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Why are piston valves bottom loading on tubas (spring underneath the valve)?

Top-loading valves are standard on trumpets (spring mounted on top of piston). It seems to be a superior system. So why are tubas different?

Is a tuba piston too heavy for a top sprung system?

Puzzled.

I've got a small Eb tuba with top-sprung valves.

I think when you get to the size of tuba valves, it simply doesn't make any difference if they're top-or-bottom sprung. And bottom sprung results in a much shorter valve casing (which is probably the real reason).

I guess I've never really seen how a top sprung valve works. Anybody have a pointer to some pictures? (Cartoons work better for me than descriptions, usually)

My trumpet has springs under/below the valves, and I've never seen one that was made any other way.

AndyL wrote:My trumpet has springs under/below the valves, and I've never seen one that was made any other way.

Most trumpets today have springs on top of the valves, but I have seen trumpets, cornets, and flugelhorns with bottom sprung valves too. Conn even used bottom sprung valves on some trumpets with a pin on the top, like on the short action, 20K/J valves. I also have a valve trombone, made in about 1900, that has top sprung valves, although most valve trombones I have seen have the valves on the bottom.

Top sprung valves have the spring sitting on top of the valve, usually in a metal sleeve, with a tab on the bottom of the valve that sits in notches on the inside of the casing. When you press down on the valve it compresses the valve between the top of the sleeve and the tab across the bottom, so that the valve body is moving away from the spring. This requires a much longer valve casing because you need space at the top of the valve for when the spring isn't under tension, but also need space at the bottom for the valve to move into. With a bottom sprung valve the space above the valve can be minimized. (I'm not sure if this explains it very well, but just look at most trumpet valves and it is obvious)

I don't know why one would think that top springs would always be better. I guess that the design guarantees that the spring is centered, but that's the only advantage that I can think of. It would certainly make for a very long valve casing on a tuba, although probably not any longer than the casings on most compensating tubas. On the other hand, a top sprung, compensating set of valves would have huge casings, if it could even be made.

Lew wrote:I don't know why one would think that top springs would always be better. I guess that the design guarantees that the spring is centered, but that's the only advantage that I can think of. It would certainly make for a very long valve casing on a tuba, although probably not any longer than the casings on most compensating tubas. On the other hand, a top sprung, compensating set of valves would have huge casings, if it could even be made.

I can think of two reasons why top-sprung valves might be prefered.

The first is pretty obivous. It keeps the spring out of the gunk and saliva that inhabit the lower end of a valve casing.

The second is that the top-sprung valve works not by pushing the valve up from the bottom, but rather by pulling it up using the valve stem. So what's the difference? Suppose that a bottom sprung valve has a bit of play (from wear or lousy manufacturing). I'd think that exerting a pull centered on the top of the valve might lead to less chance of binding on the return stroke and result in a faster return.

OTOH, I've seen an old top-sprung cornet where the spring was stretched (not compressed) when the valve was pressed. It had a strange feel, but it worked.

Ask any trumpeter and they'll likely tell you that they can tell the difference between top- and bottom-sprung valves.

Just a thought or two.

Top-sprung pistons are heavier that bottom-sprung ones due to the taller mechanism. A tuba piston is already quite heavy by comparison. I wouldn't want the extra weight. Piston speed, y'know. It don't matter how fast your fingers go if the pistons don't follow.

OK OK I found it myself:

http://www.usd.edu/smm/UtleyPages/Utley ... html#parts

Look at this link for a discussion of different types of brass instrument valves -- WITH PICTURES.

Great link. It doesn't show square (actually cube) valves though. Steve Dillon once showed me a valve trombone with those valves. I don't remember exactly how they worked, but they were some of the strangest things I have seen.

Henry wrote:Top loaded valves have a rather small effect on overall length requirements...

I can understand all of your other points, but top loaded valves mean that the total length of the casing must be longer by the length of the spring, which is about half of the total height of a bottom sprung casing. Therefore, a top sprung valve casing would be about a third larger. This seems significant to me.

