sort of undertones when playing Rhodes in range C5-C6

[fran]

Hi,

My Rhodes stage mark II produces sort of undertones when playing 2 or more voices simultaneously in the range of C5-C6.
Example: when I play C5 with E5, I hear a D flat (Db2). Next I play D5 with F#5, I hear a Eb2 and so on.
I have the same result but less annoying when playing triads like C E G or an inversion in the range of C5-C6, I'll hear the fundamental of that chord in the range of C2-C3.
The Rhodes has been maintenanced an is in good shape. So what might be the problem? Thanks!

Here you can listen to the problem:
https://youtu.be/Ntpjip9Cfiw

[Jenzz]

Hi :-)

I can't hear any undertones, just the normal intermodulation that you get when playing certain intervals (which is normal on a Rhodes).

Is this a miked sound from an amp?


Jenzz

[gacki]

I somewhat hear it in the higher examples; it's pretty much the same with a grand piano.

https://en.wikipedia.org/wiki/Combination_tone

Interestingly the German wikipedia entry

https://de.wikipedia.org/wiki/Kombinationston

gives a similar example: C together with E (in the same octave) results in a combination tone two octaves below but a semitone too high in equally tempered tuning.

Pretty much the only thing one can do about this is using an effect that masks this phenomenom; a chorus might work fine here.