WTB: "Elliptical" shaped trumpet tuning slides

Discussion in 'Bb Trumpets' started by Mal_Ray, Jun 22, 2016.

  1. Mal_Ray

    Mal_Ray New Friend

    Jul 14, 2012
    I believe I can produce elliptical shaped trumpet bells, however I need elliptical shaped tuning slides. Looking for a source. Harrellson is probably out as he's kinda priced his stuff out of the market for folks who make trumpets like I do. M&K...well I don't think they make ellip. slides and besides, I find them next to impossible to meet up with by phone or otherwise. Any sources? Oh Yeah, also Kanstul won't make them for me--probably figures the demand is not sufficient to make a profit or just doesn't want to develop new tooling. Getzen---I've never found Getzen to be cooperative in any way with independent trumpet makers and unwilling to sell any components. So who else????? Thanks!!
  2. Mal_Ray

    Mal_Ray New Friend

    Jul 14, 2012
    D slides v circular slides: Opinion only. Guys, I dealt with gaseous (vapor) fluids and liquids all through my 50 yr oil and gas career and produced patents in 68 countries for ultrasonics to measure vapor and liquid flow. Not that I might not wake up tomorrow and learn something new. But really, compared to the velocity of flow that I've dealt with (a very wide range) I am not totally certain but I believe the velocity of your air through your trumpet is really quite miniscule--especially when compared against so many other types of fluid flows----that there can not, IT SEEMS TO ME, really be any difference between the flow resistance in D slides v Circ slides, and even elliptical shaped slides. One man's opinion. Know that in engineering and manufacturing, your new trumpet may look and appear to be perfect----but it is far from perfect. There is no such thing as perfection in a manuf. process. So what I'm saying is that if you feel your circular tuning slide is easier to blow or provides you some other advantage, it could be entirely due to some very minor difference in manufacturing that say, affected perfection of internal wall, 'end-of-slide' tube edge configuration, or something else like that. So that you may have a slightly better situation with the circular slide, as an example, but it may be due to something other than the difference in D v. Circ. config. And keep in mind, in case I've set off some crazy debate, it's just one man's opinion.
  3. tubamuirum

    tubamuirum New Friend

    Jul 15, 2004
    West Sussex, UK
    Try Carol Brass? They supply components to small scale producers....
  4. Sethoflagos

    Sethoflagos Utimate User

    Aug 7, 2013
    Lagos, Nigeria
    Strong preference for 'D' shapes.

    Bends are difficult to get your head around so bear with me. But we'll not be talking viscous friction losses.

    The governing equations for the air column (in the absence of wall shear) don't include a bore term. The air column equations are identical whether it's a peashooter or 48" ND X70 API 5L pipeline ;-). So you are perfectly at liberty to treat the aircolumn as a million and one independent streamlines, all running moreorless in parallel. Independent only to a point. Everything works fine in straight tubing whether cylindrical, conical or horn curve. They just expand and contract as necessary to fit the profile and ALL STAY THE SAME LENGTH (important that bit).

    Bends pose a problem because now a streamline that hugs the outside of a bend is considerably longer than one that hugs the inside which will seriously mess up the sharpness of an attack. The million and one air columns will now be delivering their pressure pulses at the next node spread out over a long time (for an air column) and have the node jumping all over the place.

    Fortunately this isn't what happens in practice. And now we forget about air flow entirely - it's time-of-flight of the pressure waves in our million and one air columns that matters.

    Fire a pressure pulse into the cup and there's no issue through the mouthpiece and down the lead pipe. Neck and neck all the way. Until they hit the bend. Now the guys on the inside start creeping ahead of the ones further out. And now it's a lot easier for them to use their pressure advantage and nip into the low pressure zone of their outside neighbour than it is to stay tight on the corner. And so a domino effect starts with stuff on the inside moving outwards though the centreline of the tubing and the slow ones on the the outside being pushed around the tubing wall towards the inside.

    From end on it would look like two D-shaped eddies stuck face-to-face rotating in opposite directions (conservation of angular momentum thing).

    Anyway, the upshot is that for the right shape of bend, the twisting keeps all million and one air columns negotiating the bend with a much closer length distribution. So the pressure pulse arrives at the node as a united perpendicular plane wave and the node does what it should.

    Nodes within the curve of the bend are a little harder to resolve, but I think the dynamics still hold.

    Best regards,

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