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Viewing topic "Chord recognition in XS-type arpeggios"

Posted on: March 31, 2018 @ 01:04 PM
Total Posts:  52
Joined  07-27-2017
status: Experienced

Does anyone know if the algorithm used for chord recognition in the XS-type arpeggios is publically available?

I have worked out this much ...

Major, minor, dimished and augmented triads are recognised as such in root position.

Major and minor triads can be inverted and are recognised correctly.

Dominant 7th chords are recognised correctly if all notes are present in root position and in all inversions.

Minor tth chords are recognised correctly in root position, and 2nd and 3rd inversions. In 1st inversion they’re recognised as 6th chords on the lowest note (i.e., the minor 3rd of the 7th chord).

“Straight” (i.e., not altered) 9th chords are recognised correctly in root position if all notes are played; they’re also recognised if the root and/or fifth are omitted - e.g., E, Bb, and D is recognised as a C9.

Flattened or sharpened 9th chords need the fifth and root to be played to be recognised correctly.

11th and 13th chords need the root to be played.

Recognition of 9th, 11th, and 13th chords in inversion - too difficult to work out (my ear isn’t fantastic) - is a bit hit-and-miss. Mostly miss. Plus, of course, these chords can often be interpreted many ways anyway.

I’d love to see a flowchart that shows how the MOXF works it out! It’s all very well saying the arps are “chord intelligent” but if you don’t know the rules on chord voicing it’s very difficult to second-guess what the recognition tool is going to do. It matters quite a lot for basslines!


  [ Ignore ]  

Posted on: March 31, 2018 @ 02:51 PM
Total Posts:  10623
Joined  09-16-2010
status: Legend

As far as I know, Yamaha has never revealed details of the “intelligent chord recognition” of XS-type Arps. A typical response when the topic has come up previously can be found in this thread:

It seems you’ve sussed out quite a bit - thanks for posting the information. Is what you’ve determined true of all XS-type Arps?

  [ Ignore ]  

Posted on: March 31, 2018 @ 10:44 PM
Total Posts:  52
Joined  07-27-2017
status: Experienced

I guessed it wouldn’t be publically available but thought it worth asking. I imagine it is buried somewhere in a Japanese-language Yamaha patent application but I’m not desperate enough to go delving into their patents.

I can do some more experiments to try to reverse engineer it, perhaps by recording the arps to the sequencer and looking at the notes rather than relying on my ear.

Does it work with all XS arps? I’m not sure - there are rather a lot of them :-) I just did my experiments with an XS-type bass arp (can’t remember which one now). It’s a question I hadn’t thought of - I presumed, possibly incorrectly, that the algorithm would be the same for all arps. But maybe not.

  [ Ignore ]