[sdiy] MIDI2CV & Arpeggio question..

[Tom Wiltshire]

Laurie's dead right - there is no standard for octave numbering, only  
note numbering. Stick with middle C = note 60, Concert A = note 69  
and you'll be fine.

T.


On 3 Mar 2009, at 08:41, Laurie Biddulph wrote:

> 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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