I recently discovered that the Solton (Ketron) SD1 uses a chord recognition method (in full keyboard 'pianist' mode) which differs greatly to Technics KN arranger keyboards and possibly Yamaha too.

Checkout the below example for the very 'basic' D minor 7th chord (3rd inversion):

On the SD1, when you play (in 'pianist' mode) a simple Dm7 chord voicing (C-D-F-A) with your left hand, and then play the 'single' notes with your right hand, in slow succession: D-E-F-G-A-B-C (dorian chord scale), you will notice that the chord recognition changes to C13 when you play the notes E or G (lead/melody notes). I don't like this because the harmony and associated auto-accompaniment bass line will jump to a C13 which is not in keeping with the required "D minor" chord tonality of the intended chord. I realize that the SD1 also includes a mode called AUTO mode. In AUTO mode, any time you press a 3 note (or more) recognized chord, the keyboard does'n't accept new chords as long as you play 1 or 2 notes maximum as lead or
improvisation in the right hand. Unfortunately this only partially solves the problem of the unexpected harmony change to C13, as it allows you to only play a 1 or 2 notes maxiumum in the right hand without changing the original chord recognition harmony. Unfortunately, this same chord recognition problem also occurs when playing (on the SD1) most all other basic chords as well (G7 etc).

On the other hand, the Technics KN keyboards allow you to play right hand lead-melody and/or improvisation (without the 2 note (auto mode) limitation the SD1 has), and the KN keyboards also allow you to play ALL notes of the associated chord scale without the chord recognition suddenly jumping to a different chord root or tonality (major, minor, dominant) as the SD1 does.

The SD1 also has a mode called STANDARD mode. In STANDARD mode, anytime you press the Sustain Pedal, you " freeze " the current tonality and you can perform on the keyboard as a regular Piano. I personally don't think this is practical as it potentially conflicts with normal sustain pedal playing techniques used for standard piano playing.

I would have much prefered that Solton (Ketron) implemented the chord recognition design used by Technics & (Yamaha?).

I am now VERY interested in finding out how the Yamaha PSR9000 and 9000pro recognize the below D minor 7th chord (in full keyboard mode) when the right hand (concurrently) plays the associated chord scale notes: D-E-F-G-A-B-C. Yamaha arranger keyboard owners, PLEASE test and report back your findings here. Thanks in advance for all input and feedback on this subject. - Scott

Dm7: Chord voicing (C-D-F-A) PIANIST mode:

left hand: right hand note: SD1 Recognition:
(C-D-F-A) D Dm7
(C-D-F-A) E C13
(C-D-F-A) F Dm7
(C-D-F-A) G C13
(C-D-F-A) A Dm7
(C-D-F-A) B Dm67
(C-D-F-A) C Dm7

left hand: right hand note: Technics KN Recognition:
(C-D-F-A) D Dm7
(C-D-F-A) E Dm9
(C-D-F-A) F Dm7
(C-D-F-A) G Dm11
(C-D-F-A) A Dm7
(C-D-F-A) B Dm67
(C-D-F-A) C Dm7