Question about valve "popping"...???

[Bandmaster]

I did a search of the old archives and didn't see an answer to this problem. I recently had the rotary valves vented on my BBb tuba because the the valves were popping when depressed, especially 1 & 2. They were very tight and pressure (or vaccum) was being held in the valve tubing. That basic popping is now gone, BUT I still have a really noticable "popping" when I go from Ab to G or G to Ab, both at the top of the staff and at the bottom of the staff. When I add or release the second valve there is no way in hell to get an even slur, just an annoying pop! But C to B and Eb to D is just fine, no popping at all. Also Ab to G below the staff has NO popping. I find this VERY confusing!?!?!?! Do any of you have any ideas on what could be causing this phenomenon? I have checked with the repair tech that vented the valves and he is equally confused. The slides don't create suction when pulled, so where could the pressure that is being released come from? Could the valves somehow be misaligned? I visually checked them and they look fine to me. Any help would be greatly appreciated.

[Bandmaster]

Is this popping sound like air being released or is it more mechanical in nature?

It sounds like air being released (or captured ???), but it is NOT mechanical.

What kind of horn is it and what kind of linkage does it have?

It is a Sanders Custom, a copy of the Miraphone 191 BBb. Stainless steal ball joints with screw attachment. The valves are very fast, smooth and quiet normally, except for this problem.

Do you feel any movement in your fingers when this popping occurs? Like the rotor is moving when it happens?

It happens when I depress or release the second valve, so yes the rotor IS moving. But I can also feel the pop in my middle finger tip. It is from the vibration created by the release of the air, not a mechanical click.

Is the linkage securely fastened to the top of the valve?

Yes... I double and triple checked. I even tried taking the linkage loose and rotating the valve 180 degrees and reinstalling the linkage.... no change...

What kind of shape are the rotor stops in? Are they rubber, nylon or cork? Do they have any excessive wear?

Excellent shape... rubber... no...

If the action is nylon ball and socket are they excessively worn or is there any additional play in them?

Stainless steal... Very little wear... no excessive play...

What happens when you play the Eb on the staff and go to the D using a 1&2 fingering?

Nothing... it plays nicely... I tried that one too...

Are you tilting the horn differently when you play high?

Nope... it stays steady all the time...

I hate to ask this, but is there any possibility that the issue is on the other end of the mouthpiece? I'm not trying to be a jerk, but it would seem fairly unusual to only occur between Ab and G and NOT Eb and D.

I have played on MANY other horns and do NOT have a similar problem. I think it is really odd too, that's why I am taking the time to ask questions. No offense taken. I used to have an old Miraphone 186 with linkages shot to hell, and the second valve never popped on it. My local repair tech felt it when he played it too, but he had no suggestions.

Make sure that you post the answer when it finally is discovered. Where is Rick Denney, Bloke and Dan Oberloh when you need them?

I will... I am only playing this horn while Dan Oberloh is restoring my Holton 345. But I live a thousand miles from him, so I don't take the "little" stuff to him to fix. Hopefully someone will have had a similar problem once upon a time or somebody will think of something to try.

[Rick Denney]

Where is Rick Denney, Bloke and Dan Oberloh when you need them?

I would answer if I had any idea what the problem might be.

If the C-to-B slur is smooth but the Ab-to-G slur is troublesome, that would seem to me to conclusively reject the hypothesis that it is the valves causing it.

More likely, there is an aspect of the design of that instrument that makes that slur difficult, and the pop is the result of your efforts to overcome the difficulty. It's possible that this problem was covered or misinterpreted as the pressure in the valve branches which led you to vent the valves in the first place.

And sometimes valve venting will cause a slight leak to the outside during the valve change, and that may be what you are hearing. The vent hole should be placed very carefully to prevent this (Bloke writes that he places the hole slightly above the center of the ports, where the valve has more seal surface with the casing).

None of these explanations really answer the symptoms, though. Leaks usually uncenter the instrument enough to make slurs easier rather than harder.

Try putting some tape over the second-valve vent hole. If you still hear the popping, then it is something else. That might also help you identify whether the air-escaping noise is coming from the bell or the vent hole.

Rick "with no clear solution" Denney