Measurements of trumpet bore along entire length

Discussion in 'Trumpet Discussion' started by gordonfurr1, Jan 20, 2015.

  1. gordonfurr1

    gordonfurr1 Forte User

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    Imagine mine. I do this kind of thing all the time.
     
  2. Sethoflagos

    Sethoflagos Utimate User

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    There are several different types of tuned exhaust, but if we consider the principle of the two-stroke tuned exhaust there's an interesting parallel.

    The general idea is to use the reflected pressure wave to support the closure of the exhaust port.

    If the timing is too early, it can obstruct proper evacuation of burnt gases from the cylinder = STUFFINESS

    If the timing is too late, uncombusted gas can escape the cylinder through the exhaust port prior to ignition = LOSS OF COMPRESSION

    Get the timing right, and the engine breathes at maximum EFFICIENCY

    The parallel isn't particularly exact, but you can regard the return wave of a trumpet being correctly timed when it neither sucks when your aperture needs to close nor blows when your aperture needs to open. This in-phase support of the lip motion is critical as it gives the 'right sort' of free-blowing openness (ie the sort that doesn't suck your face off).
     
  3. rowuk

    rowuk Moderator Staff Member

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    By jove Watkins, he's got it!

    The difference between stuffy and free blowing is often just a matter of sympathetic vibration, allowed by relaxing.............
     
  4. Sethoflagos

    Sethoflagos Utimate User

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    Gordon,

    Since you seem to be a motor sports fan, here's another tenuous analogy that I'd appreciate your thoughts on.

    Flywheels.

    The idea behind a flywheel is to store a few cycles of the engines output in the form of a rotating mass that tends to oppose changes in crankshaft speed in the interests of smooth running. Too small a flywheel and the engine runs unevenly, is prone to stalling, especially at low revs and low throttle, and loses speed rapidly on inclines and bends. Too large a flywheel kills acceleration and requires heavy braking for cornering. Both extremes are bad for fuel consumption.

    I'm sure you know that sports engines tend to have small flywheels, sacrificing low end drivability for fast response, whereas a luxury sedan will tend to have a large flywheel for steady cruising at low revs for passenger comfort.

    Now think of the air column in your trumpet as a flywheel. Utilising acoustic reflection from beyond the bell, it too collects and stores a few cycles worth of energy, not in the form of a rotating mass as such but as a linearly pulsating volume of gas. And being a substantially larger body of energy than that entering and leaving the trumpet on each cycle it helps maintain sychronisation of sound output ('vehicle motion'), air column ('flywheel'), embouchure ('crankshaft/transmission') and airstream ('engine power output').

    Having said that, the 'flywheel' concept must also include the brass of the instrument, particularly the bell as this is also vibrating in synchrony with the rest of the system and with its own percentage of stored energy.

    How can this analogy help us to understand the performance of different instruments.

    Well the smallest 'flywheel' in my collection is the B&H Sovereign Studio, an instrument specifically designed for Derek Watkins' lead work. It's ML bore (0,459") with a paper thin, yellow brass bell, and at spot on 2 lb it's a good 4 oz lighter than even the Wild Thing and Severinsen, which until recently were the lightweights of my collection. It sounds a very 'loud' instrument to me because so much of the sound is coming out sideways and backwards through the bell wall. This 'loss' has to be made up somewhere, and to get much sound bouncing back from the far end of the room, you've to put a fair bit of air through it. As CornyAndy suggested in his review a few months back, it's certainly playable in the low register but there are some control issues be addressed. The payback (and it's a big payback) is the responsiveness, particularly up top. If you've a bunch of high lip trills to master, this is the tool for the job.

    At first I was very confused about why I found this instrument so very easy to play. I'm by no means the player I once was (and that's not saying so much!) and by any standards, this design is extreme. It should not be easy for a below-par player to take to this instrument. And then it dawned on me why Richard Smith might have designed this instrument with such strong slotting. It may be a lightweight flywheel that does not give your embouchure a lot of stabilising feedback, but the 'flywheel' is designed to lock strongly on to particular speeds. Hence while not providing much assistance to the embouchure, it compensates by reducing the demands put upon it. If this indeed the case, it's a really neat trick!

    On to heavier flywheels

    The Yamaha at 2lb 7oz is nearly 25% heavier than the Sovereign, and that's down simply to thicker tube wall rather than the flying buttresses and spider web flanges you see on a lot of heavyweight models. The same ML 0.459" so that component of the flywheel is the same. There are better people on this site for describing the playing characteristics of the Xenos so I'll just limit myself to saying that whatever the instrument lacks in responsiveness, it more than makes up for in superb stability of sound through the whole dynamic range. Big flywheel.

    So why how does the Wild Thing come have a big flywheel?

    Well it's a pretty complicated construction, some of which I haven't yet figured out. Some of the brass plate (eg slide inners) is extremely thin. Being LB (0.470") the 2lb 4oz of brass is more thinly spread to envelop the extra air volume.

