Hi Bob,
harmonica tuning is a complicated business, some would say, a can of worms. It’s not an exact science, the slightest change in air pressure will give you a different result. Personally I use A=442HZ with light air pressure as my starting point, I try to measure at the highest possible pitch of the reed, as this is the only fixed point of reference.
The models you list don’t all share the same fine tuning. Hohner uses 3 basic set-ups:
Golden Melody = equal temperament 12TET
Rocket, Marine Band 1896, MB Deluxe, Sp.20 = Hohner Classic tuning
MB Crossover, MS Series = compromise between 12TET & Hohner Classic
7 limit JI is how harmonicas used to be tuned in the (fairly distant) past. Here all major thirds are -14ct and the 7th in the draw chord (5- & 9-draw) is tuned -30ct. That’s extremely flat to my ear and means this tuning is only really suitable for old timey solo performance. The chords sound great though.
I set the tuning specs for the Crossover myself, I’ve tuned my harps that way for a long time now because it still gives you decent sounding chords, but the individual notes are close enough to equal temperament that they sound OK together with other instruments or when using positions to play in different keys. Here are tuning charts for all 4 options ( Blasplatte = blow plate, Ziehplatte = draw plate), hope that helps.
