compensating rotaries

[MaryAnn]

Somebody explain to me (probably again?) why you can't make a compensating rotary valved instrument?

[Ferguson]

There are many examples of compensating double French horns and double Wagner tubas with rotary valves.
-F

[marccromme]

There is the compensating Lätsch 3+1 rotary euphonium (the fourth valve being a quart valve Bb/F) , and the Cerveny compensating 4+1 rotary tuba ( the fifth valve being a quint valve F/Bb). Not often seen, but absolutely possible to build.

[MaryAnn]

Ok I stand corrected. Next question, is why aren't they out there? I really hate the usual fifth valve that is a flat half? step, and find a compensating system MUCH easier to play in tune. But my hands just do not work with pistons larger than a trumpet, and so I always play rotaries. Being a horn player, "stuffiness" is not something that bothers me, and in any case can be overcome much more easily than, for example, the low C on a lot of rotary F tubas. At least by me.

That tuba in my new picture is not the BAT it appears to be but my new Norwegian Star, which does not look big on a normal sized person.

[tclements]

Alexander made (makes?) a CC/F Compensating double. That is, it is an F tuba, when you hit the switch valve it goes BACK through all the f tuba tubing PLUS the valves a second time. So it is not a FULL double like most F horns, but in CC it is a compensated CC. Make sense?

[marccromme]

... and the Cerveny compensating 4+1 rotary tuba ( the fifth valve being a quint valve F/Bb). Not often seen, but absolutely possible to build.

I remembered wrong. It's a CERVENY F/Bb-TUBA HARMONIA 4+1+1 valve setup, valves 1-4 normal in right hand, 5th in left hand thumb, and 6th (the switch from F to Bb) in right hand thumb. Pretty weired setup in two respects:
5th valve in left hand and switch valve in right hand, and also quint switch. This is probably due to the German/Austrian/Tchech tradition of playing F and Bb tubas, and not Eb and Bb as in UK, or F and C as in DK and US (I believe).

As for the 5th valve, one sees layouts with large half step, large whole step and 2-tone step (same as 2+3). All of them have advantages and disadvantages, all of them can't be tuned perfectly without slide pulling. So having easy slide manipulation on the lowest combinations is an asset.

My setup has a large whole step, that works pretty fine for almost all combinations, except for the low Gb, F and E before the pedal Eb.

[cjk]

Ok I stand corrected. Next question, is why aren't they out there? ....

The rotors are twice the height normal rotors would be and are therefore twice as heavy. This makes for either slow valves or heavy springs. Tuba valves are already slow when compared to trumpets and euphs. They don't need to get slower.

[imperialbari]

At least the Alexander compensating F/CC or F/BBb tuba in my eyes suffers from one major design flaw:

The switch valve is the first valve after the leadpipe.

As the CC (or BBb) compensating loops have a larger bore than the F valve loops, the placement of the switch valve implies a retrograde bore progression, when the switch valve is activated. The air passes through the wider bored compensating loops before it passes through the narrower main valve loops.

That easily could have been remedied by placing the swith valve as the last valve, after the main valves.

Klaus

[imperialbari]

I really hate the usual fifth valve that is a flat half? step.

You are bound to hate the fifth valve, if you finger, as if it lowered the main bugle a flat half step.

It lowers the main bugle a flat whole step.

With an Eb tuba the point of the fifth falve is to tune its slide, so that the low Abis in tune fingered 45.

[MaryAnn]

I just coulsn'r remember what it was, flat whole or flat half. I actually wrote flat whole to start and then thought, no, that isn't right, must be a flat half. I'm learning a whole new set of fingerings, since Eb is the only key tuba I've never owned before. So I'm not even to the point of using the 5th valve yet and will eventually figure out where it fits down low. But... my Mphone 184 CC had a 2+3 fifth valve and I liked that a LOT, because I like to use one-valve fingerings as much as possible, for intonation. My MW 182F had that weird 5th valve that is a flat whole step, and I never found it workable for me. It seemed like I was trying to lip everything once I got down into that range, plus the F tuba stuffiness. The Star is WAY easier to play than the 182 was, even though it is much larger.

