Compression?

Discussion in 'Trumpet Discussion' started by 9horn, Jan 28, 2010.

  1. 9horn

    9horn Pianissimo User

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    A question for the technicians of the bunch. Just how does having a good compression sound? Does it just make a difference when you kick the slides for note changing or does it affect your playing sound all around? I've come across some vintage, well broken in horns with poor compression that still play o.k. Thanks
     
  2. s.coomer

    s.coomer Forte User

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    A horn with good compression can not leak air around the valves.
     
  3. Markie

    Markie Forte User

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    what coomer said.
     
  4. 9horn

    9horn Pianissimo User

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    Thanks, but I guess I didn't get the answer:dontknow: ????????
     
  5. veery715

    veery715 Utimate User

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    At best, poor compression will affect slotting, blow, and intonation. This might make the horn more appealing for jazz, as loose slots are desireable and an airy sound is somewhat common in that milieu.

    If the compression is really bad, the horn might still be playable, but the effort involved would make it quite unpleasant.

    Using Hetmans #3 in a horn with poor compression will tell you a lot about how it might play if the valves are rebuilt.

    Remember that other faults in the horn such as leaky water key corks or loose slides or small leaks can also give symptoms which seem like poor compression.

    v
     
  6. Vulgano Brother

    Vulgano Brother Moderator Staff Member

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    Third, maybe fourth hand info (from a french horn player, no less!), but one famous repair tech said that at the customer's request he fixed the compression on some vintage old french horns (slides and valves) and they played much worse than before. He speculated that they were sort of designed with poor compression in mind and would still play fine.

    If you do decide to have valves and slides fixed, see if you can find what the original tolerances were when they were built. (I have no idea how, but it would be kinda fun!)

    Good luck!
     
  7. 9horn

    9horn Pianissimo User

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    Thanks V, now that's understandable!
     
  8. 9horn

    9horn Pianissimo User

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    Food for thought, good point.:think:
     
  9. veery715

    veery715 Utimate User

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    A quote from:
    Practical Physics for Trumpeters and Teachers
    by Renold O. Schilke
    (courtesy dallasmusic.org/index)


    Leaks also disturb the nodal pattern and affect intonation. Valves can be kept airtight by holding the tolerance on the pistons under .001 (.0005 inch on each side of the piston). This permits free movement of the valves and still gives good acoustical qualities. But regardless of the condition of the instrument, some players seem to be able to adjust and play beautifully. For example, when Rafael Mendez became associated with Olds, he asked them to build a new instrument that would be equal to the old Besson he had played for years. They tried everything they knew to please him, but they could not succeed. Finally one of the workmen took the valves out of the Besson, measured them, and found a surprisingly large clearance of over .008 Inch (the result of years of wear). He then made an instrument with similarly loose valves and Mendez was thrilled with the result. He was again performing on a totally inadequate instrument, but he was happy. He had overcome the problems caused by the leaky valves throughout years of practice (nobody ever practiced harder than Mendez), and for him it was just right.


    v
     
  10. ComeBackKid

    ComeBackKid Fortissimo User

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    Of all of my trumpets (nearly 50 now) only one has valves so bad that I cannot adjust for the leakage. My standard "quick test" is to remove the first valve slide, put my thumb over the outlet pipe, press the first valve and blow into the leadpipe (that method routes the air through all 3 valves but blocks the outlet creating internal pressure). Some are so tight that there is almost no sense of the air leaking out. Some have a slow leak (I generally consider that if half of my mouth volume leaks out in 10 seconds, the compression is marginal). But only one feels like I am blowing through a soda straw. I can still play it but it has a very airy sound across the range. The problem is that someone polished the pistons to apparently relieve a sticking problem and now the pistons almost 'rattle' in the casings they are so loose. So, the valves have to be really bad before the horn becomes useless in a normal playing situation.
     

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