Rifled backbore??

connloyalist · 06-03-2006, 05:17 PM

I read an article in a magazine about this:

http://www.exbrass.de/index.php?opti...106&lang=en_gb

(the translation from German to English isn't that good, but they get the point across).

Has anyone heard of this before? Comments? I am not personally interested, call this intelectual curiosity.

Regards, Christine

Solar Bell · 06-03-2006, 05:24 PM

Double, sorry.

-cw-

Solar Bell · 06-03-2006, 05:27 PM

I'm not sure...

But I think "Frank" from Berlin plays, or has one.

See link...
http://www.trumpetmaster.com/forums/...re+turbo#69442

-cw-

connloyalist · 06-03-2006, 05:33 PM

Ah yes!

Regards, Christine

NickD · 06-04-2006, 12:28 AM

I took a look at the site. The effect they show with the water is very real. Just try it with any empty two liter bottle. In physics speak, we are dealing with the conservation of angular momentum in a vortex and the ability to exchange the air and water more quickly.

The catch as I see it is that, once the air gets beyond the vibrating lip aperturture, the actual air speed drops very dramatically (Bernoulli effect). In the end there are two components in playing a trumpet: AC and DC. The AC part involves the notes. That's what is important in the long run. The DC part is the air flow through the horn. That DC flow has but one purpose; it allows us to keep the lips vibrating. However, the air doesn't even have to go through the horn at all to play it!

Check some back ITG journals. A few years ago a study was done with a trombone mouthpiece which had the shank sealed off with a piece of flexible mylar. Sound coud go through it, but no air! They simply drilled the hole in the SIDE of the mouthpiece and allowed the air to vent that way. They could play the trombone just fine. I do the same demo, but I couldn't get very good acoustic coupling to the lead pipe with the end of a trumpet moutpiece sealed off that way, so I simply sealed the bell with a tight piece of mylar. I could get no air through the horn, but it would play just fine, albeit with a muted sound with a vented mouthpiece.

The trick is the reisistance of the vent hole. To adjust it I would insert different lengths of coffee stirrers just the right diameter into the vent hole. I found an optimal length (resistance) for the horn to play. This was also in the article.

OK, to the point. The discovery expressed in the article was that there was an optimal resistance: too much and you could barely play the horn. Too little and there were no slots.

Well, a rifled backbore MIGHT make the air go through faster, but the situtation is different from the water bottle. We are not exchanging water for air under the influence of gravity in a closed bottle with no "push" from behind. I guess the vortex in the throat could make the air go through more easily, but I'm not sure the mechanism is quite the same. It doesn't really have to go through that fast (this is beyond the lips, don't forget). The rifled backbore may very well adjust the resistance a bit, and the slight spiral imparted to the air will certainly contribute to that. Maybe it is better to reduce the resistance this way rather than drilling open the throat a bit. There may be a slight acoustic contribution as well (like the old Zottolla stepped backbores or Pilcziuk lead-pipes). A vortex certainly does have frequency content (just look at how a flute, pennywhistle or organ pipe works!). In the end, I would bet on a subtle adjustment in the playing characteristics as a result of rifling the backbore. Some trumpeters might very well notice this. I'm not sure I agree with their acoustic analysis (air spiraling around the standing wave). Given that the speed of sound is on the order of 34000 cm/s and the air drift speed is on the order of 10 cm/s, I have a hard time imagining much change in the standing wave due to a vortex in the DC component. I can see the introduction of some new harmonic structure, though, possiby.

Frankly, I am very curious! I like horsing around with stuff like this! To reiterate, my instincts say "subtle difference at best." However, I could be totally wrong! It might be really obvious to the player. I'd check 'em out! They sure look cool.

BTW, here's another fun trick to take the wind out of trumpeters sails. I do this every year in my classes, mainly to freak out my students who don't know about my double life. I take my trumpet into the classroom, whip it out and without warning, uncork the loudest high A I can muster. Heh! That really shakes 'em up, especially for a first period class! Then I challenge them with a question. What would happen to a bubble formed if I dipped my bell in soap solution? You can guess that most kids will take the sucker's route and say "the bubble will fill up and burst in an instant!"

OK, I'm sure you know the real answer. With a decent bubble film in the bell, I can blow till I'm blue in the face, and I can't burst the bubble. The sound goes right through it. Even at 120 dB just beyond the bell, the actual air displacement is too small to burst the bubble and the DC flow is so small it takes about five minutes to inflate the bubble to a sufficient diameter (depending on the solution it can be up to two feet!) to pop it. You can estimate the number of liters per minute and then do a Bernoulli calculation to estimate the airspeed at the end of the mouthpiece throat. It is on the order of a few centimeters a second. You can't even blow out a candle with a trumpet!

OK, that's enough! In any case, try one of these and see if the riflings make a difference!

Peace!

Nick

Z4ME · 06-07-2006, 01:41 PM

Question for Nick:

Would the direction of twist (vortex- left or right) have any effect?

Thanks,

DJ

Eclipsehornplayer · 06-07-2006, 03:28 PM

I never thought about any of this stuff...