[windshieldbug]

The rotors are twice the height normal rotors would be and are therefore twice as heavy... They don't need to get slower.

The bearing surfaces on the top and the bottom are about the same size, so I don't know that they're necessarily slower, but the effort required to start moving twice the weight means either a much longer throw for the paddles to give you the mechanical advantage needed or much stronger springs.

Neither is exactly "user friendly" in MA's case

[MaryAnn]

I'm trying to remember the brand of (french) horn that has plastic rotors. They are really quick, but they are not tuba-sized. Ah, it is Finke horns that have plastic rotors. However, I get it that the tuba application would be clunky at best.
I wonder what it would cost to get a 2+3 5th valve slide made for my Star....but am in dreamland, I'm sure. Nobody here (Tucson) can do that, and it can't be done without the tuba and be sure it will fit.

[marccromme]

I really hate the usual fifth valve that is a flat half? step, and find a compensating system MUCH easier to play in tune.

Mary Ann, yes, a 3+1 compensated piston tuba has easier to remember fingerings in the lowest octave before hitting the pedal tones than a 5 valve rotary tuba. Buuut ... compensated tubas are not necessary easier to play down there.

In my experience they get more stuffy down there where you use all valves ona 3+1 compensated than the 5v rotary tubas I tried, probably because using all 3+1 valves means using 14 (!!! yes, think and count: three valves four times and one valve twice ( 3*2 + 1)*2 = 14) valve port passages, whereas a 5v rotary only comes up to 10 valve port passages (each valve twice). And because the common 3+1 compensated brass band tubas tend to have a smaller bore than the Norwegian Star you are playing.

As for better intonation, that is true to a certain extend, but for most tones this is on a 5v tuba easily overcome by choosing your compromises wisely. I do like this:

1) tune main tuning slide such that Eb (0 valve) overtones are smack on (at 442Hz, which is our pitch in the band). That means Bb dead on, Eb upper octave very slightly flat, and Eb lower octage very slightly sharp.

2) tune 2nd slide slightly flat on D overtones (same differences as above)

3) tune 1st slide slightly flat on Db overtone series

4) check that 1+2 C overtones are slightly sharp (some prefer dead on), but very usable. Re-iterate 1) - 3) if necessary

5) tune 3rd slide slightly flat on 2+3 B overtones series

6) check that 1+3 Bb overtones are slightly sharp (some prefer dead on), but very usable. Re-iterate 5) if necessary

Up to this point there is no difference between 3+1 comp and 5v rotary setup, now the differences start

7) tune 4th slide slightly flat on Bb overtone series. This way you have two Bb's to choose 1+3 and 4, depending on musical context

check that 2+4 A overtones are slightly sharp, but very usable. Reiterate 7) if necesary

9) tune 5th slide slightly flat on 2+3+5 A overtone series

10) check that 4+5 Ab overtones are slightly sharp (or dead on, if you prefer). Re-iterate 9) if need be

11) check that 2+3+4 G overtones probably end slightly flat, but very usable. Re-iterate 7) if need be

12) as for Gb, F and E just over pedal Eb .. well you probably need to work out your own tubas fingerings and slide pulls for these.
These will end more or less off, unless you pull slides. On the other hand, I never had the need to use them in the Eb Bass Brass Band setting I am playing.

Using these tunings, and getting used to the 5th valve fingerings, a good 5v rotary is (almost) as well tuned as a 3+1 comp, but probably less stuffy in the lower range. Except for Gb, F and E just over the pedal Eb.

I can't say anything about tuning the 5th valve to 2 whole steps (never tried), except that you are missing the slightly flat version of A overtones (2+3+5), and you are missing the slightly sharp (or spot on) version of the Ab (4+5) overtones. To get Ab overtones tolerable, you need to tune the 4th valve pretty much flat making Bb overtones no fun, and which will make the 2+4 A overtones flat. I am not sure what you will win in the lower register with a 2 whole steps (= 3+2) 5th valve.

