Out Of Frequencies


The first thing to acknowledge is how a waveform works. For this we will be using a sawtooth wave being produced by one of Ableton Lives native devices, Analog.


Sawtooth Wave:





Here is the waveform is going through a series of “compressions” and “rarefractions”. Essentially it is pushing the speaker in and out really quickly to create sound and that sound is measured in Hz. We want to make a rhythm that makes musical sense out of these compressions and rarefractions of the waveform.


I will try to recreate Quarter notes 1/4, Eight notes 1/8 and Sixteenth notes 1/16 at 100 bpm (Beats per minute. So a whole note is 100 notes per 60 seconds or 1Hz)


I am starting at C-2 because, this oscillates quite slowly. It is not really a note; mostly just clicks and pops. To emphasise this I have a filter with a lot of resonance and frequency around 1kHz (1000Hz) to make the compressions and rarefractions really stick out as clicks and pops.
So step one is to find out how many times per second this note is compressing and rarefracting. One will have to print the note into audio from the MIDI and count it.


Here is one second of filtered saw waves:





So there is about half a wavelength at the beginning of the clip, and half at the end of the clip, and 7 in the middle. So I will say there is 8 oscillations of saw wave in this clip.


Formula:

So if we want 1/8 notes it is as simple as knowing that halving the octave halves the frequency.
Therefore, dropping Analog’s ‘osc’ parameter ‘octave’ to -1 will give you a C-3 (seems the midi note is a C-2 and it wont go any lower) and in theory will give you half the speed of what we have. which is 1/8 notes. (again it is not perfect so printing it to audio and warping it will fix that).


Dropping Analog’s ‘osc’ parameter ‘octave’ to -2 will give you a C-4 (seems the midi note is a C-2 and it wont go any lower) and should give you 1/4 notes. The math is slightly off so its not 100% on the beat. But warping will fix this.


So one could assume if you go up from Analog’s ‘osc’ parameter ‘octave’ to 1 or 2 one would get 1/32 notes and 1/64 notes. It does not work that way my guess is because it is not a drum its a waveform that starts to produce a continual note at that point so our ears can not differentiate between the separate transients at that speed.


So in the pack I have released with this tutorial I have bounced the C-2 (1/4 note) MIDI rhythm in to audio and warped it. I have also put the warp mode onto re-pitch (which will mess with the pitch of each pop as they are all different lengths) and created a very cool sounding rhythm. So next time your writing minimal tech keep this in mind for a rhythmic melody or something!


Just another quick note aimed more at Ableton use. If you don’t know how to print MIDI tracks to audio this is how to do it.





So on your channels you have drop boxes above and below the monitoring (In – Auto – Off) section. The top box is where you are taking your audio or MIDI from. In this case on the audio track I have set it to accept input from the ‘MIDI’ channel. The bottom box is where your sending your output to (audio or MIDI). In this case it is set to “Master” which will just send it to the master bus, which then travels out the main output. Once you have set your input and output it is as simple as arming record on that channel and on the transport bar and pressing play and waiting for it to record!


I hope you enjoyed this and here is at least an interesting way to make your own electronic bongo clicking and popping sound!


Download the live pack here: Mr. Bill – Sound theory Project


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Cheers,
Bill.