    And that air volume figure is important. Not only is the Wild Thing a large bore instrument, the bell flare is much broader than most other trumpets. For interest I filled it with water, which I then measured at over 400 ml. By comparison, the Yamaha tops out at 350 ml. So while the bore diameter only varies by about 2.5%, the (approximated!) volume of the air column in the Wild Thing is about 15% greater. This has to make a difference.

    From day one I've regarded the Wild Thing as a bit schizophrenic. It's very loud to the performer, and brightens easily, like other lightweights. Yet it plays superbly in the lower register, and with excellent stability. In fact if I'm working on focusing my embouchure, I'm beginning to prefer the Wild Thing over the Yamaha, and I never thought I'd hear myself say that.

    My guess is that despite the somewhat lower efficiency, the extra breadth of the air column in the Wild Thing gives it extra strength in the 'spring' supporting the embouchure, without going the strong slotting route.

    So how much sound needs to be reflected back from the bell to produce an acceptable flywheel? I don't know. But it would be an interesting figure to find out. Gut feel tells me maybe 75-85%?

    Work in progress.
     
  5. tobylou8

    tobylou8 Utimate User

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    Could this be what you've seen before? The measurements are in a link midway down the page. Like Cornyandy, this makes my head hurt but know it's needed.

    Trumpet Schmumpet
     
  6. Vulgano Brother

    Vulgano Brother Moderator Staff Member

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  7. gordonfurr1

    gordonfurr1 Forte User

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    Nope. Not what I had before seen.
    Though it IS interesting, isn't it?
    What I had afore seen was a hand scribbled text listing bore diameter about every inch along the length of a trumpet...I think a vintage Olds model.
    Really, I seem to recall it was maybe the widths of the flat sheet of brass that would be cut in a flaring shape and then formed around a mandrel and soldered.


    Here's the link you shared:

    Cornets: Conical Cylindrical Total % Conical
    (most dates are estimates) total total Length
    Bach 37 (1940-present) 37.88 16.5 54.38 70
    Schilke A1 (1965-present) 37.55 16.5 54.05 70
    Connstellation 28A (1955-1965) 37 16.625 53.625 69
    King Master (1912-1965) 38.2 14.5 52.7 72
    Conn Victor (1912-1965) 33.6 19.25 52.85 65
    Blessing Artist (1945-present) 37.5 16.25 53.75 70
    Buescher 15 (1917) 30.15 22.75 52.9 57
    Holton New Prop/Clarke (1906-1936) 38.55 12.75 51.3 75
    ConnQueror (1900-1910) 34.85 17.5 52.35 67
    Conn Wonder (1886-1910) 39.1 12.75 51.85 75
    Besson Dessideratum (1880-1935) 34.75 16.5 51.25 68
    Besson Concertiste (1885-1960) 35 16.75 51.75 68
    Heald (low pitch) (1889-1925) 35.8 18 53.8 67
    Fiske Rotary (1866-1887) 34.75 18.25 53 66
    Conn & Dupont 4 in 1 (1877-1884) 34.85 14.25 49.1 71
    Boston Three Star (1875-1910) 33.65 15.75 49.4 68
    Boston Band Model (1860-1895) 32.9 18.25 51.15 64
    Courtois Levy Model (1870-1910) 32.85 19.25 52.1 63
    Unsigned (Seltmann) rotary (1865-1875) 27.5 24.25 51.75 53
    Distin (ca. 1850) 24.13 25.75 49.88 48
    Guichard cornopean (1835-1855) 31.5 22 53.5 59
    Trumpets:
    Bach 37 (1940-present; well…maybe) 36.5 17.63 54.13 67
    Schilke B5 (1965-present) 40.5 13.5 54 75
    Connstellation 38B (1955-1995) 35.625 17.75 53.625 67
    Olds Super 1932-1979) 37.25 16.5 53.75 70
    Martin Committee (1938 to 1968) 35.88 19.63 55.5 65
    Besson (1890-1938)) 36.5 16.75 53.25 69
    Stowasser (ca. 1880) 31.5 23 54.5 58
    Besson (ca.1870) 31 21.88 52.88 59
    Graves & Co (ca. 1845) 30.75 19.625 50.375 61
    Courtois G trumpet ca. 1870 47.25 14 61.75 77
    German G trumpet ca. 1860 43.75 15 63 69
     
  8. SteveRicks

    SteveRicks Fortissimo User

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    Yes, I think I know what you are talking about, but it was on just the leadpipe I think. Remember seeing several years back. Was I hand sketch, if I remember. Now, where was it. It was on an Olds.
     
  9. gordonfurr1

    gordonfurr1 Forte User

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    Yes....I think you are right...it WAS just a lead pipe. Forgotten about that little aspect. And indeed it was hand drawn.

    Prob not going to help me design a folded molded valueless pocket horn having three finger holes and the left hand cupping the bell to achieve reasonably most scales.
     
  10. SteveRicks

    SteveRicks Fortissimo User

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