Koen, thanks for your posting….. The attack and release times of the P10 are very definately ‘nominal’ (!) They vary hugely depending on the transient nature of the the signal. I’m sending you the circuit diagrams so that you can see the compound attack and release components….. the most important one being C26 (100nF) which sets the attack time depending on the slope of the transient detected, the setting of the attack control and the residual charge in the main capacitor underneath it.
When I designed the P10 I had intended to be accurate about attacks and releases, but in practice in the studio the variation is huge, and the right way is to listen!
Of course, piano is notoriously difficult to compress successfully, and again it depends on the touch of the player, and the type of music.
I will send the circuit diagrams by regular email.