I think the basic reason the trumpets have top sprung valves is because the air passageway enters the valve casing near the bottom. Picture the path of the air as it leaves the mouthpiece. It goes through the leadpipe, through the tuning slide and is now at the bottom of the valve casing so at some point someone figured that "hey if we put the spring on top, then the holes can be on the bottom half of the valve." I think you guys are tryng to make more of this than what is there. The ony proble I see wiht bottom springs is that they sometimes make noise if theya re not seated in the valve cap correctly.

ken k

Here is a shot of two French Eb tuba pistons--both about the same 0.620-ish bore size. Note that the top-sprung one is about a third again as tall as the bottom-sprung one.

The very tall valve casings might well explain why we don't see them on tubas more often:

Chuck(G) wrote:Here is a shot of two French Eb tuba pistons--both about the same 0.620-ish bore size. Note that the top-sprung one is about a third again as tall as the bottom-sprung one.

The very tall valve casings might well explain why we don't see them on tubas more often:

Hey, Chuck! I don't understand your post. It seems to me that the casing would be roughly the same length because the spring has to be someplace, doesn't it?

I think the best reason for tubas not using top-springs is that it would increase the piston weight to a point where it would affect the piston travel speed adversely.

TubaTinker wrote:Hey, Chuck! I don't understand your post. It seems to me that the casing would be roughly the same length because the spring has to be someplace, doesn't it?

Nope, consider:

• The space under the piston iin the casing's going to be pretty much the same, since the piston has to move through the same distance in either model. Most of the compressed length of the spring in the bottom-sprung version will be tucked into the recess in the bottom of the piston.
• However, take a look at the spring and its housing on top of the piston. The casing has to be large enough to contain the piston and the housing. And we can't do away with the housing since we're still compressing the spring contained therein on the downstroke. If we were stretching the spring on the downstroke, then the top- and bottom-sprung versions could be the same size.

Hope this makes sense.

Chuck(G) wrote:

TubaTinker wrote:Hey, Chuck! I don't understand your post. It seems to me that the casing would be roughly the same length because the spring has to be someplace, doesn't it?

Nope, consider:

• The space under the piston iin the casing's going to be pretty much the same, since the piston has to move through the same distance in either model. Most of the compressed length of the spring in the bottom-sprung version will be tucked into the recess in the bottom of the piston.
• However, take a look at the spring and its housing on top of the piston. The casing has to be large enough to contain the piston and the housing. And we can't do away with the housing since we're still compressing the spring contained therein on the downstroke. If we were stretching the spring on the downstroke, then the top- and bottom-sprung versions could be the same size.

Hope this makes sense.

OK... I'll kinda give you that one. However, I still say that the major problem is the piston weight. All that stuff on top of the top-loaded spring adds a lot of mass.... OK for small pistons but deadly for tuba-sized pistons.

How about:

To fit the same travel in my Nirschl-built 3302's pistons by using top springs instead of the original bottom ones, they would have to extend from the instrument over an inch further than they already do.

That's not necessarily a problem for playing, but it would be scary when I'm walking around a band room or through a doorway.

bloke wrote: A customer of mine (who is known world-wide for playing Japanese-made gold-plated trumpets) actually prefers his "student" Japanese flugelhorn (horizontal slides / top-sprung pistons) to his "professional" gold-plated Japanese flugelhorn (vertical slides with triggers / bottom-sprung valves). If you have an idea to whom I'm referring, this instrument was given to him when he was seven years old...(so if you want to play a wind instrument as well as some of these young protégé string players, starting to play just as early as they do may be one of the untapped secrets).

In a past life, when I played trumpet, I owned that student model Yamaha Flugel. I had friends who had all of the "good" flugels (Benge, Courtois, Yamaha 6XX and 7XX series). Once they played my YFL-2XX, they were blown away.

- Better intonation.

- Freer blowing.

- More flexible sound.

- Easier "switch".

If I were to ever buy another Flugel, thet would top it the list.

BTW, the valves do make a significant difference in the feel. This was just an additional benefit from this model. Again, this made it an easier "switch" not only because of the blow, but the ergonomics and tactile feeling of playing and using the horn.

Henry wrote:I take it all back. Have a nice day, I'm going off to have a nice beer.

Bottle or can?

Mudman wrote:

Henry wrote:I take it all back. Have a nice day, I'm going off to have a nice beer.

Bottle or can?

No, the question is, "Bottom loading or top loading?"

Yeah, it applies to beer...

No, the question is, "Bottom loading or top loading?"

Yeah, it applies to beer... [/quote]

or rather bottom fermenting or top fermenting.....