[Harp-L] Marine Band Crossover Tuning

[Steve Baker <steve@xxxxxxxxxxxxx>]

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