8/2/09 4:01 PMReaktor For You Community - Pitch & Frequency - Part 1

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reaktorforyou

Reaktor For You Community

Native Instruments Reaktor Community

Pitch & Frequency - Part 1

reaktorforyou March 1st, 18:05

FREQUENCY AND PITCH :: PART 1

In the very first tutorial I'd like to discuss Frequency and Pitch and their role in Reaktor. This tutorial is certainly

not for beginners, but not for advanced users either. I advice you to read manual before you start reading this

tutorial.

Pitch & Frequency, the difference

Frequency in sense of physics is number of repeating periods per time (as usual in computer world per

second) and pitch is a perceived fundamental frequency of the sound. In Reaktor Sample Rate Clock ticks

every period of frequency, that means every 1 / Sample Rate (usual 44100 Hz).

Actually pitch is itself a frequency, but pitch is used more like musical term, while frequency is more like

mathematical and physical. For example, one can say "The frequency of oscillator is 440 Hz per second" while

other would say "That's an A note above middle C note". Both are right, but first speaker is talking in terms of

physics, while second speaker is talking about musical note. By meaning 440 Hz you mean exactly 440 Hz,

while pitch is more flexible. Here you can find a more detailed description of difference between pitch &

frequency:

http://emusician.com/tutorials/emusic_pitch_vs_frequency/

(http://emusician.com/tutorials/emusic_pitch_vs_frequency/)

Standardized pitch is A4 equal to 440 Hz.

Connection between Pitch & Frequency

There is straight connection between pitch & frequency. When frequency rises, pitch rises as well, when it falls,

pitch falls as well.

Pitch can be converted to frequency using next formula:

- where p is current pitch

Frequency can be converted to pitch using next formula:

8/2/09 4:01 PMReaktor For You Community - Pitch & Frequency - Part 1

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- where f is current frequency

If you want to look at pitch & frequency tables you should look at these links:

peabody.sapp.org/class/st2/lab/notehz/ (http://peabody.sapp.org/class/st2/lab/notehz/)

www.cis.hut.fi/Studies/T-61.140/Vinkit/hertz.html (http://www.cis.hut.fi/Studies/T-61.140/Vinkit/hertz.html)

Converting pitch to frequency in Reaktor

Okay, after digging a bit into theory, let's finally look inside Reaktor. We will build two core cells implementing

above formulas and will make a short research of how it behaves.

I'm sure you have read manual before and you know how to work in Reaktor, at least how to make new Core

Cell, how to insert, move, delete wires and modules.

That's how both Core Cells look like in Reaktor:

(http://pics.livejournal.com/reaktorforyou/pic/000031q0/)

Comments:

1) Why I used Event Core Cells instead of Audio Core Cells? My advice is to avoid audio operation when we

don't need them. In our case we don't operate with audio and we don't need to use audio core cells.

2) Don't forget to switch exp and log modules to 32 bit precision to get more precise values (but don't forget it

also takes more CPU load, so use it when you really need it).

3) Avoid too large and too small values for pitch input. Too small values of pitch will give de-normal values of

frequency and more CPU load (maximum allowed value in Reaktor is 1e+38 and minimum is -1e+38: setting

up higher or lower constants in core will crash Reaktor).

Task:

Try to connect knob to input of core cells and meter to output. Look at values and connection between pitch

and frequency.

Next tutorial will be about how and what for do we use low frequency and pitch.

8/2/09 4:01 PMReaktor For You Community - Pitch & Frequency - Part 1

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