Marzan Tuba linkage conversion

[Dan Schultz]

Due to the fact that the string curves all the way around the stop arm, a properly-adjusted string both pushes and pulls in each direction

Lee... there is no way a string can 'push'. Aside from that point, a string linkage lacks one thing present in all link mechanisms or Du-Bro set-ups... FRICTION! All the link mechanisms and spherical couplings have more friction that the string actions. I'm gonna have to agree that the string actions are far more effecient. Now.... is someone can figure a way to cost effectively put ball bearings into rotor axles... that's a different story!

[Kevin Hendrick]

I am, once again, totally in agreement with Joe on this. I played a string-linkage Cerveny for several years, and the biggest hassle I had with it in the 1970's was finding sufficiently-good and dependable string. 80lb test monofilament fishing line was recommended to me, but in the winter where the instrument came in- and out of a subfreezing environment, the strings would break if I did not allow them to warm up sufficiently.

I had the same problem when I first got mine. Used 40lb monofilament for several years; it worked well, but would break after about a month. Finally looked closely at the break, and found that it was fracturing diagonally where it wrapped around the stop arm. Reasoning that it was the large diameter that caused the problem, I switched to 20lb mono, and that lasted about a year, but felt too springy under my fingers. For the last few years, I've still been using the 20lb mono, but double-stringing the valves. It still lasts about a year between re-strings, but has a firmer feel ... and a built-in backup: when one string breaks, it's the one that was slightly tighter than the other, so the remaining string still has enough service life left to finish the rehearsal/concert/whatever.

I am in the process of restoring a string-linkage Marzan tuba at present, and the original string-action linkage will remain on the instrument, after it has been properly repaired. I plan to use the modern Yamaha yellow string, which has a healthy diameter and is quite strong and smooth in action.

Glad to hear you're keeping the original linkage. Thanks for the tip on the Yamaha string!

I believe that string linkages should be repaired, not amputated!

AMEN to that!

[Kevin Hendrick]

Now.... is someone can figure a way to cost effectively put ball bearings into rotor axles... that's a different story!

The bearings are available ... cost might be a different matter. Didn't ask for quotes, but one place that does sell miniature ball bearings can be found here:

http://www.qbcbearings.com/bearings.htm

There are undoubtedly others -- this was the first thing that came up when I searched. This place has plain ball bearings as small as .040" I.D. x .125" O.D ... that sounds like it would be small enough! Might also want to look into tapered roller bearings (or cylindrical needle rollers, for that matter -- not sure how much end force is exerted on rotary valves, but I suspect it's not much). I'm also wondering how prevalent the use of dissimilar metals is in the plain bearings our existing valves use -- might not increase service life, but would decrease friction somewhat.

[Kevin Hendrick]

For those who (for whatever reason) don't have access to Yamaha accessories...or choose not to purchase Yamaha accessories...

Here's a company that's been right here in l'il ol' Memphis fuh-evuh...' all sorts of various weights of braided line. Commercial fishermen thoughout the world know of this place:

http://www.nylonnet.com/

bloke "who bought a big fat spool of Yamaha line, never would consider using monofilament on rotors, and feels the suffering of those who do"

Thanks, Joe -- much appreciated!

[Tubaryan12]

Is there a way to have the Uniball on one end and the string on the other? That would seem to be the best of both worlds?

[Chuck(G)]

Well holy cow, guys!

If y'all think that string llinkages are so nifty, why not offer a retrofitting service to get rid of those nasty sluggish uniball linkages and replace 'em with nifty string linkages? It'd be a neat cottage business and probably generate more revenue than soldering lug nuts onto rotor caps.

Admittedly, the excuse that the old linen string keeps breaking is now moot. I thread up horns (and my two string linkage tubas with 70 lb test braided dacron leader (100 yards for cheap will keep you doing those conversions until the Second Coming). I will say that the dacron leader string NEVER broke during the entire time I used it--that stuff is tough.

Guys, if you're so convinced of the advantages of string over uniball (or any other type of linkage), let's see you do it by example. Lee can sell his Rudis with retrofitted string linkages and Joe can convert that prized B&S F tuba of his to strings. Ars artis gratia, what?

As my part of the bargain, I'll gladly post a photo of my string-to-uniball converted Alex.

Just foolin'with you until I can come up with a practical demonstration of what I mean....

[Dan Schultz]

Now.... is someone can figure a way to cost effectively put ball bearings into rotor axles... that's a different story!

