Rex Gehlbach sent us this great tip:

I just discovered that my RP155 has a great chromatic tuner built in. Just hold both foot switches down until it says TU. The default is A=440 but the first knob will adjust it to A=441 or 442 or whatever you need. I found it to be very stable and easier to tune with than the Sabine tuner I have used for years. I’m going to post this over at harptalk in case there are other knuckle heads like me who don’t read the owner’s manuals when they buy something! I was happy with it already and now I get this added bonus. Cool.

Thanks Rex! We especially like that you can adjust the reference to A=whatever you like, given that so many harp players like to tune the harp to A=443 or A=447 os they can play harder without going flat.