[Harp-L] Marine Band Crossover Tuning



Several people have asked about the fine tuning used in the MB Crossover. When I was developing this model with Hohner in Trossingen I suggested using the fine tuning that I've used on my own harps for many years, as it allows you to play in tune with other instruments in different positions but still gives most chords without interference beats. The MB Deluxe on the other hand uses the same tuning as the Marine Band Classic and Special 20, also a compromise tuning, but closer to Just Intonation, whereas the Crossover is closer to tempered tuning.

For this model I fine tuned master reed plates three times with 2 week-long rest periods in between. The tuning values of the master plates were then read off on the tuning table and test instruments were tuned to those values. Then I checked and corrected these to try to eliminate systemic errors. The production models I've subsequently tested were good enough for me out of the box and were about as close to my specs as you can reasonably expect from industrial production (no liability for any inaccuracies!).

These note values are intended to sound in tune with other instruments tuned to A=440Hz at "normal" playing volume and are measured on the comb but without covers (with the covers on they're a little lower). They represent ideal values and will still sound OK within a margin of error of 2-3 cents (it's very hard to tune to within 1 cent accuracy). I always tune with minimum air pressure as the only fixed point is the highest possible note a free reed can produce. Everything lower than that is a variable which is subject to the individual intonation of the player and will lead to different results from different people. To achieve this I leave a gap between my upper lip and the harp when playing the note while tuning, in order to reduce pressure differential to a minimum. It's also more important that the harp sounds good than that the note values are exactly as stated below, as tuning harmonicas is anything but an exact science. I proceded as follows:

0=443Hz w. minimal air pressure, all deviations are in cents, 1Hz = approx. 4 cents on most tuners

Blow reed plate:
Root notes (1, 4, 7 & 10) tuned to 0
Thirds (2, 5 & 8) minus 5 cents
Fifths (3, 6 & 9) + 1 cent

Draw reed plate:
1-draw is very difficult to measure accurately. With absolutely minimal air pressure maybe +8 cents, more in low keys. Like that it will sound right with normal air pressure. It's essential that it sounds good when played together with 2-draw and as an octave interval with 4-draw.
2-draw + 4-6 cents depending on the key, at normal air pressure it should sound at the same pitch as 3-blow
3- & 7-draw tuned to 0
4- & 8-draw 1 cent higher than 2-draw (i.e. + 5-7 cents)
5- & 9-draw + 2 cents (this will mean the 7th chord sounds rough, but sounds better as a single note. You can even tune it a little higher if you prefer that sound)
6- & 10-draw 1 cent higher than 4-draw (i.e. + 6-8 cents)


It's highly recommended to check that all perfect intervals (octaves, fifths and fourths) sound without interference beats. This is what piano tuners do too. You'll find it's damnably difficult to obtain constant readings from your tuner and I can only recommend playing very softly indeed and holding the note for a long time so you get a fairly clear note value. I use a Korg MT-1200 tuner with a built-in spread which tunes the upper octaves slightly sharper (as do piano tuners) and use the smallest spread the machine offers. It's hard to work to this degree of accuracy with a tuner which only shows Hz values.

Hope this will be of assistance,

Steve Baker
www.stevebaker.de
www.bluesculture.com







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