C Trumpet Project

Discussion in 'Trumpet Discussion' started by Derrick, Apr 28, 2013.

  1. stumac

    stumac Fortissimo User

    Oct 19, 2008
    Flinders Vic Australia
    Be very wary of cheap Chinese C trumpets, I got one for a friend, the open notes were all flat, we fixed this by shortening the tuning slide by 1/2" the maximum without moving the forward brace. We then found the valve slides were all wrong, the 1st and third were midway between the Bb and C length and the 2nd was a Bb. Cutting all to correct length made a tolerable C instrument.

    25 years ago I converted a prewar Besson International Bb to C, I cut 1" off the bell tail, 1" off the leadpipe and 1" off each leg of the tuning slide. My reference was a well tuned piano in church. To get the valve loops in tune I used the instructions in the preface in the Arban Method, play a 4th space E open and 3rd, and adjust the 3rd slide until the notes are the same, play 3rd space C open and 2-3, adjust 2nd slide till notes the same, play 2nd line G open and 1-3 adjust 1st slide until notes are same. While this method may not be perfect it gave me a C trumpet to play in church for some years. My friend played it in orchestra for 3 years with no complaints.

    When I did this project I had no knowlege of acoustics or instrument design, only that a C should be about 4" shorter than a Bb, it was a case of Fools rush in.

    Regards, Stuart.
  2. Derrick

    Derrick New Friend

    Apr 4, 2013
    From what I understand, if done well and with a great amount of skill and luck, conversions can turn out surprisingly well. The question is, how much skill and luck will I have? I plan to do some cuts this weekend. Not sure how much or if I will get to soldering or not.
  3. Derrick

    Derrick New Friend

    Apr 4, 2013
    No silver solder at all? Hmm. Did not know that!
  4. Derrick

    Derrick New Friend

    Apr 4, 2013
    Hoping I get your luck! And using the Arbans preface is genius, I should have thought of that!
  5. Masterwannabe

    Masterwannabe Mezzo Piano User

    Sep 11, 2009

    I really didn't mean to suggest these things were the only things involved in doing a good conversion. I was simply trying to make an analogy re; both the C & Bb horns aren't really that far apart for those who think conversions from Bb to C are ill advised. I must say though that I am not quite sure what you mean about concept. As I stated earlier I am not a pro repair tech, I am trying to learn much of the trade in my old age as I like to learn new things and I am having a ball working on instruments. My first impressions re: concept would involve the initial design i.e. length of tubing to each curve, brace placement and I suppose all the other subtleties that go into initial engineering of the horn. I would think that concept could not be that involved since most of the design is already done and the only thing that one might be able to make an impact on would be brace placement if some needed to be moved. Please don't think I am trying to question your skills or knowledge, you have been trained in this, I am trying to learn and I am learning with the generous help & advice from folks like you and others who have been kind enough to show me some things. So, a little more detailed explanation of what you mean about concept would be greatly appreciated.


    Ray Z :play:
    If you don't know where you are going it doesn't matter how you get there.
  6. trumpetsplus

    trumpetsplus Fortissimo User

    Jun 11, 2006
    South Salem, NY
    Some concept/design questions which are not addressed by the designer of the donor Bb horn are:
    Where are you going to cut the 6.2" from to raise the open pitch from Bb to C.
    How much from the bell tail?
    How much from the lead pipe?
    Which part (front or back) of the lead pipe to shorten - (this is a biggie!)?
    And then how much from each leg of the tuning slide?
    Where will you place the 1st slide to bell tail brace?
    Where will you cut the third slide?
    Where will you place the third slide to lower tuning slide receiver brace?

    The more you get into it, the more you will realize that every little change alters the playing characteristics; sometimes for the good and sometimes not. But you don't get anywhere if you don't start.

    And always try to have in mind to stand on the shoulders of the great trumpet designers of the past - not on their faces.;-)
  7. Derrick

    Derrick New Friend

    Apr 4, 2013
    Ok everyone, my measurements are as follows. Please do keep in mind that although these measurements HAVE been tested and advised by other technicians and players, these may not work for every instrument. If you have a Fullerton Olds Ambassador laying around, however, you may be in luck!

    Main Tuning slide(male parts)-1 9/16"
    Main Tuning slide(female parts)-2 1/2"
    3rd Valve Slide(male)-1 5/16"
    3rd Valve Slide(female)- 1 9/16"
    1st Valve Slide(male)-1 1/16"
    1st Valve Slide(female)-1 1/4"
    2nd Valve Slide(male)-3/8"
    2nd Valve Slide(female)-1/2"

    I will be trying this without cutting the bell this time. If it doesn't turn out sounding good then I will know what to do next time and adjust my measurements accordingly!
    Last edited: May 1, 2013
  8. trumpetsplus

    trumpetsplus Fortissimo User

    Jun 11, 2006
    South Salem, NY
    Your dimensions are different to mine.
  9. trumpflugel

    trumpflugel New Friend

    May 2, 2007
    The Eterna Getzen on Ebay looks good. My C trumpet happens to be a Yamaha and I love it. Easy to play. I can transpose as I play, but I got lazy. Plus playing in churches out of their hymnal gets old on a B flat.
  10. tjcombo

    tjcombo Forte User

    Nov 12, 2012
    Melbourne, Australia
    Not sure whether to curse or thank you Derrick, I'm now eyeing off a couple junker horns that I resuscitated with a view to a conversion. It's like everyone needs more projects right? :-)

    If you're not going to cut the bell for your initial trial, you might want to get an old leadpipe from elsewhere that you can chop down because chopping 5 inches from your Ambassador pipe will render it useless thereafter.

    If you use an junk trumpet as a donor for the leadpipe you could also use the bell to mess around until you get the right lengths. (maybe a use for a Trident trumpet??) It's fairly easy to remove and replace this bit. It would avoid getting really weird results from taken all of the open length out of the leadpipe.

    You can also make sections to play with out of brass tubing from your local hobby shop. It's usually sold in 1 ft lengths in 1/32" diameter increments which telescope nicely. It's quite easy to anneal and swage an end with the shank of the right sized drill bit to fit onto existing parts of a horn.

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