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Thread: Gap - Adjustable Gap Receiver - No Gap

  1. Question Gap - Adjustable Gap Receiver - No Gap

    I´ve just read an article about Adams´ adjustable gap receiver and checked my Sterling Virtuoso (built 2008). From what I see with a torch: There is a smooth transition from the mouthpiece receiver into the leadpipe. No gap intended. How are your horns constructed? Among trumpeters there seems to be a lot of discussion about "the gap". Adams even put an adjustable gap receiver on their Euphoniums and leave musicians with lots of choices. Why don´t they make Euphoniums with a smooth transition? Are there different philosophies of the makers regarding gap or no gap? I wonder what´s it all about.

  2. #2
    Join Date
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    You won't really have a smooth transition unless the end of your shank abuts the end of the receiver (actually, the lead pipe -- see below) so that there is no "step" between the end of the shank and the receiver wall. So I'm highly skeptical that your Sterling has a smooth transition -- or that you would be able to see this by looking with aid of a torch (which I take it to be British for "flashlight" and not something like a Butane torch ). So my guess is that you didn't look down through the mouthpiece as it was inserted in the receiver and determine that the transition from end of shank to receiver/lead pipe was smooth.

    There's no way to construct a universal receiver so that it would provide a smooth transition of this sort for every mouthpiece shank (because of differences in diameter and wall thickness). (I seem to recall that some Monette instruments are made with an integral -- non-removeable -- mouthpiece?) So there WILL be some sort of step or abrupt transition from the shank to the lead pipe. Unless your Sterling has it's receiver as an integral part of the lead pipe? Try very carefully inserting something like a small dowel or plastic straw or rod down your receiver and you will probably feel a lip where it joins the lead pipe.

    In addition, every receiver I know of on euphoniums and tubas, etc. is soldered onto the end of the lead pipe. So the end of the lead pipe fits INTO the receiver and is then soldered. This means that there are (at least generally) TWO non-smooth transitions: shank end to receiver, and receiver to lead pipe. Thus a "gap".

    The adjustable gap receiver ... er ... adjusts this gap. (Trombones are a little different since the receiver is -- generally, modulo some King ones -- integral with the rest of the lead pipe, but there's then a step transition from the end of the lead pipe to the inner slide.)
    Gary Merrill
    Wessex EEb Bass tuba (Denis Wick 3XL)
    Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
    Amati Oval Euph (DE N106, Euph J, J6 euph)
    1924 Buescher 3-valve Eb tuba, modified Kelly 25
    Schiller American Heritage 7B clone bass trombone (DE LB K/K9/112 Lexan, Brass Ark MV50R)
    1947 Olds "Standard" trombone (Olds #3)

  3. #3
    Join Date
    Jan 2006
    Location
    West Palm Beach, FL
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    From what I understand, it's better to have a bit of a gap between the mpc shank and the lead-pipe. It helps with response and a little bit with tone. For more information, check out Dave Werden's video on the Adams euphonium. Slide the playback forward to just past 4 mins to see the discussion on the AGR.

    Discussing the Adams Custom Euphonium

    Rick Floyd
    Miraphone 5050 - Warburton Brandon Jones sig mpc
    YEP-641S (on long-term loan to grandson)
    Doug Elliott - 102 rim; I-cup; I-9 shank


    "Always play with a good tone, never louder than lovely, never softer than supported." - author unknown.
    Symphonic Band of the Palm Beaches
    Russian Christmas Music (Alfred Reed)
    El Cumbanchero (Rafael Hernández) cell phone video

  4. #4
    As I recall from my own Sterling, there is a "bump" in there, but it is probably more subtle than you are expecting. The bump is only caused by the thickness of the leadpipe tubing, so it is no greater than the thickness of the end of the tuning slide tubes.
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams Artist (Adams E3)
    YouTube: dwerden
    Facebook: davewerden
    Twitter: davewerden
    Instagram: davewerdeneuphonium

  5. Allow me to try to explain....
    In my Sterling, the inner diameter at the end of the receiver and the inner diameter of the mouthpipe where it meets the receiver without a gap are the same. The receiver-and-pipe unit is tapered to meet the taper of the mouthpiece. My mouthpiece rests in the receiver just beyond the place where leadpipe and receiver is soldered together. No rattle, no fuzzy tone, normal position. Much like a Cornet receiver. No Gap!?

  6. #6
    OK, so I think you are saying that without the mouthpiece inserted there is a bump, roughly where the end of the shank would be, correct? And that the end of the shank and end of the leadpipe mate virtually perfectly?

    If so, they you have a zero-gap setup...with the current mouthpiece.