There are some really nice fingerings with the above setup in the sharp keys, for example E major gets E (2+3+5), Fsharp (2+3) Gsharp (1) A (2) B (2+3) Csharp (1) Dsharp (0) E (2+4) (1+2 is too flat on my tuba). B major uses almost the same nice combinations.

I suggest you try to tune as explained above, and give the 5th valve a chance, it's really a nice setup once you get used to it.

[imperialbari]

In my opinion the main reason compensating instruments are perceived stuffy in the range right above the open first partial is all about intonation.

Fingerings 134 and 1234 are only partially compensated. The compensating loops compensate for the addition of the 4th valve, but not for the errors coming from combining the 3 first valves.

On my euphonium I had a main tuning slide installed that allows for a precise intonation of low concert C and B natural. No stuffiness at all.

I would have liked to install a similar trigger on my British made Besson 981, but the main tuning slide is too short for that purpose. The problem could be solved by venting the 3rd piston and put a trigger on the 3rd main slide. But I am not sure local techs can do the venting safely.

[Ulli]

The compensating loops compensate for the addition of the 4th valve, but not for the errors coming from combining the 3 first valves.

That's why I use a 3v comp. Boosey&Hawkes BBb Tuba in Brass Bands.

[Ferguson]

I wonder what it would cost to get a 2+3 5th valve slide made for my Star....but am in dreamland, I'm sure. Nobody here (Tucson) can do that, and it can't be done without the tuba and be sure it will fit.

That's a stock part from Miraphone. I think it costs a few hundred dollars, is made to order in 30+ days, and plugs right into your horn. It's easy to get one.

-F

[J.c. Sherman]

It's in fact quite easy to manufacture a double compensating rotary tuba. But there's a special, as yet untried (almost) challenge: different bore sizes on the two sides.

On compensating Euphs and Tubas (British style), the 4th valve has a larger bore, and the additional ports in the pistons for the additional tubing is set at that larger bore as well. For this to work on a rotary tuba, the top and bottom sides of the rotors would have to have different bore sizes, ideally. This isn't unattainable... Paxman horns have stacked double rotors with two different bores. That would be beyond cool on a tuba.

Making a full double tuba has an additional challenge: having the the change valve ahead of the main valves. The only person/fabricator to address this was Dr. Fred Young, who - rather than having a 6-port double rotor - had two 3 port rotors. I believe he managed to get stacked rotors with two different bores built which had the longer tubing expand after the first change valve, pass through the stacked rotors at a larger bore, then return to a larger change valve. Brilliant, but prohibitively expensive and numbering 1 examples.

This would be a little more difficult on a double bass/contrabass... I know he's built one, but I don't know if this idea carried over... I haven't seen it yet.

Oh... and a full double weighs a ton.

My dream would be a Besson 17" bell compensating with 3+1 in rotors for the shorter, faster stroke. Where's that winning lottery ticket so I can make Meinlschmidt my minion in that project?

J.c.S.

[imperialbari]

The makers name escapes me now, but there has been a rotary compensating double tuba made, which had the change valve after the four main valves.

I even think this tuba came to my knowledge via a discussion here on TubeNet.

The only problem I see with that design would be the long connection between the left hand near the top bow and the change valve near the main tuning slide.

Could be solved by letting the connecting rod pull the rotor crank, and then letting a spring near that rotor pull it back again when released.

Klaus

[Sam Gnagey]

Here's a photo of a couple of F tubas I had. The one on the left is a Miraphone Viennese system and the one on the right is a Yamaha compensating double F/CC that was reportedly made for John Fletcher.

[imperialbari]

Did the Yamaha F/CC double have 2 valves lowering it a whole step? A shorter one for G as a 5th partial and a longer one for Bb as a 6th partial?