[sdiy] MIDI2CV & Arpeggio question..

[Laurie Biddulph]

The General MIDI standard organized this musical chaos by decreeing that all 
GM -compliant patches must play an A440 pitch in response to a MIDI command 
that included the MIDI note number 69. All other MIDI note numbers were 
calibrated according to this standard so that the same note number would 
play the same note on any GM-compliant sound module, regardless of who 
manufactured it. Drum sounds were similarly standardized; with 48 MIDI note 
numbers standardized to correspond with 48 particular drum sounds.

I found this extract for the Octaves:-

  The MIDI (Musical Instrument Device Interface) standards unfortunately do 
not designate octaves. The standard merely designates that Middle C is note 
number 60. Thus, MIDI users have had to create their own designation systems 
using the MIDI numbering system. Understandably, the most logical octave 
designations were the existing designations superimposed over the MIDI 
numbering system. There are at least two accepted octave designation systems 
for the MIDI numbers. Part of the problem stems from the fact that the notes 
of the keyboard (or any other instrument) are no longer a limitation in the 
range of pitches available.
  One version of the MIDI system uses C3 to designate Middle C (MIDI note 
60, 261.626 Hz). That means that the octave designation for MIDI note "0" 
would be "-2" or notated as C-2.

  Another version of the MIDI system uses the lowest note available to the 
MIDI system (MIDI note 1, 8.176 Hz) to designate Octave "0" with the 
notation of C0. In this system, Middle C (MIDI note 60, 261.626 Hz) is 
octave 5 with the notation of C5.
I tend to use the last one (at the moment)

Best Regards

(Mr) Laurie Biddulph
Phone: +61 (0)2 4340 0938
Mobile: 0400 257 645

Elby Designs
ABN: 70 022 727 605
http://www.elby-designs.com

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----- Original Message ----- 
From: "Forbes, William ALGLSG-LXES" <william.forbes at schaeffler.com>
To: <madhun2001 at yahoo.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, March 03, 2009 7:15 PM
Subject: RE: [sdiy] MIDI2CV & Arpeggio question..


> 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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