Posted by Klaus on May 27, 2002 at 15:15:19:
In Reply to: CoolTubas.com posted by Dale on May 27, 2002 at 14:40:41:
Of being conical
A pic of Dales is interesting.
One reason for the 3+1 piston system is, that the distance between the 3rd and 4th pistons allows the main tubing expand in bore to reach the desired bore of the 4th valve tubing.
The Martin pictured solves that problem by the odd "valve loop" (really part of the main bugle) leading from the 3rd to the 4th valve.
Klaus
PS: For the sake of Tim I add the link to Dale's page