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We all have seen tubas cut from BBb to CC very successfully. Is it feasable to cut a CC to EEb? Is it possible to go in the opposite direction and lengthen an F to EEb?? Ok, repair guys, you are on.

OK. First you need to apply the fundamental pitch lengths:

18' = BBb
16' = CC
13 1/2' = Eb
12' = F

Not exact but perhaps a little more or less depending on some other factors such as the bore.

Cutting (or extending) a valve section is not a problem going from any pitch to any pitch because the tubing is cylindrical (except in the case of a few conical bore instruments).

Common sense prevails.

The problem lies in manipulating the conical branches of the open bugle.

I've also been interested in this kind of topic specifically cutting a BBb to an F, would such a procedure create an F tuba with the same broadness in low range, or rather the same big open sound In that range while still offering the emhanced high register harmonics of an F? Or am I completely off in my thinking?

Anything CAN be done, but usually the most cost-effective way to do those "extreme" conversions is to sell one and buy the other.

EMC wrote:I've also been interested in this kind of topic specifically cutting a BBb to an F

You're essentially cutting an 18 foot cone down to a 12 foot cone. Ain't gonna work, as the resulting 'small end' won't match the bore of any valve set; it'll be way too big. You could make compromises, but relatively constant rate of flare is essential for good intonation in brass instruments.

UncleBeer wrote:

EMC wrote:I've also been interested in this kind of topic specifically cutting a BBb to an F

You're essentially cutting an 18 foot cone down to a 12 foot cone. Ain't gonna work, as the resulting 'small end' won't match the bore of any valve set; it'll be way too big. You could make compromises, but relatively constant rate of flare is essential for good intonation in brass instruments.

Unless you're cutting a tiny BBb tuba and replacing some of the inner braces.. But, then again, what's the point?...

Out in the garage, high up on top of some file cabinets is one of my uncompleted "Frankensteins" - actually my first attempt.
The carcass of the instrument is an upright Conn Jumbo EEb. The valve section from a small Conn CC. The top branch (#1) had the small end enlarge a little to smooth out the overall taper for a CC tuba. A few slide reroutings so things would fit.
It played fairly well. Pitch was ok. No worse than the Conn CC. But it did have a somewhat dead sound.

Yes, EEb to CC can be done. Actually not that hard mechanically to fit it together.
My thinking is that the EEb carcass tapers to quickly and causes issues when adding additional length. I did see somewhere some time ago a similar project starting out with a York EEb. It was for sale on Ebay about 10 or 15 years ago. Good looking instrument.

I also recall a story about Art Gold, then with the Minneapolis Symphony, who tried making CC tubas from Ebs. So the idea is not new.

PMeuph wrote:
Unless you're cutting a tiny BBb tuba

Not unless the middle part of the BBb is comprised of straight tubing (which is pretty improbable).

UncleBeer, didn't you do some Eb to CC transformations?