Re: Compensating / Vented


[ Follow Ups ] [ Post Followup ] [ TubeNet BBS ] [ FAQ ]

Posted by Cazz on December 05, 1999 at 09:15:13:

In Reply to: Compensating / Vented posted by Clueless on December 04, 1999 at 14:24:03:

"Vented" has been adequately explained in the other follow-up posts.

"Compensating"

It is a system which was designed to keep fingering consistant from one octave to the next (into the "fourth-valve register") The way this is achieved entails building the instrument with wee little valve tubes in ADDITION to the normal valve tubing that is engaged when a valve is depressed. These extra tubes usually stick out of the back of the pistons, and they only come into use when the relevant valve is used IN COMBINATION with the fourth valve. i.e. if you were to press first valve and fourth valve, the first valve's little extra compensating valve would also be opened, slightly flattening the overall pitch.

Without compensating tubes, one has to use "semitone-down" fingering on most notes to achieve the correct pitch. Plus, you end up with a "gap" in range (the note before the first genuine "pedal" or fundamental note). e.g. C sharp on a CC instrument, or B natural on a BBb, or euphonium.

Playing and owning both compensating and non-compensating tubas, I prefer NON-compensating, because once you are going around all those extra corners and kinks when you add the extra little compensation tubes, it can make things a bit stuffy. And it's no problem generally to "semitone-down" finger, and even to pull slides to get some notes. A fifth valve also enables more alternative fingering choices in the "fourth-valve register" and makes compensating tubing unneccessary.

I hope this hasn't been too complicated (or too simple) and that it may have been helpful to someone!


Follow Ups: