Let’s talk about … rotor bumpers

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Back in the day we called them “corks” because they were always natural cork (and fell apart pretty regularly), but today “bumpers” seems to be the preferred term.

Horn-bumperQuite a variety of these are available. I for years have mostly been using O ring or drive belt material, but I was feeling not completely happy with the results, and there was too much noise associated with the bumper material on several horns I regularly use.

At the risk of going Scientific American on our readers, there are quite a variety of options out there for bumper material. The article and list over at the Siegfried’s Call website (here) is the most comprehensive I know of, with materials including Buna-N, soft Neoprene, Silicone, and more!

I opted to buy from them their soft Silicone in the .210 diameter, which they describe as follows—

Softest feel with a little bounce particularly with lighter springs. Very little noise, if any. Fairly durable and resistant to oils. Our shop favorite feel.

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The first horn to get it was the ASU Chinese Wagner Tuba which had certainly a very hard bumper material from the factory. It made a HUGE difference! The second horn to get the treatment was my own main double horn, which I also felt had valves that made more noise than they should. Again, it made a noticeable difference. Initially it seemed just by a degree, but the more I played it the more my horn felt like a higher end horn! Bumper material does impact your perception of the feel of quality of a horn.

The big picture point being that quiet valves are possible!

I think people these days tend to use bumpers too long that are from materials that tend to harden over time, slowly creating extra noise. Don’t rule out a change of bumper material to reduce your valve noise.

University of Horn Matters