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For most front action piston tubas there's three places a 5th valve can go.

Before the valve set: same or small bore

After the valveset: same or bigger bore

After the main tuning slide: Bigger bore

Im wondering which one produces the best results? One would think putting it right after the tuning slide with a larger bore would be the best option, but not all tubas have that?

On all my projects I put it after the MTS (large side). Just makes more sense to me, FWIW

In terms of ergonomics, the split valve setup might work a little bit better because you can mount the valves a little lower on the body. It’s probably better for linkage setup also as the fifth can be located just about where the thumb is.

For manufacturing, I can see why the B&S and MW sets are/were laid out in the single cluster. It probably reduces the amount or complexity of assembly jigs needed and allows for the sets to be grafted on to a bugle design a bit more readily.

I know the gnagey tubas always have a valve right after the valveblock. Is that because of the convenience of the tubing being already there?

Typically...
Placing them on the large side of the main slide on a front-action tuba only delays the dogleg taper, rather than (less desirable) shortening the main slide's tuning range (the most demonstrative example of this - arguably - being the M-W 2145) or dropping the main slide bow down to the bottom of the instrument, and in harm's way (as happens with the 2165).

Otherwise, placing them in the mouthpipe tube works (as Yamaha has proven), but more people seem to "freak out" when that is done...
...and (well...) placing a 5th valve into a mouthpipe tube doesn't offer that desired "CSO York appearance", does it?

On the YCB-822, their first “York-like” tuba, the rotor is after the pistons.

On the YFB-621, the rotor being first seems to offer no issues. That is a supremely open blowing horn, at the cost of other qualities.

The Kalison horns had the rotor after the valve block, but the routing was backwards. I don’t know if this is bad design, but the other inconsistencies of this brand seem to prevent anyone else from copying the design.

There’s probably some marketing aspect as well. Typically fifth only gets employed in the low register and manufacturers directly (and incorrectly) tie larger bore valves to freely blowing response. So putting fifth after the block somewhat demands this to keep a progressive taper going. My 188 did fine with fifth first with the 2-3 combo and a single bore through the cluster.

Marketing, engineering, and science don’t always coexist in the same space.

matt g wrote: ↑Fri Nov 20, 2020 9:16 amMarketing, engineering, and science don’t always coexist in the same space.

Sadly,
Far too much narrative propaganda is presented, today, as "science".
Even more sadly,
A large percentage of the masses except the rhetoric, and never question it.

I believe you guys, but can someone explain to me why a larger bore 5th valve wouldnt be more open and free flowing helping the low-range stuffyness.

I think all tubas are (shall I say) less open with all 5 down.

LargeTuba wrote: ↑Fri Nov 20, 2020 2:10 pm I believe you guys, but can someone explain to me why a larger bore 5th valve wouldnt be more open and free flowing helping the low-range stuffyness.

Because it's a common misconception that it is about free flow. Nobody cares about air flow resistance, flow speed is so slow that it easily can flow though the back bore of the mouthpiece.

All we care about is the definition of acoustical impedance at correct slotting frequency, and the best in tune overtone series, which defines the sound quality and ease of response.

The only purpose of air flow is to supply the energy needed to keep the lips vibrating, the rest is about slotting, resonance and response, which is defined buy the acustical properties of the instrument.

Brass instruments sound productions don't rely on the flow of air.
The flow of air (particularly in a tuba) is nearly nonexistent and very much parenthetical.
Brass instruments' sounds rely on sympathetic vibrations of columns of air.
The fact that air escapes through our vibrating lips - when this occurs (again) is almost a non-factor.
The reason that "air leaks" mess up the vibration of the air column is because the affect the vibration, and not because they affect the flow of the air.

The more air that is used up in making our lips vibrate (due to [a lack of enough?] resistance) the harder we must work to make out lips vibrate.

bloke wrote: ↑Fri Nov 20, 2020 10:48 am

matt g wrote: ↑Fri Nov 20, 2020 9:16 amMarketing, engineering, and science don’t always coexist in the same space.

