How long is a cornet?

Discussion in 'The Rehearsal Room' started by alanl58, Aug 22, 2005.

  1. alanl58

    alanl58 Member

    A friend has volunteered to give a talk to the local WI about brass bands and the instruments.

    She casually asked if anyone knew how long an instrument would be if it was opened out straight, taking a cornet as an example. No-one knew the answer.

    Can any tMPers point me at a web site, or indeed know the answer?

    Mathematically if middle A is 440 hZ, then I reckon this has a half wavelength of 1.06 metres to resonate. Am I anywhere near the answer?

    Alan Lafferty
    St Gennys Silver Band
     
  2. GJG

    GJG Well-Known Member

    Going purely from memory, a Bb trumpet/cornet is about 4'6" give or take an inch or two. A 'C' trumpet is pretty much 4' exactly.
     
  3. MRSH

    MRSH Supporting Member

    THIS or THIS may be of help.

    Good luck
     
    Last edited: Aug 22, 2005
  4. MoominDave

    MoominDave Well-Known Member

    Yurr. Ish. The half wavelength of the pedal C (1st partial) on the Cornet is the same as the full wavelength of the 2nd partial (one leger line low C). Bearing in mind that a Cornet's C is actually a concert pitch Bb, the frequency of this 2nd partial is 440 divided by 2, times the twelfth root of 2, or about 233 Hz. The speed of sound in air is about 343 metres per second. Rearranging speed=frequency*wavelength and substituting in these values, we get a wavelength of about 1.47 metres, or 4 feet 9.8 inches. However, there is a complex correction to be made for the effect of the tapered end of the instrument, which reduces the length somewhat for a given pitch. If you want precise measurements, Arnold Myers at Edinburgh University is your man - see http://www.ph.ed.ac.uk/~am/research.html for details of him and some of his relevant work, though sadly no specific lengths.
     
  5. alanl58

    alanl58 Member

    Thanks everyone. Some very interesting reading.

    I think for the sake of a non brass - band audience we can say that a cornet is roughly between 1 and 1.5 metres long, dependant upon manufacture, bore, and bell size?

    Alan
     
  6. DublinBass

    DublinBass Supporting Member

    I usually just stick to 4' for a cornet, 6' for a tenor horn, 8' for a baritone, 12' for an Eb bass and 16' for a BBb bass as my estimates.
     
  7. MoominDave

    MoominDave Well-Known Member

    You can be a bit more precise than that with the lower bound - something like 1.35 metres ought to contain all the Cornets that have ever been made in Bb at A=440Hz.

    The "standard" measure is 4 and a half feet. You'll hear people talk about "4.5 foot Bb" for a cornet, "9 foot Bb" for a Euphonium (not 8! That's "8 foot C") and "18 foot Bb" for a Bb Bass. Pat's numbers are all slightly under; these are closer:

    3.25 (or 3 if you're being more generic) Soprano Cornet Eb
    4.5 Cornet Bb (i.e. 4 and a half - 4'6", not 4'5")
    5.5 G
    6 F
    6.5 Horn Eb
    7 D
    8 C
    9 Euphonium Bb
    11 G
    12 F
    13 Bass Eb
    14 D
    16 C
    18 Bass Bb
     
  8. DublinBass

    DublinBass Supporting Member

    AAAAAAGHH!!!

    I'm going to be scared for life now!!!

    ;)
     
  9. Keppler

    Keppler Moderator Staff Member

    It always amuses (and confuses) me when units are mixed like this. Oh well.. I'm a metric child, and still cant reckon in inches, yards, ells, fathoms, feet, arms, heads etc..
    I have no idea what a stone (weight) is, nor of the bits that make it up.. 1 stone = 1000 pebbles perhaps?

    Oddly enough, I know how long a cubit is though.

    Decimal Kepps.
     
  10. MoominDave

    MoominDave Well-Known Member

    I wouldn't use imperial, but it's how these things are normally quoted when talking about specific pitches. I suppose it's a hangover from Organ nomenclature, where you have 2', 4', 8', 16', etc. ranks of stops.

    That said, I did find myself defending the imperial system to a Russian this morning on the grounds that using it introduced children to intuitive concepts of different bases and fractions with non-terminating decimal representations early on. I don't think it was a terribly successful defence...

    Pat - don't worry; we all love you just as you are!
     
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  12. mikelyons

    mikelyons Supporting Member

    I've always had a problem with pedants. They are frequently unwashed, lazy and demand holidays...


    That said, there is, I believe a physical (scientific) reason for the use of 2' 4' 8' etc pitching in organ and other pipes, rather than this modern metric rubbish :p

    Pandering to the masses, I call it. The pedants are revolting... No wonder people can't add up these days. Counting in tens and hundreds! What's wrong with 12's and 16's and even the 14's (that's for you, Kepps! :))

    Nurse! Nurse!

    Oh, and I doubt most sincerely whether the ladies of the WI would be at all interested in micrometric measurements. Between 4 and 5 feet long should be as much as they need to know for the purpose of the talk. Besides, I rather suspect they would prefer demonstrations of the sound than dry discourses about the length of the tube.
     
    Last edited: Aug 28, 2005
  13. MoominDave

    MoominDave Well-Known Member

    Mike, you are magnificent. :tup
     
  14. mikelyons

    mikelyons Supporting Member

    :oops:

    (Erm.. what did I do to deserve that accolade?
    Is that official?):confused: ;)
     
  15. MoominDave

    MoominDave Well-Known Member

    You know! ;)

    p.s. Is that a real photo?
     
  16. trumpetmike

    trumpetmike Active Member

    Just buy a cheap cornet and unravel it - not only would you know exactly how long an instrument is, but you could prove it to your audience.
    On top of that - there would be one less cheap and nasty cornet in the world.

    I would ask for suggestions as to which brand to unravel, but that would be a whole new can of worms (I have too many suggestions - many of which some of you are probably playing on)
     
  17. mikelyons

    mikelyons Supporting Member

    It's a real photo of Lily Savage. At least in so far as we understand the term reality, and as real as a cyber image can be in a world of physical objects. If you see what I mean. ;)
     
  18. B'aht a band

    B'aht a band Member

    I am but a simple bass player, and you lot are truly confusing me!!

    :confused:



    Andy
     
  19. alanl58

    alanl58 Member

    In a "senior moment", well more an "inebriated moment" actually, I looked at the pub wall, and there, staring me in the face was a full post horn!

    Not the silly little things that will appear on "Bargain Hunt" in a few years when the huntsmen sell them, but a full length coaching type.

    Now I know the true length of a soprano cornet that has been straightened to see if it really can be played in tune......

    Now there is an interesting talk for the WI...............

    alanl58
     
  20. FlugelD

    FlugelD Member

    But did you measure the damned thing..? :rolleyes:
     
  21. DublinBass

    DublinBass Supporting Member

    As soon as I read his post, I was about to say the same thing!!!
     
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