Be picky about tuning! Don't avoid playing octaves or chords because they don't sound right. It's normal to have to tune your harp. This tuning check is the first step to getting your harps in tune.
Check your harp's tuning often - it only takes a few moments. Don't be afraid of what you might find.... Then go ahead and tune your harp!
Playing all the octave-splits on a harmonica is a fast way to pinpoint tuning problems.
Here, I play octaves throughout the harp to hear whether the two notes are in tune or not. The harp I play in the video is far from being in tune. You can tell by my facial expression the first few times I hit a "beating" octave. This exercise is mostly ear-training.
Warning! If you get proficient in this technique, you may begin to become afflicted with tuning-obsession-syndrome and get the feeling that most out-of-the-box harps are out of tune! In extreme cases, keen-eared victims raise an eyebrow when listening to over half of the recordings of blues greats such as Sonny Boy Williamson, James Cotton and Walter Horton!
Tuning check instructions:
I play the 1-4, 2-5, 3-6, 4-7, 5-8, 6-9 and 7-10 octave splits on the blow side.
Then, I play the 1-4, 2-5 (seventh chord, not an octave. so expect beating to be difficult to hear), 3-7, 4-8, 5-9, 6-10 splits on the draw side.
Then I play the 2-3 blow and the 4-5 blow. I play the 1234 draw chord and listen for dissonance.