Robert Barns mentioned using an electronic tuning device for music
boxes.  I first would assume that he's talking about replacing teeth or
corroded leads.  I had an interesting discussion about a month ago on
the subject with Nancy Fratti and we both agreed that the electronic
tuning device might help with the basic tuning but final tuning should
be done by ear only.

In the 1830s-1880s, when most antique music boxes were made, they
didn't follow a fixed scale, so that presents its first problem: you
don't have the fixed reference point.  You would need a tuning device
that can be tuned to a tone.

The next problem comes when you take the extremes of the box: they were
all tuned by ear and would have variances similar to a piano -- the
importance being of relativity, not of absoluteness.  To tune an entire
musical box according to A-440 would be nearly impossible and the
results would be a disaster musically.

Where it might be helpful is if there is lead corrosion in the bass
notes.  Nancy told of a sublime harmony box that had total lead
corrosion that was brought to one of her advanced classes.  They first
worked out the scale that was most likely and built new leads and tuned
it accordingly with a tuning device.

The result was a box that sounded mechanical.  Why?  Sublime harmony
boxes have two or three combs usually tuned with slight dissonance
between them to enhance and enrich the music.  This must also be taken
into account when tuning these boxes.  The same is true of a double
comb Regina, for example.  (I don't know the difference between the
combs).

In short, I would recommend using a tuning device only to rough tune
a tooth, the final tuning should still be done by ear.

Eliyahu Shahar