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Has anyone converted a rotary tuba to string linkage?

I once had a bass trombone (Bach Strad 50B3) converted from mechanical to string and it was great.

I have a Mirafone 186 BBb which the s type linkages are great but another thread got me wondering....

Thanks in advance for replies.

As a former horn player of 30 years, I'd only own string linkaged horns. They are far smoother than mechanical linkage and easier on the bearings as they create less of a side load when the valves are actuated. Yamaha had the best linkage, they started the articulated arm with string they are fast and smooth. Before then most horns had a solid bent arm with string.

NDSPTuba wrote:As a former horn player of 30 years, I'd only own string linkaged horns. They are far smoother than mechanical linkage and easier on the bearings as they create less of a side load when the valves are actuated. Yamaha had the best linkage, they started the articulated arm with string they are fast and smooth. Before then most horns had a solid bent arm with string.

Both the Walter Sear and the Marzan tubas have an articulated string-bar. I can't see anything else working well.

As far as converting to strings.... there needs to be a lot of consideration given to the diameter of the stop arm vs. the mechanical advantage of the paddle levers. The stroke of the paddles on the string-operated rotors on my Marzan is very short... about 2/3rds of the paddle stroke of a Miraphone. It's very important to balance the rotary motion and the linear motion and I'm just guessing that one should allow a lot of time for prototyping rather than to try to use engineering principles.

When I was in college I had a school issued Miraphone 186 BBb with string linkage. The valves on that horn were incredibly fast, smooth, and quiet. To this day, I have yet played a tuba that could match that old tuba and I often wonder why they stopped making them.

JJ

Sounds like someone (if interested and serious) should get in touch with Miraphone, or one of the US vendors who are very friendly with them. Maybe Miraphone could supply parts?

I had a Sear-Cerveny Piggy CC with string linkage for a while, and felt that the mechanical advantage was wrong. It was set up for very short finger stroke, which made those huge solid rotors seem more massive and sluggish than necessary. I made bushings to enlarge the part that the string wraps around on the rotor shaft. That lengthened the finger stroke and made the valves seem lighter and faster.

I gave up on rotary valves because for me they need cleaning just as often as pistons do, but require a lot more effort to clean.