Since you already play the violin and mandolin y ear, you should be able to master the erhu to some extent.
Holding the instrument properly will be your first challenge, since it is held differently from a western violin/ fiddle. Turns out the bow hairs run under the strings:
The player usually sits, resting the erhu on one leg, pulling the horse hair bow horizontally between the two vertical strings. The bow is never played outside the strings.
(Quote from the crossound link below.)
Some insight into the natural minor harmonic scales appropriate for this kind of instrument would help.
Try this G minor scale over 2 octaves:
G A. Bflat, C, D, Eflat, Gflat, G’, A’, Bflat’, D’, D’, Eflat’, Gflat’, G”
I find the tonal centers from D running up to Bflat’ to be a kind of Japanese Noh scale.
If you live in a place with a larger population, you might be able to find someone who already knows how to play–something– on the instrument who can give you some insight. Try posting an ‘instructor wanted ad’ on the Craigslist for your area, or something of that nature.
Try working out some old simple fiddle standards– slower ones– on this, say “The Water is Wide,” or “Will the circle be unbroken?” just to see how it works.
You may find that the instrument has its’ own voice, its’ own soul, and will tell you what it wants to play…so keep your ears open for that eventuality.
At some point you can make up some of your own material: write an A-part melody, play that twice, and a B-part contrasting melody and play that twice. (That’s the structure of about 90% of old time fiddle numbers..)
Since you have two instruments already, you can download the Audacity software and record some of your own backing tracks to play against:
You might need a mixer and a good mike for this.
Alternately, look into one of the miniature digital recorders that are out now, such as the Boss BR or Roland Edirol units.
However, since you already have a computer, you might just as well buy a good mike.
And if possible send me an MP3 when you get something down.
Maybe we can jam someday when I get the hang of the kora that I’m going to build…
And while we’re going on about unusual stringed instruments, have a look–and a listen– at The Lyre Of Ur, here: