Is G#4 a native designation (meaning using MODX's own MIDI note numbering) - or using say a DAW's designation which may not be using the Yamaha system? I think you mean G#5 because this is a note range break for the top keys.

In the 1-Part Performances, a "cheat" is made to G#5 and above where only one velocity layer is used. They picked the "ff" (meat fisted) waveform for all of these notes. So if you're playing a delicate note below G#5 then delicately press a piano key at or above G#5 - the sample playback will be an aggressive one (always).

You can swap out the G#5-G8 range element with a less aggressive sample to try to optimize for your usage. Still, it's a compromise.

Do your test again and play G5 at fff so the most aggressive sample is played (highest velocity layer) for G5. Then play G#5. This should blend better. I say this only to help understanding - not that this "fixes" anything.

There are some options on how to fix. You may try dialing in an FEG to "dull out" those G#-G8 notes at lower velocities and get brighter at higher velocities. Instead of replacing the waveform altogether.

Hi guys, I bought a MODX7 a year ago and since the first day, I've noticed that the G#4 have a strange behaviour on the sound, that is very diferent than G4 and A4, this note just not sustain itself. Just checked on a MODX8 and a MODX6 from a friend and they have the same "issue"
Tryied on CFX Concert, CFX Stage, CFX PopStudioGrand and others performances with the CFX piano. For S700, S6 and other, it's ok
Is that a waveform issue?

Yamaha uses the convention where middle "C" is C3
So at G#5 you will notice a difference in the sound on the acoustic piano sounds ... it is around this point on a grand piano where the felt dampers are no longer available to muffle the strings vibration when the sustain pedal is released. They have no dampers__ "where" on an acoustic piano the undampered strings begin varies according to manufacturer and model.

This notes will sound different -- next time you are at an acoustic piano, check it out!

Why have both replies ignored leonardo's comment about A4?

Whilst you're both happy to immediately presume he's off by an octave?

It is obvious he meant to say A5, the note directly above G#4, is sounding normal, only one note is odd, not a range change.

I started by playing the indicated note with headphones and didn't notice an issue. Then made a leap. I'll let the OP chime in if I'm off center or not. Which would be fine because there may be a high frequency problem that escapes my ability to hear it. In which case I can take out a spectrum analyzer and see what it says.

So no, I didn't ignore it -- I just didn't hear anything with my somewhat limited audio capture "devices".