Posted by Chuck(G) on May 08, 2002 at 11:10:09:
In Reply to: Thoughts on Yamaha 'compensating' 5th posted by Ian Easton on May 08, 2002 at 08:37:59:
While useful, a dependent 5th valve isn't the complete answer to compensation.
Consider the situation with a 3 valve automatic compensation system for a euphonium in Bb. The 3rd valve is the "master" and, when depressed adds additional tubing to both the 1st and 2nd tuning slides to bring the pitch of the instrument to G. So it really serves the purpose of 2 extra valves--one for the 1st branch and one for the 2nd.
Now, consider a 4 valve auto compensator. The 4th valve is the master and adds extra length to the first three valves. To get the same effect with a dependent valve system,you'd have to have 3 more valves, one for each of the first three. In other words, the 4th valve produces the same effect as having an extra 3 valves, one for each of the first three branches.
A single extra valve, while an inexpensive alternative, does not produce the same effect as a full automatic compensation system.