Quote:
Originally Posted by Brian Gencarelli
This concept was passed on to me by a luthier I worked with in the past, and I figured with your AO/BO expertise you could shed some light? Plus this would affect the tail length to shoot for.
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I'm sure that others will disagree with me, but I personally do not believe in "tuning" the after-length. I'm not going to say that players are wrong when they honestly think that their "tuning" performed some kind of miracle on their bass, but it usually turns out that several things were changed in addition to the "tuning". My problem with it is two fold. First, I've tried just about every scheme there is for after-length "tuning" and I never found one that consistently worked on different basses. In addition, the string does not slide freely over the bridge so the "tuning" frequently changes from day to day as you actually tune the instrument to play it. Second, no one has ever been able to give me a good, logical reason why tuning the after-length to some particular interval (3rd, 4th, b5th, etc) should work. The oldest method I know of for setting the after-length is to simply make the after length equal to 1/6th of the playing string length. A very logical argument could be made for that method because this places the bridge at 1/7th the total length of the string. By being there it cancels out the 7th harmonic of the (total) string. This is good because the
7th harmonic is false. That is what I use most of the time although I don't measure it all that closely. FWIW, Pianos are made so the hammer hits on the 7th harmonic to deaden it.
If you are able to accept the concepts of A0-B0 matching (which I will NOT discuss here), the best way to tune the after-length is to not tune it, but rather tune the entire vibrating assembly as a unit. By this I mean the tailpiece wire length above the nut, the tailpiece and the string after-length as a unit. Each part affects the resonance frequency of the whole. Several excellent papers have been published in violin acoustics journals that say the ideal is to have the tailpiece tuned to 1/2 the frequency of the body cavity resonance frequency (which usually turns out to be in the 25 to 40Hz range). This job can be somewhat difficult since you have to add or remove weight to or from the tailpiece while it is still on the bass. I've only done this while performing the complete A0-B0 matching process, therefor I have no personal knowledge of just how well tailpiece-A0 matching works by itself.