Dual Key Trumpets....

Discussion in 'Trumpet Discussion' started by BrassBandMajor, Jul 15, 2017.

  1. trumpetsplus

    trumpetsplus Fortissimo User

    Jun 11, 2006
    South Salem, NY
    I have an ascending C/D trumpet that plays pretty darn well in tune. Yes there are some notes/fingerings that have issues, but these are predictable, and the overall result is very positive.
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  2. OldSchoolEuph

    OldSchoolEuph Mezzo Forte User

    Apr 1, 2011
    Read what Rowuk posted carefully. Notice he said "work", not "have perfect intonation". He then points out approaches that work best, multiple leadpipes, interchangeable bells. This returns to the architectural issues discussed here. At the end of the day, remember that your straight Bb does not have perfect intonation - for every model there are quirks. When you adapt to more than one key, those quirks increase cumulatively. Dual key horns must optimize compromises between optimized compromises

    remarkably, the best do manage to achieve a result less quirky than the net and when 1+1 is less than 2 it is impressive, but still less intonationally solid than 1.
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  3. Vivek Patel

    Vivek Patel Pianissimo User

    Jul 8, 2017
    Porterville, CA
    Correct me if I'm wrong, but the notes on a single key trumpet are in tune because the lengths of each slide section are proportional to the length of the horn when none of its valves are depressed. The lowest pitch produced by the open horn with none of its valves depressed is the fundamental, and is the key of the trumpet. The lengths of the first, second and third slides of a Bb trumpet are designed to lower the pitch of the open horn (which resonates at a Bb) by a major second, a minor second, and a minor third, respectively. But it is the ratio of the slides' lengths to the open horn, rather than absolute slide lengths, that allows for these specific pitch changes (major second, minor second, minor third).

    If the length of the leadpipe was the only factor, and the slide lengths for a Bb trumpet magically worked for all cases, one could very easily design a tuba with a trumpet valve block! Imagine that, a tuba with tiny trumpet slides! ROFL
    Last edited: Jul 16, 2017
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  4. Dale Proctor

    Dale Proctor Utimate User

    Jul 20, 2006
    Heart of Dixie
    I had a nice Bach C trumpet before I owned a good Bb trumpet. Thinking I'd save a lot of money, I bought a Bach slide set to convert the C to a Bb. It came with all 3 valve slides and a longer tuning slide, all calibrated to work with the 25C mouthpipe that was on the horn. Yeah, it worked pretty well, but the alternate fingerings required on the C were also needed on the Bb conversion, and the horn was a bit squirrley overall. I ended up buying a good Bb horn and selling the slides.

    Last edited: Jul 17, 2017
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  5. OldSchoolEuph

    OldSchoolEuph Mezzo Forte User

    Apr 1, 2011
    Yes, but no. For one partial, the mechanics of this can perhaps be perfect - at least as far as each individual valve, less so for combinations. But complicating this is that the horn must play in many partials above the fundamental. As you go up in frequency, the physical to frequency relationships are not perfectly symmetric (owing to both the nature of how our musical system works, and the physics of the overtone series which does not base partials on doublings but rather the natural system of octave, fifth, octave, third, fifth, seventh, octave . . . .) as the partials get smaller the way in which the proportions of the horn interact with the frequency produced shifts. In reality, the proportions built are not particularly correct for the fundamental (because no one plays down there) and are adjusted as a compromise that favors the best intonation across the "useful range" of the horn - whatever the designer decides that is. After that, you have to consider bends, bumps, braces & expansion and how the geometry of the air column at given "nodal points" for each frequency (and this is not a singular relationship, it is an interaction of multiple points for any pitch) influences the final frequency of the resonating column behind the reflection point at the bell - the horn being a half-wave instrument also adding to the mathematical challenges.

    And then there is the issue of what key you are playing in when in an ensemble given that intonation is relative to the harmonic structure . . . . I sometimes change fingerings for certain notes depending on key - another quirk of our musical system.

    Thinking about these things is enough to make to make a brass guy want to take up building xylophones!
    Last edited: Jul 17, 2017
  6. veery715

    veery715 Utimate User

    Mar 6, 2007
    Ithaca NY
    A trumpet or cornet in 1 key is already a compromise and needs either lip or slide adjustment to play in tune for some notes. Add the ability to lengthen the instrument to a lower key with a longer slide or set of slides and you just expanded the compromise at least doubly.

    Read up on the physics of music and the subject of the tempered scale and you will see that, while math determines much of what makes (Western) music work, there are compromises being made everywhere you look, er, listen.
    Last edited: Jul 17, 2017
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  7. rowuk

    rowuk Moderator Staff Member

    Jun 18, 2006
    The proportions change. The ratio of cylindrical to tapered, the proportion of length before and after the bell, distribution of mass. There is so much more to a trumpet than length... Even a natural trumpet with no valves changes in the intonation of the partials depending on the tuning bits, mass, tension, material thickness, ... I think the most critical part for intonation is the mouthpiece and leadpipe. Slotting is mass distribution and color is bracing and bell.Of course all factors are interrelated, but that would be my experience in basic traits. If we have dodgy intonation, hard slotting is a disadvantage.
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  8. LaTrompeta

    LaTrompeta Forte User

    May 3, 2015
    Colorado Springs
    At best, it's a compromise. One side is designed to be in tune.
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  9. scottfsmith

    scottfsmith Pianissimo User

    Jul 2, 2014
    Its interesting how over time the range of pitch adjustment has gradually narrowed. Cornets started out with a vast array of shanks down to F as the standard, following horns of the period, but by the end of the 19th century only Bb/A was common. Early trumpets took off from where the cornets were at the time -- Bb/A was very common on early trumpets, see the pictures in Franquin's Method for example, and was common up until the 20's at which point they started to fade. This evolution makes sense, as the instrument was refined there was less tolerance for quirks in the design.

    I have a few Bb/A instruments and while I don't play in A much they seem to do OK. My one Bb/C trumpet is a C trumpet with Bb glued on the side - get ready to lip!
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  10. BrassBandMajor

    BrassBandMajor Fortissimo User

    Jan 13, 2015
    What do you mean by Bb glued on the side?

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