Eb Bore

[Steve Marcus]

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?

[tubapix]

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.

[Bob Kolada]

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

[roweenie]

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.

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.)

[imperialbari]

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

[Lectron]

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.

[Wyvern]

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.