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### Octave overlap in uTune?

Posted: Thu Feb 01, 2018 4:26 pm
I found the solution. See the last lines.

I wrote to you on the blog page but thought I'd take your advice there and write here as well...

I have a pentatonic octave scale that I like to use with midi from a standard keyboard. When playing the scale the point at which the next octave begins is doubled. In other words lets say the ROOT is note value 61 and the octave is note value 66 five key presses above the root. The NEXT note played on the keyboard which is a single semitone above the octave is reading 67 on the uTune display but is exactly the same voltage as the previous 66 value, so each octave has a one-note duplicate key before proceeding on through the scale. The same effect occurs traveling lower on the keyboard.

Here is another way to explain it...

C#3 = midi 61 (ROOT)
D3 = 62
D#3 = 63
E3 = 64
F3 = 65
F#3 = 66 (OCTAVE)
G3 = 67 (OCTAVE AGAIN) This is where the voltage output stays the same as the previous note so I get the same OCTAVE note on my VCO. Each subsequent note up the keyboard follows the scale map fine but are shifted down by one note value voltage.

This makes a nice symmetry for playing. Every other octave (two octaves up form the original root) is exactly the same on the keyboard but I am also using the uTune module with midi tuning software to my other midi to c/v modules so there is a tracking problem. They output the scale correctly and I get a progressive offset across the octaves.

Is there a parameter to edit which can smooth out this duplicate note overlap?

Also I notice this does not happen if I choose to use a scale with 12 tones or more. I haven't tried other variations of less than 12 notes yet, just 5 notes.

Here is a truncated description of the scale I am loading into uTune if anyone wishes to duplicate it...

NAME: 5 EDO, Sulendro 13113

(note count) N:006

01 : 1/1
02 : 9/8
03 : 4/3
04 : 3/2
05 : 16/9
R : 2/1

a very simple Javanese scale.

EDIT: I found the cause of my problem. I have too many entries in the table. I dropped out the 1/1 on the first entry and everything is fine. Learning as I go here.

Posted: Fri Feb 02, 2018 3:34 am
Happy you found the answer, for completeness I am including my answer I already sent you via mail:

Hi. The reason for this is the way you defined the scale. The unison 1/1 for note 1 is always implicit. So by defining it again you created this double note. Have a look at other scales, the initial 1/1 is always missing. This is how scales are defined in scala.

So your scale should be
Note count: 5 (it is pentatonic after all)

01: 9/8
02: 4/3
03: 3/2
04: 16/9
R: 2/1

Posted: Fri Feb 02, 2018 4:29 am
I can already see the next question coming from someone else:
But what if I want a scale without the 1/1 entry?
Well there are two solutions to this. One involves math, the other makes use of a feature unique to µTune.

The µTune solution
µTune can deactivate certain notes in a scale. (In the scale editor this is the small arrow next to the note number). If you want to deactivate the root, just deactivate the repeating interval (2/1).
If you try to play a deactivated note, µTune will pick the nearest active note and play that instead.
Deactivated notes will be saved with the scale, and scale files are still compatible with the scala format. By the time of writing however the deactivation is ignored by other systems.

The math solution
This has actually nothing to do with µTune, but applies to all Scala compatible devices.

First of all it is important to understand how a scale is constructed in scala. There is always some base note (1/1) and all other intervals are defined relative to this note. So the entry 9/8 means: 9/8 * 1/1.
As you can see, it is not only unnecessary to include the 1/1 entry, changing it would also be meaningless as it is just a reference for all other intervals.

The scale is repeated with a certain interval, which is the last entry of the scale. In µTune this entry is marked with R, the repeating interval. In this case it it 2/1, an octave. So if all notes of the scale are used, the next notes will be 2/1*1/1, 2/1*9/8, and so on.

So if you want a scale, that does not include its root you must chose a new root. In the example above this would be 9/8. Now you divide all notes by 9/8 so the relations by all intervals are maintained.

00: (9/8) / (9/8) = 1/1
01: (4/3) / (9/8) = 32/27
02: (3/2) / (9/8) = 4/3
03: (16/9) / (9/8) = 128 / 81

Our new scale thus becomes:

01: 32/27
02: 4/3
03: 128/81
R: 2/1

Hoped this was more informative than confusing.

Posted: Fri Feb 02, 2018 11:09 am
Thanks Tobias.

The extra explanation is helpful. I was initially confused due to having used another software which includes the 1/1 in the ratio strings. LMSO is one such program I use quite a bit. It's no longer available it seems but it is pretty good at playing all the various tuning file formats and exceptional at creating non-octave scale tunings.

Speaking of which...

I have been using LMSO for quite a few years and in conjunction with my DAW (Cubase) and the MOTM 650 MIDI to CV/GATE module to do polyphonic alternate tuning work. I was excited about µTune as a way to add something to the setup. I have been trying to duplicate some octave scales so that both are playing the same thing as a simple experiment and exercise in understanding the tools better. I notice I have to offset one or the other a bit with a semitone voltage in order to get everything to work out. µTune has the perfect ability to do this with the keyboard mapping so thanks for that. I also have to use a standards module to finish off the offset.

I am using a Synthesizers.com Q123 module which has octave and semitone selection as well as inverted mode. I did check often to make certain the vco's were all tuned initially to the same pitch/voltage before applying any exponential control voltages from the midi to cv modules and that an appropriate warm up settling time had occurred.

With the example scale from this thread (correctly applied this time), I have the keyboard mapping set for G6 and 6 volts for the middle note. My scale anchor middle note from the other software is A3. I also am applying a -0.25 volt at the standards module. I worked at this for a few hours yesterday to try almost every combination I could think of to bring the tracking in line between the two patch paths. I think there are other combinations but I wasn't successful in figuring out one which had the same "middle note" setting for both. I also could never avoid the offset voltage from the standards module.

Despite the extra troubleshooting puzzle the project was successful enough to render two entirely different setups working in tandem to produce a pair of identical scales played from one keyboard source in real time. Yay! The result was a magical way to play the modular whereby the selection of notes from the keyboard through MIDI were interpreted slightly different giving a robust choice of vco's to each note. Each key press was selecting a different pair of vco timbre's due to the way the modules and MIDI train were set up. I am really excited about what is in store for the future with the expansion module.

I did notice the keyboard mapping voltage values are set for 1/12th volt per division. Exactly what is useful for 12tET. This is a very good thing in general for use with a standard keyboard and yet I am still a little confused as to why I couldn't just set the voltage at the module in this mapping parameter and not have to use the standards module as a final offset. Some of the notes in the simple 5 note scale were still quite a bit off but most were correct. I was thinking it was more due to the scale I programmed. The intervals are equidistant except for a couple so if I had everything right except the "middle note" or root then the scale might partially line up.
A bit confusing to say the least, and it's entirely possible I still have something a bit whacked out. It's fun regardless.

Sorry for the long post but it is tough to explain the experimental project in a few words clearly. Thanks again for the great multitool and all your efforts so far. I look forward to seeing the expansion module soon.

-David

Posted: Fri Feb 02, 2018 1:37 pm
Not certain if I understand you setup completely. Mostly because I don't know most of the gear involved.

But in generally I recommend to set the keyboard mapping middle note to a value that is more or less the middle of the ranges of notes you intend to play.
The middle note will also map the scale root to a certain keyboard key, so this should be the same in other gear (motm). Otherwise you will play two scales with different root notes.

The actual tuning should be performed with a defined note played on both setups (G6 for example) until both setups have the same pitch.

following this both setups should track well - provided of course that the other CV interface has the same (or better) precision as µTune.

Hope this helps a bit