TubeNet

I don’t have such CC, yet those playing with this set-up may be able to help me out.

As told in a previous thread I by sheer accident am ended up with a Jos. Martin of Würzburg CC with 4 rotors (dimensions in the league of an Alex 163).

The 4th valve lowers this tuba a major third (=23), and the slide cannot be pulled for lowering a fourth.

I have pulled the 4th slide so that 24 gives a perfect fourth. The tritone has to go with 14 (a bit sharp), the fifth with 234.

Maybe I could be inspired to something better from those used to the 2-step 5th valve.

Klaus

Dunno if it helps much, but 2 of the 3 other folks I know of in your situation had their 4th valve pipes extended to give them the extra semitone. The other already had a 5th valve so he didn't bother.

The horns - 2 Sanders and a (Helleberg? Geib?) Conn rotary job.

The 4th loop sits inside the frame of the large branches in a fashion not allowing for a plain lengthening. An extension shall be offset calling for two bends for each branch. Not easy with the 0.800"+ bore tubing.

I have an idea for a redesign to happen eventually, but wanted a temporary fix through re-fingering.

Klaus

Just think everything from Eb on down, down a 1/2 step:
If you would conventionally use 4, use 2+4 on this tuba;
If you would conventionally use 2+4, use 1+4, on this tuba, etc.

http://galvanizedjazz.com/tuba.html

This might be MORE information that you are actually seeking but the above website has the answer to every imaginable valve combinatin tuning question.

Read the article and then play with the spreadsheet.

I think that there was a brief period in time when a double whole step fourth valve was mildly in vogue. Perhaps there is a theoretical benefit but I'm not sure what it would be.

My fifth valve is tuned as a sharp double whole step. Fingering that you might find helpful: 125=Db and F# below the staff. This is a slightly flat fingering for the Db.

Good luck and let us know what you find the pros and cons of such a setup to be.