It's hard to say exactly which are quietest and loudest because the sounds are different pitches and occur at different times. I agree with Jarosujo about the Kawai wood actions (AWA Pro 1 and 2, RM3, GF) that they are on the quieter side and also they have a lower pitch. Kind of a "whump" sound that I personally find less obtrusive than many other action sounds.
On the other side of the scale in my experience are the Avantgrands. I don't know how they compare in terms of decibels, but they sort of make a bunch of different sounds (because the action is so much more complex) as the key goes down. Each individual sound isn't too loud, but overall I find them quite distracting to play. I'd probably opt for closed headphones if I had an AvantGrand.
Most of the other actions are in between those two extremes. Roland (PHAIII) is quiet until it bottoms out, but I find the bottom out noise sharper and more distracting than Kawai. Personally I'd put the Yamaha GH/GHE/GH3 actions between the Roland and the Kawai.
The physical build of the piano and what stand it rests on matters as well, so sometimes we can't even class noise by action. The MP8/MP8II/MP10 line is particularly heavy for a stage piano, which I think contributes to its low action noise. It may be that the physical lightweightness of the Casio you refer to is a contributing factor, as well as the stand on which the original poster had it.
Of course, none of them are a real problem when playing with speakers at acoustic-like volumes. But with headphones on or playing at low volume, action sounds do matter. By the way, we had some threads earlier this year in which people were complaining about the Kawai action sounds. The problem was that the lower pitch traverses walls and floors more easily than higher pitches and can bother others around you. I guess there's no perfect action in this respect.
Last edited by gvfarns; 12/06/12 03:09 AM.
