What does heavier valve caps do ?

Discussion in 'Trumpet Discussion' started by Laursen, Feb 18, 2010.

  1. Markie

    Markie Forte User

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    Some will tell you the effect of heavy caps its nonexistant.
    I can use either. I choose to use the heavy caps as it seems to make things a little more stable and I like the subtile difference in sound.
     
  2. guyclark

    guyclark Piano User

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    Right on, brother Rowuk!:thumbsup:

    I expected a lot more disagreement with my contentions! Maybe we're not all such gullible sheep as I originally thought! :roll:

    Guy Clark
     
  3. guyclark

    guyclark Piano User

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    Of course, this is the truth of it. If it (heavy valve caps, stripping the lacquer, freezing your horn in liquid nitrogen, whatever...) makes you feel better about your playing, you'll play better. Even a placebo sometimes seems to work!

    I'm too much of a skeptic and scientist for these things to work for me, he says, proudly, not noticing what snake oil I've swallowed, too! ROFL

    Guy
     
  4. gzent

    gzent Fortissimo User

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    Sorry, Guy, but not only does the physics add up, I've actually done a lot of experimenting while building various trumpets that confirms the theory (along with what I've observed from a master builder, Jason Harrelson).

    By making a wall of Brass thicker you increase its acoustical impedance and when that happens the wall more efficient reflects the wave. If a brass pipe reflects more of the wave that means it is vibrating less in response to the standing wave within it and more of the acoustic energy reaches the end of the wave guide.

    Do a search on "acoustic impedance of materials" and you will see what I am trying to describe.

    Greg
     
  5. rowuk

    rowuk Moderator Staff Member

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    A trumpet is a complex combination of mass damping and coupling, this allows vibrations to "pass through" the metal and give the player feedback. Adding weight "damps" vibration. On the valves this will not substantially change anything that the audience hears, it will change the feedback to the player somewhat and this is what some perceive to be the improvement. If they would check the tuning, they would discover that on horns not designed heavy, that the intonation is influenced in a negative way (the 4th space E and Eb as well as the 4th line D get flatter and the G on top of the staff gets sharper).

    I insist if you add weight to the valves, you must also add weight to the bracing and change the way that the bell is damped. Then the player will have less feedback, but the audience will get more. Some of the flexibility of the original design is gone.

    I have been doing extensive studies on bracing and quite a few interesting things have come up. I have discovered that coupling instead of damping can improve the response of a horn without hurting other things like adding weight does. My C trumpet is being modified and I will report when I get it back. The first tests showed much better intonation.

    For the record: the resonant frequency of the horn is based on the volume of air in the horn, not the mass. Adding weight does not lower the resonance. It changes how much energy leaks through the metal. More damping means less energy gets to the player. More damped horns are harder to play when the room does not have good acoustics.
     
  6. gzent

    gzent Fortissimo User

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    Are you using damping to mean acoustic impedance?
    If so, then yes, more energy goes past the horn and less gets to the player.

    I know my Bravura has much higher acoustic impedance, hence, greater efficiency than
    typical horns and is much easier for me to play than any other "normal" weight horn I have tried. So, no, more efficiency doesn't make a horn harder to play, IMO, it makes it a whole lot easier.
     
  7. guyclark

    guyclark Piano User

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    Hi, Rowuk!

    I don't know if I agree with the first statement in my quote above. I haven't any real data.

    I was refering to the resonant frequency (if there is one) for the trumpet as a whole, not the air column inside that actually makes the sound. Clearly, if the body of the horn is vibrating, that vibration will modulate the air column vibration and cause some change (coloration?) to the resulting sound. I simply considered the body of the horn as a mass vibrating in the player's hands as a spring and weight system. Increasing the mass in such a system clearly reduces the resonant frequency of that system.

    In reality, I believe that various parts of the horn will vibrate in different ways, that may or may not interact with one another. A heavily braced horn, like a Monette Raja or some such should minimize that body vibration, leading to less modulation of the air column, and possibly a "purer" tone. I don't know if it really works like that though...

    Guy

    Guy
     
  8. gzent

    gzent Fortissimo User

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    Again, here's some technical paperwork on how trumpets work:

    Trumpet Physics

    Of particular note is the experimental results of Schilke, which clearly supports the acoustical impedance model.
     
  9. guyclark

    guyclark Piano User

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    I'm not sure I'd agree with the quote above, either, and I certainly don't agree with what you said intially:

    >>By making a wall of Brass thicker you increase its acoustical impedance and when that happens the wall more efficient reflects the wave. If a brass pipe reflects more of the wave that means it is vibrating less in response to the standing wave within it and more of the acoustic energy reaches the end of the wave guide.<<

    The big impedance changes occur at each end of the horn, the buzzing lips, and the bell. The acoustic standing wave has nodes at these two points and energy leaks mostly from the bell end, producing the sound, while some leaks back into the mouth which we feel. The impedance of the tubing itself to the air column really has no bearing on the situation as any resonance across the tubing is of such high frequency as to be inaudible by humans, anyway!

    Think of how a gas or ruby laser works: light energy (photons) introduced stimulates the lasing material to emit more photons, some of which race along the body of the laser, only to be reflected back along the body, stimulating the emission of yet more photons. The light bounces back and forth in a positive feedback system, until the maximum number of ions in the lasing material are emitting photons. Some of this energy leaks out the one end with a special "leaky" mirror. This is analagous to the bell of our brass instrument. The tubing containing the gas mixture in a gas laser has virtually no effect on the overall operation of the laser, save to contain the gas. The tubing of the trumpet has no other purpose other than to contain the vibrating air column.

    YES, the trumpet isn't perfect, (even if some of us players are ROFL)and some of the vibrating air column's energy IS transferred to the tubing. That said, much of it, if not most of it is dampened by the hands holding the trumpet, and is never heard. Some of it does remodulate the air column causing some small effect to the otherwise "pure" tone that could be produced otherwise. It's my contention that this is of such small effect as to be virtually inaudible, AND, the contribution of the valve casings to this vibration is SO small as to be ignored.

    I concede that the Monette and Harrelson methods of extreme bracing MIGHT have an audible effect on the sound... it's pretty hard to test, though, and as a scientist/engineer, I have a hard time believing extraordinary claims without extraordinary proof. It's a character flaw, I know!:-P However, the valve caps.... sorry I don't believe it!

    As I said before, if it makes you think you'll play better, you likely WILL play better, and I shouldn't be telling you otherwise. I just don't like the idea of sharp salesmen selling us the Emperor's new clothes, if you know what I mean! :evil:

    Later!!

    Guy
     
  10. gzent

    gzent Fortissimo User

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    Yeah, I thought it was all BS too, until I actually went to Jason's shop and played his horns back to back with my own and several other big name horns he had there on trade or being modified.

    Its not hard to test at all and its not the Emporer's new clothes. Its applied physics.

    And if you have never played an efficient trumpet like a Harrelson or a heavy Monette, and have never
    done any trumpet modifications yourself you will never know what you are claiming doesn't exist.
     
    Last edited: Feb 18, 2010

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