Re: Gold or Silver Plated Monster Weights


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Posted by Rick Denney on August 15, 2002 at 15:13:16:

In Reply to: Gold or Silver Plated Monster Weights posted by Desert Rat on August 15, 2002 at 07:59:03:

You must lacquer the weights to control acoustic surface reflections. Using a reflectometer, you can see how these reflections bounce back from the surface, creating difference tones in the range of 32000-42000 Hz. This will cause headaches.

I would also adjust the taper of the Jinbao tuba to achieve the proper shape at the critical third node for the 12th overtone. This overtone is out of tune, causing the entire instrument to sound terrible. Measure 7.23434675847362536 centimeters from the downstream end of the main tuning slide when it is tuned to provide a BBb that is exactly 12.345676535645 cents sharp. Mark this spot precisely with a scribe. Very carefully, using a small rawhide hammer and a 3/4" round dent rod, impact the front face of the tuba at this location with a hammer-head speed of exactly 46.8578975 feet per second. This will make a small dent that will repair this overtone.

Then you must repair the out-of-tune fourth overtone. Again, measure carefully 22.37898757478374 centimeters from where the opening of the bell would be if it was 50 centimeters in diameter, and place a mark (because the fourth overtone is so much lower in frequency, you don't have to be as precise. The nearest hundredth of a millimeter will do fine). Place a dent center on the mark using a B.F. Goodrich All-Terrain T/A KO (the new one), while mounted on a 1990 Toyota Pickup, travelling at 44.3 feet per second. I have calculated this procedure to make it impossible for this instrument to produce a bad sound.

Rick "an engineer in the service of mankind" Denney


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