When used acoustically it's been my experience the needle and/or indicator light wobble back and forth between slightly flat and slightly sharp. Alot of times I'd frustratd and just get it 'in the ballpark'. Especially my mandolin. When doing a session once the engineer's assistant handed me a little clip-on mic they'd gotten from Musician's Friend for $5.oo. It was like the parting of the red sea. It's got an 'alligator clip' w/pads and a 1/4" 6ft cord attached. Attach it to your bridge, tune, then take it off. What I've also done is this: take any mic w/a 1/4" cord and plug it into the input jack on the tuner. Use the mic close to your instrument. Not nearly as much 'wobble'. A little off topic, but as I play(not very well) dulcimer, also I thought you'd benefit from these suggestions. I purchased two of the clip-on mics in w/an order for some strings, stands, etc.