Rifling the bore mouthpiece

[Scooter Pirtle]

I don't know about the rifling, but I've had pretty good luck with chrome lightning bolts mounted on a baritone.

The rifling works okay, but you must remember to keep the "safety" on at all times!

[Brent]

Is the theory on rifling similar to Acousticoil?

Frank Minear from Minnesota Brass used one of these. He was a phenomenal player and swore by this technology. As I remember the piece, it was different than on the Acousticoil website. It kind of rifled the air from a piece of plastic inserted into the lead pipe. More rifling than air disturbance/interference.

[HornsUp]

Acousticoil?

If you place ANY kind of obstruction somewhere into the bore of an aerophone, it will affect the pitch and response of several pitches. This is because it is influencing some nodal or antinodal pressure points. A dent in the tubing will behave in the same manner. Some of these influences may prove beneficial on a few random pitches, but it is likely that more will prove non-beneficial. (Urban legend: there is a certain vintage model of tenor sax that is reputed to play better when its mouthpiece cap is stashed in the bell bow.)

I met this Don Novi character many years ago at a Colorado state music convention. At the time, he was traveling about with a Unimat (miniature lathe) and permanently modifying his victims' trumpet pistons by offsetting the valve port alignment. (This of course could be easily and temporarily achieved just by changing out corks and felts.) Nowadays some players shell out big bucks to get a precision valve port alignment, the exact opposite technique.

So this P.T. Barnum of the brass world was rattling on about "constructive interference", a concept which somehow has never been discovered by all of the great acoustical physicists and instrument designers.

Eventually, he came up with a bore insert made from a thin sheet of plastic. And then, variations for different bore sizes. And a bent wire to position his gizmo in the bore of a horn. And the advice to fool around until you find the sweet spot for your particular instrument and playing technique.

Go ahead - shell out 40 bucks - and form your own conclusions.

[MiniSopGuy]

My first thought on this is there would be no benefit and could actually cause problems.

When you say rifling, of course I think about the rifling of a firearm barrel. Then thinking about the edges of the rifling, which are normally quite pronounced, and the sound wave that travels through the bore of the instrument, if one of the edges of the rifling ended up where a node of the sound wave should be, that would disrupt the sound wave and create pitch and slotting problems throughout the entire range of the horn. Also, to have any real effect to spiral the air flow through the entire horn, the rifling would have to be very deep.

Air does not have the same hydrodynamics that say a liquid does. Think about water going down a drain. If you stop the water briefly, due to gravity, it still continues to flow in a spiral motion down the drain. As soon as you stop the air pressure behind the sound, buy tonguing or changing pitch, and the fact that the velocity of the air is relatively low, the air movement through the horn stops and thusly the swirl effect you have created in the mouthpiece and lead pipe stops. The next time you attack a note, even in a 1/16 pattern at a fast tempo, the swirl effect will stop and restart with every note.

Now all of that said, I would love to have a mock-up done with clear tubing and put it on a flow bench to see what would really happen to the air flow.

[HornsUp]

.... and the sound wave that travels through the bore of the instrument ...

This is a common misconception. The sound wave does not travel through the bore, it is a standing wave.

[Jimisback]

As soon as it hits the valves it gets distorted. The bell is the resonator(sp). But will the rifling make it more centered? Or easier flow? Louder? Or weaker? Or NO effect at all ?????

[HornsUp]

The bell is the resonator

The entire instrument, AND the player's windway, is the resonator.

[Dave]

Talked to our repair tech about it. One problem is that most brass instruments don't have terribly thick walls; you wouldn't be able to do any kind of rifling deep enough where it might potentially make a difference without virtually cutting through the metal. Even then, you're still talking about a world of difference between the physics of soundwaves and the physics of a bullet.

[Shadow_7]

I've heard of some players that have a natural rifling to their airstream. A little easier to see as a trombone player. Take out the mouthpiece, take off the outer slide and look down 3'+ of straight tube. I don't know what artificially doing it would do if anything. If you live near the equator, does it have no effect? If you face east instead of west, does it have to opposite effect? If you're south of the equator is it rifled the wrong way? Is the optimal rifling different for playing high and low. Plus the other factors, low density air, thin metal alloys. It's probably more of an effort in futility than anything. Although it could provide some interesting critter realestate for a biological experiment.

[MiniSopGuy]

This is a common misconception. The sound wave does not travel through the bore, it is a standing wave.

Sorry I mis-typed that. I did not mean to insinuate that the sound wave travels all the way through the bore of the horn and out the bell, but rather how the sound wave moves within the bore, throughout the horn.