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On tuba and sousa pistons, the springs are loose at the bottom of the valve casings, with the pistons sitting on top. You have to line up the piston guide with the casing groove/channel before you can screw on the top cap before being able to depress the valve.

On trumpets, the springs are within the semi-enclosed chamber at the top of the pistons. You can just drop them in the casings and screw the caps on, then twist the pistons until they click in place, with the guides 'clicking' into the channels.

I once talked to a trumpet player and told him tuba valves are not like that. He thought it was sort of stupid that we have the springs loose in the bottom of the casings and that we have to line up the guides before screwing on the caps, being able to then depress the valves.

Discuss...

These aren't tuba valves, but they do belong to a euphonium I owned recently

I have seen both tubas and trumpets (well, cornets actually) made with both top and bottom valves.

All modern trumpets and cornets have the springs at the top.
Some vintage models may have them at the bottom.
All modern flugelhorn (I think) have them at the bottom.

I much prefer the top springs, I hate the bottom ones in ly flugelhorn (alignement and stuff).
However, the bottom springs work nicely on my Eb tuba.

claf wrote: ↑Sun Apr 13, 2025 11:27 pm All modern trumpets and cornets have the springs at the top.
Some vintage models may have them at the bottom.
All modern flugelhorn (I think) have them at the bottom.

Modern Flugelhorns can have either bottom (Yamaha and others using the Couesnon design) or top (Bach, Benge, Conn, Courtois, Getzen, most Adams and Kanstul) springs. Just a small correction.

For tubas, I can see top springs working for top action (compensating) tubas if they use the short action model. However, weight and tolerance could be issues (see Conn 20J/K). Not sure how top springs could be implemented in a front action design, though, due to clearance.

Thank you for the correction.

Top-sprung piston valves of that size are a very bad idea. This is probably why you do not see them being made. Bottom-sprung pistons are much shorter than top-sprung ones. If you scaled trumpet valves up to tuba size, they would be between eight and ten inches long.

The worst issue is a reduced technique for the player due to the hugely increased weight. They would be much harder to press due to the much stronger springs needed to shove nearly 60% more dead weight up about an inch and a quarter. They would be much slower for the same reason: weight.

Not sure why you say that bottom sprung small valves would be a bad idea. My 1950s Conn cornet has bottom sprung valves and I've never had any problems with it. It is a student director model too.. so it wasn't like it was a top end model with super tight manufacturing tolerance.

The answer to your question is this:

When very large pistons are built in that way, all that stuff has to be carried on board with the piston - just as with a trumpet piston. Trumpet pistons don't weigh very much and are small, so it's not that difficult to carry all that material along with the piston.

Carrying all that stuff with a tuba piston would add weight and require even stronger springs than tuba pistons already require.

I didn't read Mark's response, but he's probably telling you that his Adam's pistons feature that set up. I've seen them in some marching baritones and euphoniums. That's probably borderline use of that system. It certainly would dictate using as much aluminum as possible - certainly the stem assemblies. The nuisance with the marching instruments that are set up this way is that they aren't cared for it all and the stems rot and break or - even worse the threads rot off screwed together with the rest of the stem assembly breaking off.

EDIT: I see that Wade already explained this, so apologies for redundancy.

gocsick wrote: ↑Mon Apr 14, 2025 7:45 am Not sure why you say that bottom sprung small valves would be a bad idea. My 1950s Conn cornet has bottom sprung valves and I've never had any problems with it. It is a student director model too.. so it wasn't like it was a top end model with super tight manufacturing tolerance.

Cur-and-paste error. Just the first word was backward, and the only thing that I changed.

Fixed!

I suppose tuba pistons made like trumpet pistons with the semi-enclosed top spring system would make them very long/tall. But I'd still like something better than loose springs in the bottom of the casings, under the pistons.

It's just a little annoying at times to line up the guides before being able to screw the caps down. And especially annoying to try to 'center' the loose springs under them so they won't make spring/click sounds every time the piston(s) are operated.