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Thayer Valve Tuba

Postby IsaacTuba » Tue Jan 08, 2019 2:56 pm

Is it possible to construct any kind of valved brass instrument using something besides rotary/piston valves? If so, what would the benefits be? Perhaps even Hagmann valves if you can fit them in there.
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Re: Thayer Valve Tuba

Postby djwpe » Tue Jan 08, 2019 3:42 pm

There is a Haag cimbasso, made with Hagmann valves. I’m not sure what the point is. The Thayer valve especially is a bad valve from a mechanical standpoint, as the bearing surface is also the sealing surface. I had a trombone with an extremely worn Thayer valve, and the only thing that could be done is replace the valve. No servicing or rebuilding was possible.

The Thayer seems to offer some advantages in feel on trombone, though rotors seem to be catching favor again. I think the open feeling that trombone players desire (and get) from the Thayer is not something that would benefit a tuba.

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Re: Thayer Valve Tuba

Postby ASTuba » Tue Jan 08, 2019 4:57 pm

There has been a lot of work to make the Axial Flow valve (also known as Thayer) be a better valve, thanks to the fact that it has become so popular with players. There is a new version of this valve, called the Infinity Valve, that can be purchased here:

https://instrumentinnovations.com

This valve has sealed bearings on both ends of the valve, and it's amazing how little wear there is on the bearings in this. I've seen this valve hooked up to a cordless drill, drill turned on for 30 minutes, and there is no heat at all in the valve casing. Truly a fantastic product, only available currently on the Bach Trombones with the AF at the end of the model number, as far as I know.
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Re: Thayer Valve Tuba

Postby the elephant » Tue Jan 08, 2019 7:22 pm

Many years ago, Mr. Thayer told me of a euphonium he was working on using four of his larger valves. It did not ever pan out because the action of the Thayer "axial flow" system was just to heavy and slow and the stack of four made the wraps of the bugle nearly as tall as those on a tuba. The normal way to stack these is to reverse every other one, like on a bass bone. Otherwise the slide loops become unworkable. To use four would require some space between 2 and 3, and they already have a good bit of space between the two on a bass bone. Take a very careful look at a bass bone with twin Thayers. You will see that to fit them closer together you would have to introduce sharp bends into the the tubing… which 100% negates the purpose of the Thayers in the first place.

Add to that the wear aspect mentioned above and you can see why Mr. Thayer never decided to market this idea. Meaning that this idea was floated by a lot of people for many years, including Mr. Thayer, who gave the final and most important thumbs-down to the concept, since he flatly stated the he would not make his valve in the needed bore sizes after having experimented with such a beast.

Further, to make tuba valves they have to be large. To make tuba valves without distortions or pinches in the bore they have to be VERY large. Willson has made all-Rotax-valved horns for many years. They do not sell nearly so well as his piston horns because the Rotax valves are larger in diameter. This means the parts that make mild contact when they rotate have a lot more surface area, so they are much slower than smaller diameter rotors. You can do a lot to fix this, but the lighter you make a really large rotor the more fragile it becomes. I have a very nicely made Kanstul "CR" valve that is unusable because it is so light and skeletonized (actually using brass tubing in a hollow rotor body cage with a two piece stem) that being dropped one time has skewed the internals of the rotor so it no longer rotates well at all. I really like the valve but have never spend the $$$ for more because of this fragility. And they still turn more slowly than a piston can move up and down. IMHO they turn too slowly to ever be used for anything other than a low-use 5th valve; it simply, as made, would never make it as a high-use 1st valve.

The whole issue with tuba valves is fast action, light weight and full flow. You can have two, but not three, with today's offerings. But they are improving.
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Re: Thayer Valve Tuba

Postby bloke » Tue Jan 08, 2019 9:11 pm

If you take a look at Yamaha YCB-626S pistons (or even Weril 4-valve sousaphone pistons), it's obvious that tuba-appropriate valves can be made without terribly serious bore distortions in the porting - which seems to be the goal (though some of the attempts actually exacerbate, which is difficult to explain to some who champion some of them) of most of the gimmick valves.

The "axial flow/Thayer" valves are disappointing for me to work with, as the bearing and air-seal surface are one-and-the-same, and very large...so if there is any attempt to accomplish an air seal anywhere close to that found with some other types of valves, motion becomes impossible. That having been said, trombonists may not notice this, as there is a .002" space (.004" difference difference in diameter between the inside slide o.d. and outside slide i.d.) between the typical slide tubes on trombone playing slides.
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Re: Thayer Valve Tuba

Postby oedipoes » Wed Jan 09, 2019 7:00 am

I have seen a Gronitz tuba with Lätzsch or Hagmann valves (on their old website) and a Rudolf Meinl 5/4 BBb with Lätzsch or Hagmann valves.
So it can be done ...
Personally, I don't know why one would want to make the Rudi 5/4 BBb more freeblowing than it already is, I like a little bit of resistance personally...
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Re: Thayer Valve Tuba

Postby bloke » Wed Jan 09, 2019 10:29 am

oedipoes wrote:I have seen a Gronitz tuba with Lätzsch or Hagmann valves (on their old website) and a Rudolf Meinl 5/4 BBb with Lätzsch or Hagmann valves.
So it can be done ...
Personally, I don't know why one would want to make the Rudi 5/4 BBb more freeblowing than it already is, I like a little bit of resistance personally...


Even standard rotors don't distort very much:

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Some understand the explanation immediately - and others must be shown physically, but those standard-diameter rotors with round entrance/exit holes (rather "figure-8" cutouts) actually distort the bore ~more than~ do standard rotors.
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