Hi Graham-
Just before I received your message, I sent my own message asking about
many of the things you comment on. Oh well. Thanks for the information -
it's very interesting! I would love to have been there when those tests
were being done.
At 03:10 PM 7/27/2006 +0100, you wrote:
I know the chien buzzes at the trompette string pitch
I have seen oscilloscope traces of this (uni research project)
Its a nasty square wave with lots of contact bounce
The fundamental is however the string pitch
The usual pitch drop may to be due to the increase in sounding length
while buzzing
This was always my assumption, but then why I don't find that the pitch
drop is "usual" for most hurdy-gurdies?
When not buzzing the length is defined from the ear to the chien
When buzzing the length is increased by the distance between the chien
notch and its fulcrum on the mouche bridge
The chien notch is no longer the node point
I did some measurements on the pitch drop - chien length
The numbers worked out pretty well
I'm not sure I follow this at all. The fulcrum is the point where the
mouche bridge meets the soundboard, the "pivot-point" of the chien,
yes? On my hurdy-gurdy, that distance is about 1/2 inch. Why would the
string's vibrating length increase by this distance, a dimension
perpendicular to the line of the string? I don't get it. Is it something
you can explain, or did the numbers just happen to come out this way?
Short chiens produce less pitch drop
Hmm. What do you mean by short? Height of the notch off the soundboard,
or distance between the notch to fulcrum? The latter I think would conform
to your earlier statement. I can make a chien that's very close to the
soundboard ("short") but with a much longer notch-to-fulcrum distance.
A complicating factor is that light, crisp trompettes produce much less
pitch drop
I guess this is due to the chien foot staying more in contact with the
belly and the node moves less
Hmm. By light do you mean low mass? Does a chien of low mass actually
stay "more in contact" with the belly than a denser chien?
~ Matt
