>1) Why don't I hear about Equal vs. Just tuning on other instruments
that >play both single notes and chords? You never hear guitar or piano
players >discussing this. Why only harp?
It is a topic that comes up several times a year on a mountain dulcimer list
that I'm on. It's a (normally diatonically) fretted instrument that most
people play in linear fashion along the treble (melody) string, and you can
create chords with the other strings. Normally it's a 3 string instrument.
They are zithers (fret board is over the sound board). Strum sticks are
basically mountain dulcimers with necks. I think any harp player could learn
to play one of those fairly quickly.
In many ways it's like a harmonica; low notes on the left, high notes on the
right, you must bend notes to get the ones that aren't part of the diatonic
scale. Chord inversions, intervals (partial chords (sic)), and octaves are
common techniques. So like a harmonica, they want the melody notes to have
an intonation that people expect, but when they chord they want the chords
to be sweet (dulcimer=sweet sound). It's a folk instrument that you can
build for yourself fairly cheaply, I've built a few. Since that's the case,
setting up one for a just tuning to play in D, another G, another A, etc. is
actually feasible. I played it first, mostly old-time and fiddle tunes, and
found that I could play anything on my harp that I could play on it when I
started playing the harp.
But these are modern times and most people have them fretted for ET so they
can jam with the guitars, banjos, and fiddles and sound "right". A solo
performer might well want a just tuning of some sort, but it doesn't seem
too common. But the harp is not as unique as it might seem. Mine are ET by
the way, but then I play Lee Oskar harps. :0) And I spend more time playing
my harp than my dulcimer.