Short Stroke Valves

Discussion in 'Trumpet Discussion' started by trumpetup, Aug 1, 2011.

  1. oldlou

    oldlou Forte User

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  2. trumpetnick

    trumpetnick Fortissimo User

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    Ivan, what do you make of this:

    Wedgwood Brass - Is it all Ovoids ?

    I've never played Denis' instruments, but among others, the defunct british great cornetist and trumpet player James Watson seem to have choosen Denis' cornet design in his latest years. (I have just found on the net, that Jim died in February - anyone knows anything about that?)?
     
  3. oldlou

    oldlou Forte User

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    In my search through my 'accumilation' of instruments I rediscovered that E.A.Couturier went another route to remove all impedance,( the bumps in the through ports of the valves ), by using slightly overdiameter valve pistons which could then have conical through tubes without any bumps. In theory this was great for fantastic tone production, BUT, fast fingered articulation suffered with the heavier and longer stroked valve pistons. I enjoy my Conical Bore By E.A.Couturier trumpet and cornet for relatively slow and melodic playing, but, a shorter stroke horn works better for me when playing anything like any of the advanced Arbans exercises. Personal preference or old age, I know.


    OLDLOU>>
     
  4. chapmand

    chapmand Piano User

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    I'm a little late getting in on this discussion.
    I haven't measured the strike length of my 2070s, but they definitely feel shorter.
    As well the Phaeton horns advertise a short throw.
    Again I have not measured it yet.
     
  5. tptshark

    tptshark Pianissimo User

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    I've a feeling some Selmers (vintage and new) have a slightly shorter valve stroke.
     
  6. trumpetsplus

    trumpetsplus Fortissimo User

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    I don't know these instruments apart from what I have seen on his website.

    My question would be:
    Can the idea of ovality in the valve cluster tubing coexist with the idea of ensuring that the tubing in the bell crook is absolutely round?:dontknow:
     
  7. hup_d_dup

    hup_d_dup Piano User

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    Rather than estimating the length of the stroke, it can quickly and accurately be measured by measuring the offset distance between a set of the twin vertical ports in one of the valve pistons (assuming that the valves are correctly aligned).
     
  8. trumpetsplus

    trumpetsplus Fortissimo User

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    Make sure that you are measuring between the "front" ports or the "rear" ports and not the ports which present to the valve slide.

    If you have a digital caliper, measure the diameter of one port (they will be the same), then zero the calipers. If you then measure from the top of the top port to the bottom of the bottom port, you caliper will be reading the "center to center" distance, which is your stroke. Call this measurement #1.

    Then put the valve back in, remove the bottom cap and zero your calipers at the bottom heel of the valve in its up position. Push the valve down and measure this distance and call it measurement #2. If measurements #1 and #2 are the same, then your valves are stroking correctly. If they are stoking correctly and the ports are aligned with the slide tubing when the valve is depressed, then you valve is probably aligned pretty well. Further inspection of how the front and rear ports present to the tubing will give more indication of how well the valves are aligned.

    Proper valve alignment is normally a balance between all these factors, and, at best, will only be a "best fit".
     
  9. hup_d_dup

    hup_d_dup Piano User

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    Excellent, Ivan. This should probably be a "sticky." (Sticky thread, not sticky valve)
     
  10. veery715

    veery715 Utimate User

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    The answer to that question is yes. A cylinder off-center through another cylinder results in an oval shaped entry and exit. The passage is still a cylinder, but the entry and exit shapes as they appear on the face of the valve piston cylinder are OVOID. Moving the passages off-center also allows them to coesxist with other off center passages w/o the interference which produces the bumps seen in axially ported pistons.

    BTW, axially bored ports, while cylindrical, actually create elipses on valve surface.

    The other important design feature, is the pistons are somewhat larger in diameter, which allows more room for the ports to be off-center and reduces the throw.
     

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