Marzan Tuba linkage conversion

[Tubaryan12]

I have a Marzan BBb rotor horn with string linkage and I am thinking about converting it to solid linkage. 2 questions:

1) Should I do this?

2) Has anyone else done it and how well did it turn out?

thanks for the help and comments in advance.


btw....Rick, the stop arm advice is great and I am leaning toward that.

[Tubaryan12]

Thanks for the advice Bloke...I think I may have been turned...I tried what you suggested and they are MUCH better.

[Kevin Hendrick]

1) Should I do this?

no.

Keep in mind, I'm known as quite the contrarian, but:

- The vast majority of high-end French horns utilize string linkage.

- There are no ball-and-socket links that are as quiet and trouble-free as string. Which is easier, readjusting a (still quiet) slightly stretched string, or trying to figure out how to remove "play" from a worn ball-and-socket mechanism?

.
.
.

String cannot make noise, and it is not "slow".

Very well said, sir! I've been resisting suggestions to switch to ball-and-chain ... sorry ... ball-and-socket for quite a while, for the reasons you gave. Also, string has a light, linear feel that I really like. String is definitely not slow!

OK, what about converting mechanical to string? Any advice on that?

Don't know what the costs & other factors would be, but it's something I would consider (for whatever that's worth).

[Chuck(G)]

Very well said, sir! I've been resisting suggestions to switch to ball-and-chain ... sorry ... ball-and-socket for quite a while, for the reasons you gave. Also, string has a light, linear feel that I really like. String is definitely not slow!

All true, but having owned two tubas with string linkage, I can say that there is a big price for this--uneven bearing wear. A string linkage puts considerably more lateral force on the bearings than does a simple ball-and-socket.

A well-aligned ball-and-socket linkage has nearly the smoothness of a string linkage, usually doesn't break and is a bit easier on the bearings than string linkage.

[Tubaryan12]

now i'm leaning back again...too much knowledge can be a bad thing

[Kevin Hendrick]

... A string linkage puts considerably more lateral force on the bearings than does a simple ball-and-socket.

A well-aligned ball-and-socket linkage has nearly the smoothness of a string linkage, usually doesn't break and is a bit easier on the bearings than string linkage.

Interesting -- hadn't considered that! The lateral force required to rotate the valve would vary inversely with the length of the moment arm (actual arm for ball-and-socket, string wrapped around the shaft for string linkage). Has anyone ever done a string linkage that used a larger-diameter attachment to the shaft (radius comparable to that of a ball-and-socket) to wrap the string around? Seems like that would put the two on more-nearly-equal footing re: lateral force required (and reduce the incidence of string breakage, as well). On the other hand, the bearings in my 1974-vintage Sear-Cerveny kaiser CC are holding up very well after 31 years of frequent use ... I suspect the materials used for the bearing surfaces could have some "bearing" (sorry) on the wear issue as well. It would be interesting to do a durability comparison between ball-and-socket & string linkages, factoring in the different bearing materials used in various instruments ... not to mention the various valve lubricants that are available.

...too much knowledge can be a bad thing

Indeed it can ... three much can be even worse!

[Tubaryan12]

With the pros and cons for both sting and uniball it makes me think of another series of questions. Did instrument makers move away from the string linkage as a fad or was there a solid reason for moving away in mass from strings and s-linkage? I know that there should be less noise in the linkage with the uniball but couldnt the noise issue be taken care of by just having the uniball on just one end and string on the other? Or was it done for a best solution to all problems (noise and string breakage)?

[Chuck(G)]

In the 19th century, string linkages were the rule on all rotary-valved instruments, including tubas. I don't think that string breakage was a major concern (if it were, something like music wire could have been subsitutued).

I've seen string linkage tubas where the top bearing was worn to an oval shape. If you think about it, this makes sense--a string linkage must be taut during its action. Since most act from one side of the rotor arm or the other, a force is exerted that becomes greater as the rotor mass gets larger. I think this is why the horn folks can get away with strings--their rotors aren't very heavy in comparison to tuba rotors. And there's wear by the string itself. On an old Alex, I see grooves worn in the stop arm by the string. And there's a matter of an axial force being exerted on the rotor because the key arm moves in an arc.

The price one pays for a mechanical linkage, of course, is that in an S-arm linkage, is wear at all of the pivot points in the linkage. If they get loose, you get noise.

If one has a uniball linkage where the wear in the ball joints can be adjusted out, I think you've got the best of both worlds.

[Chuck(G)]

String (unlike ball-and-socket) tends to have a "soft landing" at either end of the throw, as the string is quite a bit stretchier than is the steel or plastic link socket.

It's not the "landing" that causes the wear in my opinion, Joe. It's the "takeoff".

[Kevin Hendrick]

String (unlike ball-and-socket) tends to have a "soft landing" at either end of the throw, as the string is quite a bit stretchier than is the steel or plastic link socket.

It's not the "landing" that causes the wear in my opinion, Joe. It's the "takeoff".

That, of course, prompts yet another question: how much (if any) effect does the material that the valve travel stops ("landing pads", if you like) are made of (cork vs. surgical tubing vs. various synthetic rubber products) have on bearing (and linkage) wear? Seems like the amount of cushioning provided at each end of the valve travel might be an important item (aside from not being "clacky", as brass or steel would) ...

[Chuck(G)]

The fact the string (over time) wears a rut around the stop arm hints to me that (with a string) the torque is applied at as close to the very center of the rotor body as possible.

Joe, you got some 'splainin' to do. The groove means nothing more to me that the string's slipping against the stop arm surface and digging its own trench in the brass.

[Lee Stofer]

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. French horn string was too small to give a good action, and was slightly clanky.

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. 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, unlike a mechanical action that only exerts force in one direction at a time, so the string action that is properly adjusted exerts less bearing load on the valve than any mechanical action.

As Joe indicated, a clean and properly lubricated rotor moves so easily, that over 90% of the force your fingers must overcome is the valve spring tension required for quick-enough action so that the instrument can play musical passages.

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

[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.