I stumbled upon an unusual behavior of all of my currently installed Synchron Pianos (Yamaha CFX, Steinway D-274 and Bösendorfer Imperial) where the sympathetic resonances seem to ignore the use of the sostenuto pedal.

An example on how to recreate my issue would be by cranking up the sympathetic resonance volume of a synchron piano, playing C2, holding down the sostenuto pedal, releasing C2 and then playing C3 (preferably staccato). Then compare that to simply holding C2 down and playing C3 (preferably the same way it was played previously).

This is also noticeable when playing high velocity notes, holding down the sostenuto pedal, then releasing the keys while still holding down the pedal. There is suddenly a drop in volume due to (what I assume are) the sympathetic resonances stopping while the keys keep slowly fading out.

Now I'm curious if this is only on my end, or maybe a bug or design decision?

Thank you in advance,

J T