Bennevis: Yes, that's stretch tuning. Just a tidbit of info, but I once asked a piano tuner (actually - a piano engineer
) whether he would stretch tune the piano I had hired him to tune, and he said "all pianos are stretched", and explained the issue regarding the inharmonicity
of piano strings. It's just standard practise to tune pianos that way.
I think it's common now for DPs to be stretch tuned as well, however there may be an option for equal temperament, so that it sounds in tune when layered with other instruments. (my Casio PX-330 has this option) I.e - when layered, it may be more important for the piano to not beat against the other instruments, than it is for the piano to sound optimum by itself.
My V-Piano's default tuning setting is equal temperament, and unstretched. It has seven different user-selectable unequal temperaments (including the very weird 'Arabic' with microtones); and two different degrees of stretch tuning ('gentle' and 'deep') as well as 'user' are offered.....I still haven't figured out how to access the 'user' one, which I suppose allows any degree of stretch you want up to +100 on the dial
. But I've long ago set the tuning to 'deep' stretch (it just sounds nicer); and I prefer equal temperament for most of what I play, as the music modulates frequently to remote keys, for which the V will simply sound badly out of tune if I have unequal temperament dialled in. But when playing Baroque music (Bach, Handel and Scarlatti), I often experiment with some of the unequal temperaments - a perfectly tuned third is a sound of great beauty
. You also have to set the temperament key to the key of the music when you do that, otherwise everything
can sound horrible....
So, I suspect most (all?) DPs in their factory default setting have their tuning unstretched, and in equal temperament, but it would be interesting to see what sort of tuning options (other than transposition, which I suppose is universal for electronic instruments) other posters' DPs have, and what setting they prefer to use.