Dip refers to the distance the key travels downward.  So from the very top of the keystroke to the felt cushion at the bottom, the dip is the distance between the two.  Why talk about dip?  All pianos should have the same distance right? You would think that this is standardized but it’s not.  And believe it or not, 1 millimetre makes a HUGE difference in dip.  OK so there are some basic guidelines that piano makers follow.  Historically 3/8 of an inch was the standard.  This is just shy of 10 millimetres ~ 9.55 to be exact.  Personally i tend to lean towards just a hair past 10.  Bosendorfer publishes 10.2.  Yamaha and Kawai are in the vicinity of about 10.0 to 10.5.  I find that ‘shallow’ pianos – ones with under 9.5mm and ‘deep’ pianos – more than 11mm are ones that stand out.  And what happens if this is adjusted too deep or shallow?  Well, too deep and the keystroke feels a bit like an army tank.  Quite often i’ve heard it said that the piano feels ‘clunky’ or heavy.  This stands to reason because of the amount of travel your fingers are doing.  It requires a lot of effort to play a deep keyboard.  Too shallow and you may experience lack of power or a feeling that you’re hitting a wall.  Because the benchmark is closer to 10 these days, a 9.5 or shorter dip results in feeling somehow confined. 

So better than spinach or artichoke dip, a good key dip results in tasty playing.