I have an old Yamaha G7 of which I'm not happy with the sustain in the treble area. The third G above middle C in particular has very short sustain. In fact none at all when unison is dead on. This piano has had a Damp Chaser dehumidifier installed and plugged in 24/7 since I acquired it two years ago. We live in the tropics where RH is mostly above 80% year round and never goes below 70%.
Two days ago I unplugged the Damp Chaser because we needed to do some house maintenance. Now, I noticed increased sustain in general. The high G in particular has sustain now.
Am i imagining things?