Posted by Matt Walters on October 18, 2000 at 20:23:08:
In Reply to: How close is close enough? posted by John Swensen on October 17, 2000 at 15:05:17:
First, I ask the grammar and spelling police to bypass this post. Now for the rest of us who have friends, I will try to answer some of John's questions.
Misalignment of tubes as you call it, sounds like what I refer to as gaps between tubes that are joined by a ferrule. Yes, a gap can affect the way a horn plays. You will have disturbances in the air flow and yes we are also dealing with sound, not just air. The bigger the gap, the more likely it will cause a sound quality and/or intonation problem.
How much is enough? That can be a mystery. Do you like the way your horn plays and sounds? Then leave it alone. However, if there is a problem with your horn and others of the same make and model don't have that same problem, then you can logically assume THERE MUST BE A MECHANICAL REASON YOUR HORN PLAYS DIFFERENTLY.
If only the 2nd valve combinations sound or play badly, then fix the 2nd valve slide or knuckles that the outer tubes fit over. If open notes have a problem, then check out the main tuning slide first. If you find a PHYSICAL DEFECT, fix that and see what happens. Start with what is easiest and cheapest to fix.
Excessive gaps inside ferruled joints cause problems because of what else CAN occur. Burrs and jagged edges can cause some intonation problems (a big topic of itself). Solder blobs will cause response problems.
In fantasy land all solder joints are smooth with no gaps and no solder blobs. Reality is that most people don't want to pay the price for workmanship to that level. The good news is that after you reach the point of very GOOD (not perfect but certainly not some hack, either) workmanship, you will have reached the point of dimenishing returns.
Remember, some slop has to be built into the construction of the horn or it will never go together. I have never seen a tuba that didn't have a few manufacturing flaws that could have been done better.
We've just touched the tip of an iceberg on this subject.