[sdiy] MIDI2CV & Arpeggio question..

[Forbes, William ALGLSG-LXES]

Hi,

I'm always confused by the octave numbering.
I've always assumed that Middle C is MIDI note 60 = 261.63Hz and A above
middle C is 440.00Hz

This would tend to make MIDI note number 0 five octave lower than middle
C at 8.18Hz
I've always assumed that this octave (MIDI notes 0 to 11) was octave 0
and thus Middle C was C5

Is my understanding correct?

What is the correct numbering?

I also assume the numbering goes

C0-B0 then C1-B1 etc.

Cheers
Bill. 

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Tim Ressel
Sent: 02 March 2009 17:49
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] MIDI2CV & Arpeggio question..

Jean-Pierre,

I like to use the notation (pun intended) of middle C = C4 = 261.6 Hz.
This makes C0 = 16.35 Hz and C10 = 16742.4 Hz. Then I simply make the
number be the volts: 4 volts = C4. This yields 0-10V = 16-16000 hz.

This arrangement has an added math advantage when working with a
processor: the conversion from volts to frequency is (2^Volts_in) *
F_lowest. In other words, if you want to sample a CV and produce the
corresponding frequency, raise 2 to the power of the CV voltage and
multiply by the frequency you want 0 volts to be. 

--TimR

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