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Originally Posted by tom turner ... Probably about .030 is the norm on pro horns. Going into the local guitar shop to purchase a valve "alignment" set of felts will NOT correct for an accumulated +/- of .030" on a SPECIFIC valve!
...Plus, not all out of spec problems can be solved with felt! Sometimes a valve spring barrel must be unsoldered from the valve, then realigned PERFECTLY to get the ports lined up rotationally. Sometimes a valve spring barrel must be shortened . . . or a valve stem . . . etc.
...It is truly amazing what life can be put into an assembly line horn when a perfectionist like Wayne Tanabe, Bob Reeves, or Flip Oakes gets hold of a stock horn and fixes all the accumulated imperfections! |
Tom,
I thought I posted this before, but perhaps I didn't hit the submit button. I can understand how cumulative problems can add up. But they don't always add UP. For example, if the valve button is off .005 and then the valve stem is off .003. It might be the other direction and thus make the cumulative off by only .002. In fact, over the long haul, this would be just as likely. The statistically principal of the central limits theorem would suggest that with enough samples, a regression to the mean (average) is expected (too many years of teaching graduate statistics). Again, the central limits theorem does not directly say this, but after putting it into action it predicts the outcome.
So on a new horn, the cumulative tolerances would be MORE LIKELY to be closer to zero than the other extreme. Again, I would be upset if I paid for a new horn and a PVA was required.
The other point is what you said above. Flip can be truly amazing at bringing a stock horn "to life" by making adjustments. I have seen you and Flip post that Flip puts hours into a horn to tune it (tweak it) before it ships. A PVA is part of that tweaking if I understand it right. You talked about how a PVA sometimes requires soldering and de-soldering to get the rotational tolerances right. Does that mean that Flip will take a new Wild Thing from Kanstul and actually de-solder and solder it?
Knowing what I know about manufacturing processes and statistics, I cannot imagine a horn being out by that much in a cumulative fashion. All the errors would have to be in one direction.
Jim