how much to cut off the 3rd valve slide

Discussion in 'Trumpet Repair and Modification' started by mike ansberry, Oct 8, 2018.

  1. mike ansberry

    mike ansberry Forte User

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    I play a 1933 Conn 409b on rock gigs. It has the 3rd valve trigger and no 1st valve trigger. I have turned the upper slide around on the 1st valve and made it a trigger mechanism. The 3rd slide is a bit too long and makes the Ab and Eb too flat.

    Any ideas about how much I should cut off the 3rd slide?
     
  2. N1684T

    N1684T Mezzo Forte User

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    Is this a trick question?
     
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  3. rowuk

    rowuk Moderator Staff Member

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    Measure the horns that you have that work properly and compare.
     
  4. Vulgano Brother

    Vulgano Brother Moderator Staff Member

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    I like the third valve length to equal the 1,2 combination at proper length. Might even have to pull a bit for Eb and Ab.
     
  5. trumpetsplus

    trumpetsplus Fortissimo User

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    Easiest approximation is:
    Pull the slide out to double the number of cents flat. That distance is close to what you will need trim off the slide. It is not exact because proportion increase distance is not equal to proportion decrease distance, but it will be pretty close.
     
  6. SteveRicks

    SteveRicks Fortissimo User

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    Okay, I am lost. Why would Conn have made a horn where the 3rd slide is too long? Has this something to do with the change you made to the 1st slide?
     
  7. trumpetsplus

    trumpetsplus Fortissimo User

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    Because slide lengths have always been something of a crap shoot
    https://asa.scitation.org/doi/abs/10.1121/1.1937167
     
  8. Vulgano Brother

    Vulgano Brother Moderator Staff Member

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    I'd prefer mine to be 0 cents flat, and use the first and third valve slides to tune.
     
  9. Dale Proctor

    Dale Proctor Utimate User

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    On older Conns, the prevailing opinion is the 3rd slide was made a bit longer as a compromise for the sharp low D and C#. That made them close enough to lip those notes into tune, since many instruments had no way to manipulate the 3rd valve slide on the fly.
     
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  10. trumpetsplus

    trumpetsplus Fortissimo User

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    Correct.
     
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