TubeNet

I'm kicking around the idea of building a cimbasso in BBb, using a 4 valve King .687 bore set.

One thing (among others) that has eluded me about these horns is the physics of the mouthpipe, in regard to its layout.

With that in mind:

Is it critical to have it enter the 4th valve, incorporating a long stretch of cylindrical tubing (as is usual on rotary valve cimbassi), or can it enter the 1st valve, as is normal for piston valve tubas? Meaning, does this set up give the horn its characteristic sound, or is it just for reasons of convenience or "tradition"?

What is the "traditional" or "usual" length of the tapered section of the mouthpipe, and what is the taper like?

I know the first question may be difficult to know, but any theories would also be appreciated....

bloke wrote:My only answer is "because I tried this, and it worked"

THIS is why Tubenet is so

The last cimbasso (in E flat) project I tried, had a short "tuba-like" mouthpipe, going directly into the 1st valve - although it worked well and played fine, it did not have the "characteristic sound" I was looking for. It basically played like a weird-looking tenor horn pitched in E flat.



I believe you have the goods here.

It will make the job more difficult (the 1st valve port is "hemmed in" by other valve circuits) but I believe it will be worth the extra effort.

What is the mouthpipe O.D. where it enters the bass trombone receiver, and do you think a small size E flat receiver would work as well?

I'm sure the quality of those rotary valves are top-notch (I think I know where you get them) and I could do the same, but I'm not a great fan of rotary valves - and the use of piston valves adds to the challenge

(tubing the mouthpipe into the 4th valve port is no challenge - it's making the connection from the 1st valve to the bugle that is the fly in the ointment, as you already know)

I will have to dig up your cimbasso construction post and study your photos closely

bloke wrote:That severely-bent crook (the same one that causes water-drainage problems from the #4 circuit of King tubas) could be used (no?) as part of the routing to get the air column exit (from the #1 casing) over to the "bell side"...??

Hmmm.....