Hi Matt,
I don't remember Daniel Wolverson's discussion - I'm glad to see it
now...
I actually only remembered it because I just authored an article with
Balázs Nagy on the tekerő that we submitted to a journal and I
wanted to cite some information on the buzzing bridge's physics that
Frank Vickers had passed on from his own discussions with Wolverson.
The bits I needed happened to be in the same location as that
response from Wolverson, so I knew right where they were from having
seen them last week.
I feel as if I've tested this idea - I "fixed" the chien by simply
holding it down to keep it from buzzing and continuing to crank as
if I was attempting to buzz... no drop in pitch. Anyway, doesn't
his test condition describe the permanent condition of all the
other non-buzzing strings?
That's what I thought, but I passed on his message in toto in case
there was something useful. However, I have noticed that on my gros
bourdon, if there is too much pressure on the wheel, does exhibit the
effect Wolverson described.
This is more interesting! It's true, this is an effect that
harmonica players use (I've never been able to bent pitch *up* on a
harmonica!). But in this case we're not talking about two
similarly tuned reeds vibrating simultaneously, nor are we talking
about two separate bowed strings resting on the same bridge. Do
you suppose the same effect applies with only one string on the
bridge, and that being bowed on only one side of the bridge?
I don't know much about this, but I think that it ought to be
testable if one can figure out how to put mass on the other side of
the bridge without making it so that the bridge doesn't buzz.
In reading your original post where you describe the problems and
what is going on, and the responses, I have a few other things that
might be worth trying:
Regarding the drone strings that break into high harmonics, this
sounds like a problem I had. The solution was replacing the strings
with a different kind of string that was not as stiff:
Here are some things to consider:
1. Is the string you are using too heavy or stiff? On my tekerő I had
a HEAVY and STIFF gut bass drone that had the problems you described.
Replacing it with a lighter gut-core, copper-wrapped string (made by
Balázs Nagy) took care of the problem totally. A string that is too
stiff will want to vibrate at a higher pitch than one that is not as
stiff because the displacement along the string is smaller if the
string is vibrating at the harmonic than at the fundamental.
Tightening the string can take care of the problem, but loosening it
results in a very poor sound.
2. Are you using enough rosin? Insufficient rosin can do what you
describe. You are an experienced player, so I don't think this is the
issue, but it's worth asking.
3. Are you using too hard a rosin? I know everyone else is telling
you to move to a harder rosin, but your rosin has to be tacky enough
to really pull the heavy drone strings. Think of the difference
between bass rosin and violin rosin: what is ideal for your
chanterelles is harder than what is ideal for your low drones. You
may need to go to a rosin that is softer than what is ideal for the
melody strings in order to meet the demands of your drones.
Regarding the dog that drops in pitch, have you replaced the dog at
all? I think that the people pointing to changes in weather may be on
to something. Even inside my house I detect a lot of seasonal wood
movement and have noticed real effects on a number of my instruments.
Note that Neil's attribution to high heat and low humidity can just
as likely be the other way around: it all depends on what the
instrument is stable at. Changes either way can create problems. You
may find that you need different dogs for different seasons.
I don't know how helpful any of this is, but I think you can probably
take care of the drones by trying different strings and you then have
only one problem to deal with...
-Arle