Sadly,
Far too much narrative propaganda is presented, today, as "science".

Agreed! It's almost as bad as the amount of science being presented as "narrative propaganda".

Sorry about the thread sidebar, back to the 5th!

I've never owned a horn with a 5th valve. But since playing more euphonium these days, I wish I had a better way of playing a low Eb on my YEP-321 (4-valve non-comp). Lipping up 124 works but its still a bit low and the tone suffers.

As just one example, imagine abusing the New England Journal of Medicine to misrepresent and scare people off an effective and inexpensive therapeutic, just because a politician - that a screed-composer dislikes - mentioned that well-respected doctors told him how effective it is.

I just put it there (after MTS crook) because:

1 - there's usually more cylindrical tubing there that can be spared, giving you more "pull" on the MTS

2 - it frequently makes the rotor linkage less complicated and "Rube Goldberg-esque", and somewhat more "direct"

3 - it allows for a larger bore on the valve (you can debate the rationale/physics of this all you want, I like the idea)

4 - with proper planning, there's less conflict with other valve circuit tubing, making it easier to lay out, including making it detachable, which leads to:

5 - a fixed 5th valve, with its sometimes awkward angle, on a front-action piston tuba can present difficulties in servicing, not only the valve itself, but getting to the bottom piston valve caps in back (assuming that's where you are putting the 5th valve circuit)

I can't think of anything else at the moment, but I think that's enough (at least for me, anyway )

Oh yeah, almost forgot:

6 - it makes the horn look more "York-esque", which has been likened to "tuba design bordering on art"

Id be curious to learn why @the elephant decided to move the 5th from the leadpipe to after the mts.

Other than the desirable york looks.

This is a GREAT discussion, thank you. I have played tubas with the 5th valve in all locations, INCLUDING in series (dependant) with the 4th valve. In terms of how they play, I would offer that it is more about the INSTRUMENT, than the placement of the valve. I would guess the best way to test theories, truly, would be to use the same tuba, and move the valve to the different locations. Then, an evaluation can be made. Your thoughts on this??

tclements wrote: ↑Sat Nov 21, 2020 8:11 am This is a GREAT discussion, thank you. I have played tubas with the 5th valve in all locations, INCLUDING in series (dependant) with the 4th valve. In terms of how they play, I would offer that it is more about the INSTRUMENT, than the placement of the valve. I would guess the best way to test theories, truly, would be to use the same tuba, and move the valve to the different locations. Then, an evaluation can be made. Your thoughts on this??

Generally speaking, this would be a good idea except for one variable - the location of the valve will dictate the size of the valve, so you would need to have at least two separate valves (the bore of the large side of the MTS, and one smaller one for the other side that would also work before the valve set, in the mouthpipe).

Interesting concept, but just too much work for my taste

Tony mentioned it . . . The fourth option in this is the dependent 5th. Not without its advantages/disadvantage. Bore size and MTS length then become an entirely separate discussion.


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The other important factor would be where in the bugle that pesky valve sits, node-wise. On one of my horns, I do get some sympathetic vibrations from the rotor on one note (but it’s not audible farther away).

@Yorkboy, EXACTLY this is WAAAY too much trouble for what it might prove, or prove nothing. Potentially, one would need valves of FOUR different bores: 1 - in the leadpipe. This has to be smaller than, or the same size as the first valve. 2 - Right after the valve cluster. This has to be the same size as, or slightly larger than, the 4th valve. 3 - IN the 4th valve tubing. This, out of necessity, has to be the same bore as the 4th valve tubing. and 4 - after the MTS. The bore on this valve is totally dependant on WHERE along the main bugle you can fit it, but LARGER than the valve cluster. It HAS to be placed where it won't disrupt any of the nodes in the main bugle. Like I said, a total PIA!!! The R&D on this must carry an ASTRONOMICAL cost. Hat's off to those hearty individuals who work hard and long, and invert TONS of dough on horn development. JUST so we have decent instruments to play.