The bearings are available ... cost might be a different matter. Didn't ask for quotes, but one place that does sell miniature ball bearings can be found here: http://www.qbcbearings.com/bearings.htm

I was sorta joking about the ball bearings. It's not a good application because the ball circuit would only travel about 90 degrees... not enough to keep the lubrication distributed throughout the bearing. Berg makes some neat miniature stuff but the Du-Bro links are the most practical units I've found.

[Tubaryan12]

Ok.....the votes are in....I'll keep the strings....thanks to all that commented and helped out....2 main things helped me decide...1st - my 3rd and 4th valve...they are absolutely quick and quiet since i adjusted the strings on them (thanks Bloke) and I am having the bearings looked at on the other 2 next week...with that adjusted and a few other tweaks I think they will be just fine. 2nd - there is something to be said to leaving a horn in original condition .... especially if there is no reason to change anything.

[Lee Stofer]

Chuck(G),
OK, you're on - most of my work these days is repairing customer's instruments, and I don't get to do much in the way of custom projects, but when I come across the right horn, I think I'll just retrofit it with string linkage, just because. . . .

With a new Rudi, I don't have to retro-fit it with string linkage. If a customer desired a string-linkage tuba, I believe Herr Meinl would build it that way on special order.

I remember fondly my first experience at Midwest in Chicago, in December 1978, when I witnessed Arnold Jacobs checking out a string-linkage custom Hirsbrunner tuba. It had the very long levers like the old King rotary tubas, and the back caps were visible from the front, the stop arms being on the backside of the horn. When Mr. Jacobs felt the valve action, the smile on his face said it all.

[Kevin Hendrick]

With a new Rudi, I don't have to retro-fit it with string linkage. If a customer desired a string-linkage tuba, I believe Herr Meinl would build it that way on special order.

Glad to know that, Lee -- I'll keep it in mind!

I remember fondly my first experience at Midwest in Chicago, in December 1978, when I witnessed Arnold Jacobs checking out a string-linkage custom Hirsbrunner tuba ... When Mr. Jacobs felt the valve action, the smile on his face said it all.

Yup ...

[Chuck(G)]

Lee, I've owned one of those old Kings and kept the string linkage on it. But I could even tell the way the valve bearings were wearing wasn't to my liking.

I see two problems with the string linkage:

1) The lever arm is located to the side of the stop arm. When the key moves, it exerts a sideways force on the rotor spindle, which is greatest when accellerating the rotor from a rest position. On small rotors, such as one might find on a horn or even a trombone, this isn't too much of a problem. But the mass of a rotor increases as the cube of the radius, while the surface area of the bearing surface increases as the square of its radius. So this sideways bearing wear can become a problem with larger heavier rotors.

2) The lever arm must move in an arc, unless there is some sort of motion translation mechanism (which would necessarily entail pivoting parts and thus another wear point). So, as the key arm travels along its arc, it, via the string, exerts an upward or downward force axially on the rotor. This I believe can also lead to unusual wear patterns.

Sure, a string linkage feels smooth--but so would an elastomer belt drive, steel cable drive or even a rack-and-pinion setup.

As a matter of fact, I've wondered about the wear patterns created by S-arms and uniball joints. If one wanted to even things out, the key arm would drive a double ended bellcrank that would be coiupled to TWO uniball linksages or S-arms--each operating on the opposite side of the stop arm in a push-pull fashion.

There's got to be a good reason that tuba manufacturers have abandoned string linkages in favor of articulated mechanical ones. A string linkage is cheaper to manufacture and has fewer moving parts.

[Rick Denney]

In the 19th century, string linkages were the rule on all rotary-valved instruments, including tubas.

Well, maybe, but I know of exceptions. One is the Cerveny Kaiserbass of around 1880, an illustration of which is in Bevan's book. That instrument has S-linkages.

Bevan also shows an illustration by Niloff in 1908 of a "Kontrabasstuba" that has rotary valves with S-linkages.

And, finally, he shows a picture of Alan Lumsden playing a late-19th-century Orsi cimbasso that has S-linkages.

My suspicion is that string linkages are less a matter of chronology and more a matter of geography. Or perhaps a bit of both.

Rick "who prefers the positive feel of solid linkages, and who is too unskilled to take advantage of speed" Denney

[Chuck(G)]

I should have refined my dates a bit. I've never seen a rotary-valved instrument manufactured between 1840-1870 that didn't use string linkages, although there may well be exceptions. I think mechanical linkages crept into use later.