    Did you read this article?
    http://www.dwerden.com/forum/entry.p...e-Gap-Receiver

    In my tests I found that there was a difference of 3.6mm between two of the mouthpieces' insertion depth. If your gap is zero now, it's possible that a different mp would either bottom out and rock in the receiver or that it would create a gap. That's partly why the AGR is there. At the bottom of the linked article above are some links to Harrelson's blog, which talks more about the gap and its effects. It has a little summary, which I will reformat here:

    Wide Gap (mouthpiece shank may be shorter)

    • More Air Resistance
    • Less Intonation Control
    • Hard Slotting
    • Less Flexibility
    • Need Less Aperture Control


    Medium Gap (Recommended)

    • Medium Air Resistance
    • Balanced Slotting & Flexibility


    Small or Zero Gap (mouthpiece shank may be long)

    • Less or No Air Resistance
    • Considerable Intonation Control
    • Loose Slotting
    • Incredible Flexibility
    • Need More Aperture Control
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams Artist (Adams E3)
    YouTube: dwerden
    Facebook: davewerden
    Twitter: davewerden
    Instagram: davewerdeneuphonium

  7. #7
    It is possible to machine a groove in the end of the receiver so that the leadpipe fits perfectly in. My besson Prestige baritone is built this way. It's also possible to put a taper for the mouthpiece directly into the leadpipe and just reinforce this with the receiver itself fitting over the leadpipe. Most trombones are made this way.

    I think the gap itself matters less than the overall taper you get connecting the backbore of the mouthpiece to the taper of the leadpipe. Having the mouthpiece end fit perfectly against the beginning of the leadpipe so there is no gap at all usually means that there's a large jump in the taper you get from the mouthpiece as compared to the taper at the start of the leadpipe. This is more harmful than the actual gap.

    I'm not a big fan of AGRs, though, I would prefer just to experiment with having the mouthpiece stem modified so it works optimally.
    --
    Barry

  8. #8
    Check out this link from GR mouthpieces: http://www.grmouthpieces.com/gap.html

    My thought is that the ideal starting point is where you can draw a dotted line connecting the taper of the mouthpiece backbore and meet perfectly the start of the leadpipe. This is almost certainly not where there is zero gap. And then you can move it a little in or a little out from there to fine tune slotting and resistance.
    --
    Barry

  9. #9
    Quote Originally Posted by bbocaner View Post
    I think the gap itself matters less than the overall taper you get connecting the backbore of the mouthpiece to the taper of the leadpipe. Having the mouthpiece end fit perfectly against the beginning of the leadpipe so there is no gap at all usually means that there's a large jump in the taper you get from the mouthpiece as compared to the taper at the start of the leadpipe. This is more harmful than the actual gap.
    Right. If the end of the shank were made as thin as the leadpipe tubing, it would be very subject to deformation. So even with the AGR there is still a thickness jump.

    Quote Originally Posted by bbocaner View Post
    I'm not a big fan of AGRs, though, I would prefer just to experiment with having the mouthpiece stem modified so it works optimally.
    Different strokes! Normally I'm all for a simpler design where practical. For example, I don't have a trigger on my Adams even though it would be handy every now and then. But it's not necessary and it is an extra point of maintenance or failure (an airline proved that concept on my Sterling with a trigger). I would typically feel the same about something like the AGR, but I have found it useful enough to justify the extra mechanism.
    Dave Werden (ASCAP)
    Euphonium Soloist, U.S. Coast Guard Band, retired
    Adams Artist (Adams E3)
    YouTube: dwerden
    Facebook: davewerden
    Twitter: davewerden
    Instagram: davewerdeneuphonium

  10. #10
    Join Date
    Dec 2011
    Location
    Central North Carolina
    Posts
    2,035
    Quote Originally Posted by bbocaner View Post
    It is possible to machine a groove in the end of the receiver so that the leadpipe fits perfectly in.
    Fits perfectly in, in the sense that the transition between receiver and leadpipe is smooth?

    But then you still don't have a smooth transition between the end of the shank and the leadpipe. You don't actually have a "gap", but there might be similar turbulence effects.

    I have no idea how important these miniscule differences may be. But I've seen some people express concern that on Schilke mouthpieces, the inside of shank end is chamfered.

    Not sure how much of this is empirically based or just speculative.
    Gary Merrill
    Wessex EEb Bass tuba (Denis Wick 3XL)
    Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
    Amati Oval Euph (DE N106, Euph J, J6 euph)
    1924 Buescher 3-valve Eb tuba, modified Kelly 25
    Schiller American Heritage 7B clone bass trombone (DE LB K/K9/112 Lexan, Brass Ark MV50R)
    1947 Olds "Standard" trombone (Olds #3)

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