TubeNet

An "FB Friend" from Brazil asks:

I've noticed that the Eb tubas or Sousaphones tend to have a 0.687 bore and a little bigger, and I've seen up to 0.822 on BBb instruments.

Of course, there are BBb tubas with much larger bores than 0.822.

Is there a limitation to the diameter of the bore on Eb tubas and sousaphones?

My 1938 King 1236 has a .687 bore. which is the same as their 1240/1241 models according to http://www.hnwhite.com/Low%20Brass.htm" target="_blank which tells me they made common materials to fit all of their horns. Incidentally this is also the same bore as the Eastman EBC632 CC which a lot of people seem to like.

My .562 Eb valve thing has a really good low Bb. A's a little tighter but not an issue.

York monster E flat tubas (as well as the 19" bell flare BB flats) are .656, same as the Conn 2,3,4 & 5J horns.

I've also seen similar pitched and sized Holtons with that same bore.

bloke wrote:Some of the front-action non-comp. Eb tubas feature larger bore sizes, (2141...PT-22P...etc...) It doesn't seem as though folks brag on the intonation characteristics of those tubas, but I wouldn't necessarily rush to use "the bore" as the "whipping boy" for the intonation characteristics of those models.

I agree with bloke, in that the bore is not as important regarding intonation, as is bugle taper and bell throat diameter.

(I have a secret theory that selection of bore size, at least in the old days, were not necessarily made for only sonic reasons.)

The Besson 983 may have the 4th valve sitting in line with the 3 first valves, but the air doesn’t go directly from the 3rd piston to the 4th piston. There is a detour loop allowing for the same bore expansion as the distance between the 3rd and 4th pistons in the 3+1P configuration.

Klaus

bloke wrote:
Some of the front-action non-comp. Eb tubas feature larger bore sizes, (2141...PT-22P...etc...) It doesn't seem as though folks brag on the intonation characteristics of those tubas, but I wouldn't necessarily rush to use "the bore" as the "whipping boy" for the intonation characteristics of those models.

So far (??), I haven't found any Eb tubas that play better in tune than some of the 3+1 comp. designs, and yes.........

The 3+1 designs do have nice intonation. My old imperial even better than new sovs.
As for the larger bore ones....2141/2040-5/PT-22 I find them to have a very pleasant intonation. Especially the first two (spent less time with the pt-22), but! The 3+1 Miraphone Ambassador (.709-.740) was probably better than they all.

imperialbari wrote:The Besson 983 may have the 4th valve sitting in line with the 3 first valves, but the air doesn’t go directly from the 3rd piston to the 4th piston. There is a detour loop allowing for the same bore expansion as the distance between the 3rd and 4th pistons in the 3+1P configuration.

That detour loop is actually because the 983 was developed by simply moving valve on an earlier British cavalry tuba (with 4th valve separate) to in line. I know the actual cavalry tuba used for development.