Responding to Jim Heyworth's questions re tuning disc box combs:

Disc box combs are not inherently "Sublime Harmony" as the two combs are
structurally identical with respect to tooth shape and dimension.  They
may be, and I suspect frequently are, tuned slightly different from each
other resulting in a slow beat on the order of 1 or 2 Hz.  We have a 17-
inch Stella that shows marked beats of this order and it sounds
beautiful.  Whether the combs were tuned this way deliberately or just
done quickly without a lot of testing is open to debate but the end
result is pleasing anyway.

They should probably not be tuned equal temperament.  The combs may
approximate a mean or just temperament.  Since musical boxes play in only
one key or its relative minor, the tones can be optimized for the best
harmonic presentation.

A few (very) samples of some disc box combs here show stretching on the
order of 10 to 20 cents per octave.  It is difficult to really quantify
this sort of thing as musical boxes sometimes show little stretching in
the mid range octaves but the lower octaves will be stretched more to the
bass and the upper octaves will be stretched more to the treble.  I have
measured some early key wind boxes that showed stretching on the order of
25 cents per octave across the comb.  It seems insane but the boxes all
sounded just fine and quite brilliant in tonal quality.  If the box
sounds good I would leave it alone.  And thereby hangs a story.

Some time back I worked on re-tuning a key wind comb that had been sanded
on the surface to improve its looks I suppose.  The result as you can
imagine was an acoustic and musical horror.  Oddly enough, with the
exception of some really wildly off pitch teeth, the main effect was to
raise the treble end such that the stretching (I use the term loosely)
was on the order of 40 cents per octave.  This made the notes at the top
roughly two and a half steps higher than the bass end.  They were even
too high for my old Conn Strobe tuner to register.

It sounded terrible ... except that after working on other problems and
playing the box over and over for a couple of hours, the dang thing would
begin to sound okay!  But leave it alone for a day and my ear would
return to "normal" and it sounded horrible again.

Message: our ears and psychological receptors to music can be trained to
accept odd or unusual harmonic relationships as normal.  I have thought
about this a great deal and now limit work on really bad combs to short
periods.  It pays to be cautious.   The end result of this comb was to
reduce the overall stretch to about 20 to 25 cents per octave and of
course correct any teeth that were obviously off pitch.

Jim, you are on the right track and have already transposed Graham Webb's
data to your own situation.  All combs may be a bit different from what
is reported in the books.  Good luck with the rest of it.

Chuck (current mossback of this group) Walker¶
cewalker@prodigy.com¶
Hopewell Junction, NY