What determines a trumpet's key?

Discussion in 'Trumpet Discussion' started by hoserb, Jan 6, 2012.

  1. hoserb

    hoserb New Friend

    Sep 10, 2008
    Hello. Never really gave this a thought until purchasing a pocket trumpet and noticed the options...

    I assume that a horn's key ( B-flat, B, etc.) is determined by tube length. However, what is used as a benchmark tuning source?
    Playing "B-flat" on my piano equates to a "C" on my B-flat horn. If I had a "C" horn, what's the equation?

    What's the reason (advantage?) of different keys? Ease in playing a piece in a difficult key signature?

    Thank you-
  2. codyb226

    codyb226 Banned

    Mar 9, 2011
    Florida, US
    Yes, the length of tubing. If you play C on the trumpet it is a Bb on a piano, G on a trumpet is a F on a piano. I may not be correct on this, but the advantages is for playing in certain keys.

    Welcome to TM hoserb.
  3. BrassEye

    BrassEye Pianissimo User

    Sep 9, 2011
    The length of the tubing determines the pitch. On a Bb trumpet the trumpet's C is the same pitch as the piano's Bb, assuming both are tuned to A=440. A C trumpet's C is the same pitch as the piano's C. An Eb trumpet's C is the same pitch as the piano's Eb.

    Prior to the invention of the chromatic trumpet, the instrument was restricted to the notes available in the harmonic series (much like not being allowed to use the valves on a modern chromatic trumpet). Trumpets of different lengths were therefore required to play in different keys. When you use a valve or valves on a modern instrument you are effectively "picking up" a longer instrument as you are adding to the overall length of tubing, allowing you to access notes unavailable in the harmonic series as it is without any valves depressed, or allowing you to play available notes more in tune (think of the Bb above the staff; it CAN be played open, but it's not in tune, hence most will play it with 1st valve).

    Use of different pitch instruments today can be for a number of reasons; a change in timbre, ease of transposition, ease of fingering, or security in the higher register being perhaps the main ones.
    tobylou8 likes this.
  4. hoserb

    hoserb New Friend

    Sep 10, 2008
    Hello and thank you for the responses and information...
  5. rowuk

    rowuk Moderator Staff Member

    Jun 18, 2006

    345m/s= Speed of sound
    466Hz is Bb (see link below)


    That wavelength (λ) is the pedal tone. You may notice the discrepancy of an octave here. The reason is that a trumpet with its lip reed belongs the the "gedackt" family of instruments and sounds an octave lower. That means only 1/2 wavelength fits in the horn. For the trumpet, the formula looks like this:



    with the example above, the piccolo trumpet in Bb is only 37" long but has a pedal tone of 233 Hz. A flute would have to be twice as long to play the same pedal note. Ever notice in band that the trumpet and clarinets play the same range, but the trumpets are roughly twice as long?

    Frequencies of Musical Notes
    Brass instrument (lip reed) acoustics: an introduction
    Gedackt - Wikipedia, the free encyclopedia

    Please note that the acoustic length of the trumpet is different than the physical length. That is what the horn shaped bell (and tapered leadpipe) is for. It helps us play the usable notes better in tune.
  6. trumpetsplus

    trumpetsplus Fortissimo User

    Jun 11, 2006
    South Salem, NY
    The effective length of a regular Bb trumpet is approximately 56.6", C trumpet 50.4", D trumpet 44.9", Eb trumpet 42.4" and the piccolo Bb 28.3".
  7. shakey

    shakey New Friend

    Feb 18, 2012
    I know this thread's a little in the past, but I have a follow up question or questions. First what is the feasability or quality for someone interested in a nice easy playing trumpet (on a budget of @ $400) in getting a trumpet that's interchangeable from Bb to C. Also, I am used to playing a Bb trumpet. Would the fingering for the transposed notes in C be the same as in Bb? I am interested mainly in a nice looking easy playing trumpet, but if the fingering is the same and there is no sacrifice in playability and quality, I might be interested in going that route.

  8. richtom

    richtom Forte User

    Dec 7, 2003
    When you find a good interchangeable Bb/C horn, for $400, please let us all know. Hate to say it, but you will never find one.
    No, the transposed fingering is not the same. If you have a Bb trumpet part in front of you and you see a 2nd space A, you will play it open on a C trumpet. If you see a 1st space F, you play it 2&3. Bb parts played on a C are transposed down a full step.
  9. Ed Lee

    Ed Lee Utimate User

    Aug 16, 2009
    Jackson NC
    And don't forget to remove two sharps from the Bb music.
  10. Phil986

    Phil986 Forte User

    Nov 16, 2009
    Near Portland, OR.
    I have a Yamaha 4420E, which came with 2 complete sets of slides, one for Bb and one for C. It is in tune for both lengths, probably because it's like having 2 different instruments with only the leadpipe, valve block, bell and bracing in common. The bracing part certainly is the most tricky but the good people at Yamaha seem to have solved that problem when they conceived that horn. It is great and I would not part with it for anything.

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