Hi Paul. You took the words right out of my mouth. I would (if I might be presumtuous) add three points to your fine and comprehensive piece:
1. Another sign of leakage is the drop in pitch of the Bb horn in relation to the F. This is caused by the fact that the Bb horn wears out faster. 2. The so called "pop test" is pretty much useless for evaluating valve tightness. It relys on several misconceptions, eg., that the sides of the rotor and casing are straight and concentric and seal equally in all directions. All the pop tells you is the relative tightness of an air circuit that is never used. The only accurate test is one using a static air pressure gage to measure the leakage in the actual air path. 3. Assuming the bearing plate is seated all the way down and we're talking about end play of less than .010" or so (that's really a lot), the ability of the rotor to move vertically is not a significant cause of leakage and removing the end-pay will not tighten the air seal to any noticable extent. I think the most important thing to remember about valve tightness is that, assuming the valves were tight when new, the primary cause of deterioration is not mechanical but chemical, and is almost entirely preventable. Valve that have been oiled on a regular basis have a service life of twenty years or more. Bob Osmun -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Saturday, January 07, 2006 11:26 AM To: [email protected] Subject: Re: [Hornlist] Signs of leaky valves? In a message dated 1/6/06 5:22:51 PM, [EMAIL PROTECTED] writes: > >From the player's viewpoint, what are the signs and symptoms > >suggestive of > valves that are leaking? Are there some tests that can be done at home > to confirm one's suspicions prior to taking the horn to a repair > technician-artist? > > Thanks, > Linda > > My last post had a mistake in the typing. here it is corrected. sorry for that. Hello Linda, >From the players viewpoint valve leakage can cause the upper harmonics >to go flat, difficulties with intonation, difficulties with clean articulation, and an indistinct feeling as to where the centers of the notes are. The sound also loses resonance and becomes unclear as the valves lose compression and begin to leak The general feeling is that you are having to overwork to get good efficent results. The danger is that as the leakage develops over a perion of time, the player unconciously adjusts to it without being aware of why they are having to work harder, and bad habits can develop. It is always important to take good care of your valves to avoid unnecessary wear. One fast way to initially check for valve leakage is to (making sure that your slides are well greased before you do this) pull a slide out about 1 1/2 inches and the push it back in. Immediately push down the appropriate valve lever. You should hear a distinct "pop" when you depress the valve. This type of test is basically a superficial test and is not totally reliable as a diagnostic tool, but will give you a first impression as to whether your valves are leaking. Now you can begin with more serious testing. The first thing to check when testing to see whether your valves leak, is to check for end play in the valve bearings. End play is movement that can occur both vertically and / or horizontally. Hold your valve by the rear bumper shaft and move it vertically back and forth to see if there is any play in the valve. End play will show up as movement- however slight. Check each valve individually and then repeat the process checking for horizontal movement. Again, check all of the valves. If there is movement either way, this could indicate that the bearings are worn. Or that the bearing top plates are not seated correctly. Check the top bearing plates and if they are not seated flush with the valve casing, carefully tap them down so they are flush with the casings, then check for movement once the plates are correctly seated. Bearing play will cause valve leakage, but does not necessarily mean that the valves need to be replated. It can just mean that the bearings are worn and need to be tightened. Or that there is corrosion in the valves. The next step in checking your valves is to buy some heavy woodwind key oil. I have found that Buffet key oil is best. Some manufactures package valve oil as key oil and this is too thin for our next procedure. Once you have warmed up, find a quiet place and play some passages on your horn that are tricky. Examples of good passages to play are: For high register: Ravel Piano Concerto solo Bruckner 4th opening Mozart G minor symphony Beethoven 7th Symphony Beethoven 6th solos These passages are more difficult to play if you have valve leakage because the leakage causes the overtones to be flat and the player experiences this as the notes being harder to play and more uncertain as to obtaining a nice free, resonant entrance. This generally tends to make the player use too much effort in production. Then try a few low register passages such as: Beethoven Fidelio 2nd horn both the horn 5ths and the solo Mussorgsky pictures - the first solo for 1st horn Wagner- 8th horn opening to Rheingold These passages are more difficult to play if you have valve leakage because the pitch centers are indistinct, articulation is difficult, and intonation is poor. Once again, this can lead the player to over control in their attempt to perform the passages correctly. When you are playing these passages pay close attention to the amount of work it takes to play them. Pay careful attention to the intonation and whether or not the notes feel centered and that the tone is resonant. Immediately after you have done this, put some of the woodwind key oil directly into the valves (4or 5 drops into each slide tube though the outer slide tubes). Make sure that you put it into all of the valves. The purpose of this it to use the heavy oil to artificially tighten up the valves to remove any leakage. This heavy oil will most likely make your valves slower-hopefully anyway. If your valves do not slow down with the heavy oil in them, then there is a good likelihood that there is valve wear. Now replay all of the passages in the same order and as similar to how you played them the first time and see if you notice a difference in how your horn responds. Is the sound clearer and more resonant? Do the notes feel more centered? Is the intonation better? Is the articulation easier? Is it less work to play these passages? Is it easier to play soft? When you have finished with this experiment you will have to remove the heavy oil. Use some regular valve oil. I personally prefer Al Cass for this -- and put it into the valves the same way you put in the heavy oil. Keep some paper towels handy to clean up the mess as the heavy oil is thinned by the valve oil and starts to come out. Empty the oil from all of the slides and tubes on the horn. If you notice that the horn feels and sounds better with the heavy oil in the valves, there is a good chance that you need some valve work. Sometimes excessive corrosion can cause valve leakage because as the corrosion builds up on the rotors and in the casings, it rarely builds up evenly and the unevenness of the deposit causes spaces in which the valve leaks and the valve compression gets degraded. Valve cleaning is the necessary first step if you decide that your valves are leaking. Then you can tell how much leakage there is because corrosion will not be an issue. At this point you need someone qualified to help you determine if you need bearing work or valve plating. Most of my clients (our shop clientele is 95% professionals) choose valve plating only as a last resort. Valve replating can be well done and very poorly done and most often is somewhere in between, so it is important to choose wisely if and when you have your valves worked on. This information is sent as a basic guide only, to help you decide if your valves are leaky. Sorry for the length of it, but I hope it helps. Paul Navarro Custom Horn Lyric Opera of Chicago ( ret.) _______________________________________________ _______________________________________________ post: [email protected] unsubscribe or set options at http://music2.memphis.edu/mailman/options/horn/rosmun%40osmun.com _______________________________________________ post: [email protected] unsubscribe or set options at http://music2.memphis.edu/mailman/options/horn/archive%40jab.org
