| Ai,
The first maker to make bottom vave caps a variable was Dave Monette. I can still remember the phone call when he figured it out. I don't know how it relates to horns that are made by other makers, however. It was pretty specific to the balance that made his horns unique at the time.
First it was the weight of the valve caps and then he came to understand that the tightness of each cap contributed to creating a similar tension between each casing.
Still with me?
What he figured out had to do with the amount of mass on each valve that came from the amount of tubing that each valve had and how the combined weights affected the response of the horn. The 2nd valve has considerably less combined weight than the 3rd does. See why? 3rd valve and slide are less mass than the 2nd, right? In order to equalize the tension between the two you have to change the tightness of the bottom valve cap. The 1st is right between the other two.
When I tried that with conventional horns I found the results weren't at all the same. In fact, I just decided that all it did was make them more unstable. It's a "whole- horn" concept you could say.
So, the bottom line is that with Monette horns, people who buy them (or the cynic might say "buy into them") learn to manipulate the caps in a pre-prescribed way that changes slightly depending how tight you feel on a given day. For other brand horns I don't know what one would do because I have no experience trying that in recent years.
ML |