Horn Temperature and tuning

Discussion in 'Trumpet Discussion' started by SmoothOperator, Feb 9, 2011.

  1. tobylou8

    tobylou8 Utimate User

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    It's the aluminum! :lol: It dissipates heat quickly!
     
  2. turtlejimmy

    turtlejimmy Utimate User

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    I'm not a metallurgist .... but something is different here.:lol:

    Turtle
     
  3. SmoothOperator

    SmoothOperator Mezzo Forte User

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    I am familiar with this problem, evidently flutes have to deal with it. Especially the solid silver ones.

    The solid silver is a selling point, because it comes up to temperature so fast, just by blowing through the flute once.

    I noticed this with my new horn a European silver plated cornet, compared to the Olds lacquer finished. A guess is that the lacquer prevents the horn from changing temperature as much or as quickly. Also maybe the longer tubing has something to do with it.
     
  4. turtlejimmy

    turtlejimmy Utimate User

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    Maybe the reason the Severinsen warms up so fast is its light weight. I wonder if the plating would have any effect. Any flute can be warmed up with just one blow if you close all the pads and cover the end by holding it against your leg.

    Turtle
     
  5. trickg

    trickg Utimate User

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    I would tend to think that it would have more to do with the overall mass of the instrument than any insulating qualities the lacquer would provide. In fact, if lacquer does insulate, it would make sense that it would warm up more quickly because the inside tubing of the horn is not lacquered on either a silver plated or lacquered instrument.

    The effect of temperature on intonation isn't anything new - it might be new to you or something you just recently realized, but to me it's just an ears thing. As a former Army Bandsman who has played outdoors in temps ranging nearly 100 degrees (probably did a couple of funerals in minus 0 temps, and I know I've marched parades at 100+ degrees) it's just one of those things you learn to deal with, mostly with your ears and making judicious tuning slide adjustments when you can.

    My second summer as an Army Bandsman, summer of 1991, was just blistering and at times we'd do ceremonies where my trumpet actually became hot to the touch - just miserable. Aside from being uncomfortable, intonation went right out the window because of the variance of instrument sizes and materials, so we dealt with it the best we could, but we knew going into it that outdoor ceremonies on hot days were going to be rough from an intonation perspective.
     
  6. gmonady

    gmonady Utimate User

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    Our friends from Wikipedia give the following explanation:
    Thermal expansion - Wikipedia, the free encyclopedia

    Linear thermal expansion coefficient relates the change in a material's linear dimensions to a change in temperature. It is the fractional change in length per degree of temperature change:

    Coefficient of Expansion = 1/L dL/dT

    where L is the linear dimension (e.g. length) and dL / dT is the rate of change of that linear dimension per unit change in temperature.

    What this says in words is that the effect of temperature on length over time is inverslational proportional to the length of the tubing. Each metal allow that is made for the trumpet will have a different coefficient of expansion, and for those of us that have mixed allow like the Old recording that has more copper in the bell section, will have the horn expand in different places at different rates.

    So as they say in the math world: QED.
     
  7. rowuk

    rowuk Moderator Staff Member

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    Lacquer and silver plate have nothing to do with it. Solid silver flutes don't work that way either. Remember - if they can warm up that fast - the outside air would cool them down equally fast!

    Horns that warm up faster are lighter in weight (perhaps smaller in bore too) and therefore have less "cold" stored that needs to warm up.

    The density of the air is the BIG issue as the sound we hear has not passed through the horn once, rather as a standing wave in the instrument several times. The tone coming out of the bell is only a bit of "leakage" of this standing wave due to imperfections compared to a perfect resonator with no leakage or a perfect horn with a suboptimal resonant behaviour.
     
  8. SteveRicks

    SteveRicks Fortissimo User

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    Rowuk is on target. Mass of the horn would be the biggest factor in how fast a horn warms up.
     
  9. gmonady

    gmonady Utimate User

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    From the physics equations I find related to the coefficients of expansion of metals, mass is not a part of the equation for lenthing the horn. It would be this value that would relate to changing tone and pitch quality. Here, only the length an alloy characteristics of the metal impact on expansion. For brass the coefficient is 19 x 10(-6) cm/oC.

    Heat (lost or gained) by the metal (Q) is indeed mass dependent and is found by:
    Q = m C ΔT
    Where m is mass, C the the specific heat value for the metal, and T the temperature.

    So the weight of the instrument will determine how rapidly it warms. As other individuals in this thread have identified that the pitch of the note is most influenced by the temperature of the air passing through the system of tubes. So from my understanding of the physics of the entire process, any effect on warming air impacted by the temperature of the metal, will be indeed be dependent on the mass of the horn.
     
    Last edited: Feb 12, 2011
  10. tpsiebs

    tpsiebs Piano User

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    The differential in size from the relative expansion/contraction of the METAL is insignificant compared to the density of the air inside the instrument as it is affected by hot/cold fluctations.
     

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