Tuning (MBFM)

[eptheca]

I would like to try out different tuning on my MIDIbox synths.

 

I have found the mbfm_frq_table.inc, but I am not sure how the values work.

It's a little bit different from the SID

 

Can some one please explain to me which values to change, and how to calculate them

I assume it's not as simple as just changing the Hz. values

 

Best regards

Halvor

[TK.]

The algorithm to calculate the tables is described in this perl script: http://svnmios.midibox.org/filedetails.php?repname=svn.mios&path=%2Ftrunk%2Fapps%2Fsynthesizers%2Fmidibox_fm_v1%2Futils%2Ffrqtab.pl

 

Best Regards, Thorsten.

[eptheca]

Thank you TK,

 

I have looked at it, but still not sure how I would do it.

The tuning I want to use is not a tempered scale, where all the semitones are evenly spread out.

I have all the Hz frequencies for each semitone

Is it possible to just calculate each value manually, and change them?

 

For example, in my scale C2 is 128.000 Hz

Which values in the code would need to be changed, and how would I calculate them from the Hz value

 

	db	0xac, 0x10	;    130.813 Hz (4:0ac  C-2)
	db	0xb6, 0x10	;    138.591 Hz (4:0b6  C#2)
	db	0xc1, 0x10	;    146.832 Hz (4:0c1  D-2)
	db	0xcd, 0x10	;    155.564 Hz (4:0cd  D#2)
	db	0xd9, 0x10	;    164.814 Hz (4:0d9  E-2)
	db	0xe6, 0x10	;    174.614 Hz (4:0e6  F-2)
	db	0xf3, 0x10	;    184.997 Hz (4:0f3  F#2)
	db	0x02, 0x11	;    195.998 Hz (4:102  G-2)
	db	0x11, 0x11	;    207.652 Hz (4:111  G#2)
	db	0x22, 0x11	;    220.000 Hz (4:122  A-2)
	db	0x33, 0x11	;    233.082 Hz (4:133  A#2)
	db	0x45, 0x11	;    246.942 Hz (4:145  H-2)
	db	0x58, 0x11	;    261.626 Hz (4:158  C-3)
	db	0x6d, 0x11	;    277.183 Hz (4:16d  C#3)
	db	0x83, 0x11	;    293.665 Hz (4:183  D-3)
	db	0x9a, 0x11	;    311.127 Hz (4:19a  D#3)
	db	0xb2, 0x11	;    329.628 Hz (4:1b2  E-3)
	db	0xcc, 0x11	;    349.228 Hz (4:1cc  F-3)
	db	0xe7, 0x11	;    369.995 Hz (4:1e7  F#3)
	db	0x04, 0x12	;    391.996 Hz (4:204  G-3)
	db	0x23, 0x12	;    415.305 Hz (4:223  G#3)
	db	0x44, 0x12	;    440.000 Hz (4:244  A-3)
	db	0x66, 0x12	;    466.164 Hz (4:266  A#3)

 

 

Edited January 5, 2015 by eptheca