All the comments above are good. Diatonics are nice if you want a full sound in one key; chromatics allow for more freedom if you do wacky stuff with lots of accidentals or modulation (like "Somewhere Over the Rainbow").

George Orthey has been building the harps that have been consistently chosen by the International Autoharp competition winners in Winfield (from amongst Oscar Schmidt harps, OrtheyHarps, and occasionally some other makes). Many of the top performers like these harps, though some go with others (John McCutcheon has a custom Bob Taylor harp). But George Orthey has retired, so you might have to look for a used one if you want one of his. The OrtheyHarps come in chromatic and diatonic models as well.

You can (if you're handy) turn any chromatic into a diatonic) if you want, including stringing the double courses mentioned by one of the prior poster. You will need to get custom chord bars, or blank chord bars, and cut them yourself.

Diatonic harps can be tuned for perfect intervals, as opposed to the even-tempered intervals of the chromatic harps. This gives a slightly sweeter tone than the even-tempered tuning, but may be apparent in such places as your major third (386 cents versus 400 cents for the even-tempered third) when you play with someone else.

Custom harps are also an option, once you know what you want. I built myself a harp a while back, designed with my tastes in mind. It has 52 strings, with all courses doubled. It is basically a diatonic harp, but with a couple of extra notes (also diatonically tuned) added in for some extra chords outside of the C-F-G/G7 chords. In addition, one of its strangenesses is that it had two D notes (it's a C harp). One is the diatonic D note from a F minor chord (at 182 cents), while the other is the diatonic D note from a G major chord (at 204 cents). This harp is also a bit bigger than your standard harp.

Feel free to e-mail me at zuch@ix.netcom.com if you have more questions or need more information.

Happy harping!

Cheers,

-- Arne Langsetmo