In a message dated 4/30/2005 6:11:26 AM Pacific Daylight Time, [EMAIL PROTECTED] writes:
> Maybe... As a research engineer I would like to see more data on the > difference > the prep makes versus the actual cryo process. The prep includes a thorough > cleaning and fixing any loose braces. That alone will improve many horns. > > >From my experience with old horns, a very high percentage of perceptible playing problems are related to leaks, of one form or another. Leaks can be very subtle, and a tiny leak can amplify another small problem out of proportion. Once you have a tube connected at the mouthpiece and a plug in the bell, there is no excuse for not learning how to blow bubbles in a bathtub or sink. It may seem complicated in theory, but seeing the bubbles is self explanatory. The horn will leak in proportion to the pressure you blow into it, and you can easily see what the leakage path is. Take the valve caps off so you can see how much pressure it takes to get air lleaking out the bearing ends. Tuning slides that aren't well mated often leak a little. Once you get started, the facination and figuring out the significance is a satisfying exercise. If you locate a leak that may be significant, black electrical tape is often sufficient to open and close it while to check the effect on playability. With the valve covers off, see if pushing the rotor to the bottom of the casing slows the leak. That would indicate a need for taking out end play. My experience with loose valves is they will often seal until something disrupts the oil/water emulsion on the sealing surface, or the distance between the sealing surfaces exceeds the limit for the specific lubricant. Just tightening the bearings radially is apt to constrain the rotor well enough that the sealable gap is not exceeded. It also keeps the rotors from wearing the casing elliptically. Very important if they aren't tapered to be self centering. Take your horn to a hardware store and work with the salesman to figure out how to easily set up a horn for testing. If you do this as part of your regular cleaning, you'll get to know the normal patterns for your own horn. If you can't find a suitable pipe stopper, a water baloon filled with flour works well. Spend a little time and thought putting the system together, so you get in the habit of doing it as a regular routine. I hope some listers actually do this so we can get a string going on what they observe. _______________________________________________ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
