Very interesting Nathan!
In theory, it's a bit like the finger going 'round the wine glass, or
the glass harmonica, except some of the roles in that are switched,
especially the idea that the rotating, part is not the vibrating part
(normal for a HG) but rather its actuator. In theory it could work,
but you have a problem if the wheel is completely perpendicular: it
will contact the string in two locations, one at each outer rim
"track" (as you described it) on the diameter of the wheel. A way to
solve this, though, would be to offset the wheel's axle at a slight
axle down towards the tail of the instrument, and make the track
bevelled to match the offset angle and hence parallel with the
string. THen, it would be possible to just have the string contacted
at one point. Also, shimming and pressure adjustments could then
easily be achieved with a sliding track that goes forward and back
along the length of the axis of the crankshaft, and can be locked in
place (like with set screws or something, a type of trim control).
All of this works only if the instrument in question is intended to
play only one string at a time as chanterelle, otherwise you'd have a
problem, which you could solve (also in theory) by having a series of
gears or belts that allow for multiple wheels, one for each string),
however this brings us back to the very issue you were, I think,
intending to address. Bur for a kind of gurdy-rebab (is that
gurdybab? or would that be edible, like a skewered, droning dish?) it
should work fine.
interesting concept, Nathan!--Great to keep the old grey matter
functioning, and fun to think about our dearly beloved in new ways
and incarnations.
cheers,
Vlad
Wolodymyr Smishkewych
wolodymyrsmishkewych.com
[EMAIL PROTECTED]
On Jan 03 2008, at 18:18, Nathan Roy wrote:
Okay, this is going to be an impetuously written message. I hope I
don't make a fool of myself, but running across this concept has
got me excited. My main hobby is sitting around theorizing about
different experimental musical instruments, or innovative
variations on existing forms. Most of them are probably pointless
and naive, since I am neither a fine craftsman, nor an accomplished
player in need of daring new challenges. Anyway... please bear with
me while I attempt to describe my latest flight of fancy.
The recent thread on the ninera got me thinking about how to use a
fingerboard on a HG without messing up the tangential contact
between string and wheel rim. Then I checked out the French site
with the "vielloncelle", and that reminded me of Lark in the
Morning's "bassgurdy", which is also a keyless, vertical wheel-
bowed instrument. Now, both of these instruments appear to use
gears to two separate the crank and wheel shafts at a ninety degree
angle. Of course, this allows such an instrument to be held upright
like a 'cello, cranked in the ordinary fashion, and bowed
perpendicular to the strings. The drawback to this is that the
gears would have to be machined very precisely to allow for
sensitive cranking techniques, like tremolo or coups de poignet.
Okay, so here's my modification of this: Imagine a long instrument
with a single string, and a crank set in the side as in the
vertical HG-like objects I just mentioned. However, the wheel bow
is mounted directly on this one shaft, so that it rotates parallel
to the string, rather than across it as expected. The obvious
problem is that this bow cannot contact the string from below,
against its circular rim, since that would be a dreadfully
inefficient way to impart perpendicular vibration. Instead, the
string runs beside it, down at a level toward the axle so as to
approach forming a diameter. The bow then makes contact from the
side, bowing upward against a raised track running along the outer
edge of its flat surface.
In theory, this bow orientation should work, since friction is
still being applied at right angles to the string's long axis. But
why would anyone want such a setup, since the historical HG design
with a horizontal keyboard works as well or better than a vertical
orientation. My serendipitous conclusion is that this would allow a
fingerboard to be used without upsetting string pressure against
the bow! Since this pressure is applied from the side, and adjusted
by horizontal shims, bending the string downward should have little
effect!
Okay, I know the situation is much more complicated than this. The
string would have to meet its bridge and be deflected toward the
tail-piece before passing the wheel's opposite edge, or it would be
bowed a second time, downward. Only two chanters could be bowed by
a single disk (one to each side), and additional strings would
require a series of parallel wheels mounted on the same axle.
Drones could be stacked on top of each other, but this brings the
bow direction out or perpendicular and requires more complex
bridges. One benefit is that the vertical string vibration should
propagate efficiently into the soundboard, like a piano, making the
high violin-type bridge with its rocking impedance transfer
unnecessary.
Hopefully, some of you with more experience in practical matters of
lutherie or acoustics can point out any obvious oversights I may
have committed here. If the basic theory is sound, I think it would
be great to do some experiments with the idea! I only wish my own
skills were up to the job. (Otherwise I would have jealously
guarded my supposed stroke of genius, although I assume there are
no fortunes to be made in claiming such an innovation.) Anyway,
sorry for my habitually long emails. Tell me what you think, and
thanks for humoring me!
Nathan Roy
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