Posted by Lew on February 07, 2002 at 17:02:30:
In Reply to: Re: Re: A grab-bag of questions (about bore). posted by Rick Denney on February 07, 2002 at 12:42:22:
Just for kicks I measured the dimensions of my BBb tubas. Here's what I found:
1934 Conn 22J -
24" recording bell, 46" tall
Bore through all valve slides - 0.770"
Bore in tuning slide 0.770"in - 0.840" out
1893 Distin BBb -
18" bell, 34" tall
Bore through all valve slides - 0.689"
Bore in tuning slide 0.720" in - 0.760" out
1931 Besson Class A Prototype BBb -
15.75" bell, 39" tall
Bore through all valve slides - 0.665"
Bore in tuning slide in leadpipe - 0.665" in and out
Bore in tuning slide after valve cluster - 0.670" in and out
1999 Conn International/Cerveny 686 BBb -
17.75" bell, 38" tall
Bore through all slides - 0.795"
1967 Conn 20K sousaphone -
26" bell
Bore in all valve slides - 0.734"
Bore in tuning slide - 0.734" in - 0.770" out
The interesting observation I make from this is that the taper of the tuning slide, which I assume indicates the overall taper, has a lot to do with the playing characteristics of the horn. The easiest blowing horn I have is the Distin, where the tubing begins its taper as soon as it leaves the valve cluster. The least open horn is the Besson, which has a very long leadpipe with a tuning slide in it, and a straight bore for quite a bit after the valves.
All this is a long way to say that in addition to the bottom bow, height, bell size, and length of the leadpipe, the rate of expansion of the branches past the valve cluster seems to have a significant impact on the way a horn plays. I would be interested in other observations on this.