Modding 4th valve tubing

[Tubadbadu]

Hello, so I have this old Lignatone/amati 6/4 Bb tuba with 4 rotary valves. It is a great tuba but 4th valve is very stuffy. I am wondering would it help if I replaced 4th valve tubing with a larger bore? Right now the bore on all valves is the same, if my measurements are correct. Also would I need to replace the whole valve? Thanks for any reccomendations.

[bloke]

Here are the "have you checked to see if it's plugged into the wall?" questions:

- rotor alignment?
- rotor leakage (often caused by a "repair tech") ?
- leaky solder joint or rot hole(s) somewhere in the circuit?

[tubatodd]

Here are the "have you checked to see if it's plugged into the wall?" questions:

- rotor alignment?
- rotor leakage (often caused by a "repair tech") ?
- leaky solder joint or rot hole(s) somewhere in the circuit?

@bloke serious question, have you ever seen any rotor witness marks put on by a factory that are actually off? in other words, from the factory, the rotor is marked for misalignment? I've got to think that is rare but not unheard of.

[the elephant]

I have seen several Cerveny and B&S stencil instruments where they were carelessly struck, so that the die bounced, leaving two marks nearly overlapping and giving a "blurry" look to one of the two marks.

[BramJ]

My Amati 6/4 has an aftermarket 4th valve. It is an "open wrap" and not stuffy at all.

[arpthark]

Random thoughts/observations that may or may not be applicable to your situation (if the rotor is properly aligned and all the stuff bloke said above):

"stuffy" is a subjective term.

Sometimes, the problem isn't too much resistance, but not enough resistance. I think of the big York style 6/4 CC tubas, one of which I own and two of which I played recently (a demo model Eastman 836 and a very well preserved Hirsbrunner HB-50). The bore size on the fourth valves and the fifth valves on these tubas is quite large, but the low range can be, for want of a better term, "stuffy." I don't think valve bore size has a lot to do with it and the problems are elsewhere in the instrument, which is overall a very large horn.

Last thing. The low C on German style F tubas can be finicky. Your big Cerveny Kaiser is essentially a blown-up F tuba (in proportion/wrap), and those issues can still persist with your big BBb's equivalent low fourth-valve F. Some folks have had some success by "sleeving" the inner bore of the fourth valve tubing, making it smaller and introducing a bit of resistance into that circuit.

Edit to add that the Cerveny/Amati/Lignatone 6/4 kaiser bore is 21.2mm (.834"). That is already very large, and I don't think you'll easily find a meaningfully larger rotor.

[iiipopes]

And in addition to what bloke said, have you cleaned the valve circuits thoroughly so there is no obstruction, slime, gunk, or anything else that can impede anti-nodes? Maybe a brace re-attached in the wrong place? Nodes are where essentially no vibration takes place; antinodes are the points where resonance takes place. If an anti-node is impeded, it is essentially similar to damping the note, much like touching the strings of stringed instruments to damp down their sustain. This is not a function of the diameter of the tubing. And as posted above, you aren't going to find anything with a larger bore anyway.

[bloke]

Here are the "have you checked to see if it's plugged into the wall?" questions:

- rotor alignment?
- rotor leakage (often caused by a "repair tech") ?
- leaky solder joint or rot hole(s) somewhere in the circuit?

@bloke serious question, have you ever seen any rotor witness marks put on by a factory that are actually off? in other words, from the factory, the rotor is marked for misalignment? I've got to think that is rare but not unheard of.

plenty.
When I'm in huge hurry (going through school stuff) and a hit a crappy Chinese rotary tuba with stupid marks, I sort of instinctively know which one is "good" and eyeball 90% from that. Personally-owned tubas (typically) are not b.s. tubas, so most of those marks are reliable.

[Tubadbadu]

Here are the "have you checked to see if it's plugged into the wall?" questions:

- rotor alignment?
- rotor leakage (often caused by a "repair tech") ?
- leaky solder joint or rot hole(s) somewhere in the circuit?

@bloke serious question, have you ever seen any rotor witness marks put on by a factory that are actually off? in other words, from the factory, the rotor is marked for misalignment? I've got to think that is rare but not unheard of.

I have not checked any of this things, all I did was clean it the best I could. Thanks for the advice, it is much appreciated.

[Tubadbadu]

My Amati 6/4 has an aftermarket 4th valve. It is an "open wrap" and not stuffy at all.

So did you only change the rotor or the casihg as well?
Also where did you buy an aftermarket rotor? I can't seem to find it on the internet. I will first check for any leaks/missaligments, but if that does not work I would try to change the rotor. Thanks for the reply

[Tubadbadu]

I have seen several Cerveny and B&S stencil instruments where they were carelessly struck, so that the die bounced, leaving two marks nearly overlapping and giving a "blurry" look to one of the two marks.

Thanks for the answer I will check for missaligment.

[Tubadbadu]

Random thoughts/observations that may or may not be applicable to your situation (if the rotor is properly aligned and all the stuff bloke said above):

"stuffy" is a subjective term.

Sometimes, the problem isn't too much resistance, but not enough resistance. I think of the big York style 6/4 CC tubas, one of which I own and two of which I played recently (a demo model Eastman 836 and a very well preserved Hirsbrunner HB-50). The bore size on the fourth valves and the fifth valves on these tubas is quite large, but the low range can be, for want of a better term, "stuffy." I don't think valve bore size has a lot to do with it and the problems are elsewhere in the instrument, which is overall a very large horn.

Last thing. The low C on German style F tubas can be finicky. Your big Cerveny Kaiser is essentially a blown-up F tuba (in proportion/wrap), and those issues can still persist with your big BBb's equivalent low fourth-valve F. Some folks have had some success by "sleeving" the inner bore of the fourth valve tubing, making it smaller and introducing a bit of resistance into that circuit.

Edit to add that the Cerveny/Amati/Lignatone 6/4 kaiser bore is 21.2mm (.834"). That is already very large, and I don't think you'll easily find a meaningfully larger rotor.

I believe there is too much ressistance, the problem is indeed with 4th valve low F and lower. When you play the 4th valve it just does not want to take air. Now at first I believed that I just have bad technique. But I had my ex professor, who is a very good and succesful tuba player with different orchestras, to try it and he came to the same conclusion. Now I do not see how sleeving would help, but I guess sometimes the opposite of what looks logical could work. Since I have no knowlege of the tuba design/build you answer seems very interesting. Thanks for your reply

[Thattubaguy345]

Broken solder connections or braces can also contribute to those kinds of issues.

[BramJ]

My Amati 6/4 has an aftermarket 4th valve. It is an "open wrap" and not stuffy at all.

So did you only change the rotor or the casihg as well?
Also where did you buy an aftermarket rotor? I can't seem to find it on the internet. I will first check for any leaks/missaligments, but if that does not work I would try to change the rotor. Thanks for the reply

It was done before I bought the tuba, so I don't know the details, but the bore of the 4th valve is the same as the others