Fascinating!

Schwab · 06-08-2006, 09:39 AM

I played several Romeo Adaci mouthpieces with the rifled backbore at Felix's New York Trumpet Company booth at the ITG. I kind of thought it was a gimmick, but they all played really well, I was pleasently surprised!

Manny Laureano · 06-08-2006, 10:05 AM

Does it go the other direction if you play trumpet in Australia ?

ML

06-03-2006, 05:17 PM	#1 (permalink)
connloyalist Pianissimo User Join Date: May 2006 Location: Netherlands Posts: 66	Rifled backbore?? I read an article in a magazine about this: http://www.exbrass.de/index.php?opti...106&lang=en_gb (the translation from German to English isn't that good, but they get the point across). Has anyone heard of this before? Comments? I am not personally interested, call this intelectual curiosity. Regards, Christine

06-03-2006, 05:24 PM	#2 (permalink)
Solar Bell Moderator Fortissimo User Join Date: May 2005 Location: Metro Detroit Posts: 4,019	Double, sorry. -cw- __________________ Chuck Willard *The Willard of Oz* "Don't be afraid to see what you see." Ronald Reagan

06-03-2006, 05:27 PM	#3 (permalink)
Solar Bell Moderator Fortissimo User Join Date: May 2005 Location: Metro Detroit Posts: 4,019	I'm not sure... But I think "Frank" from Berlin plays, or has one. See link... http://www.trumpetmaster.com/forums/...re+turbo#69442 -cw- __________________ Chuck Willard *The Willard of Oz* "Don't be afraid to see what you see." Ronald Reagan

06-04-2006, 12:28 AM	#5 (permalink)
NickD Mezzo Forte User Join Date: Feb 2004 Location: Chicago northern suburbs Posts: 826	Yeah, but... I took a look at the site. The effect they show with the water is very real. Just try it with any empty two liter bottle. In physics speak, we are dealing with the conservation of angular momentum in a vortex and the ability to exchange the air and water more quickly. The catch as I see it is that, once the air gets beyond the vibrating lip aperturture, the actual air speed drops very dramatically (Bernoulli effect). In the end there are two components in playing a trumpet: AC and DC. The AC part involves the notes. That's what is important in the long run. The DC part is the air flow through the horn. That DC flow has but one purpose; it allows us to keep the lips vibrating. However, the air doesn't even have to go through the horn at all to play it! Check some back ITG journals. A few years ago a study was done with a trombone mouthpiece which had the shank sealed off with a piece of flexible mylar. Sound coud go through it, but no air! They simply drilled the hole in the SIDE of the mouthpiece and allowed the air to vent that way. They could play the trombone just fine. I do the same demo, but I couldn't get very good acoustic coupling to the lead pipe with the end of a trumpet moutpiece sealed off that way, so I simply sealed the bell with a tight piece of mylar. I could get no air through the horn, but it would play just fine, albeit with a muted sound with a vented mouthpiece. The trick is the reisistance of the vent hole. To adjust it I would insert different lengths of coffee stirrers just the right diameter into the vent hole. I found an optimal length (resistance) for the horn to play. This was also in the article. OK, to the point. The discovery expressed in the article was that there was an optimal resistance: too much and you could barely play the horn. Too little and there were no slots. Well, a rifled backbore MIGHT make the air go through faster, but the situtation is different from the water bottle. We are not exchanging water for air under the influence of gravity in a closed bottle with no "push" from behind. I guess the vortex in the throat could make the air go through more easily, but I'm not sure the mechanism is quite the same. It doesn't really have to go through that fast (this is beyond the lips, don't forget). The rifled backbore may very well adjust the resistance a bit, and the slight spiral imparted to the air will certainly contribute to that. Maybe it is better to reduce the resistance this way rather than drilling open the throat a bit. There may be a slight acoustic contribution as well (like the old Zottolla stepped backbores or Pilcziuk lead-pipes). A vortex certainly does have frequency content (just look at how a flute, pennywhistle or organ pipe works!). In the end, I would bet on a subtle adjustment in the playing characteristics as a result of rifling the backbore. Some trumpeters might very well notice this. I'm not sure I agree with their acoustic analysis (air spiraling around the standing wave). Given that the speed of sound is on the order of 34000 cm/s and the air drift speed is on the order of 10 cm/s, I have a hard time imagining much change in the standing wave due to a vortex in the DC component. I can see the introduction of some new harmonic structure, though, possiby. Frankly, I am very curious! I like horsing around with stuff like this! To reiterate, my instincts say "subtle difference at best." However, I could be totally wrong! It might be really obvious to the player. I'd check 'em out! They sure look cool. BTW, here's another fun trick to take the wind out of trumpeters sails. I do this every year in my classes, mainly to freak out my students who don't know about my double life. I take my trumpet into the classroom, whip it out and without warning, uncork the loudest high A I can muster. Heh! That really shakes 'em up, especially for a first period class! Then I challenge them with a question. What would happen to a bubble formed if I dipped my bell in soap solution? You can guess that most kids will take the sucker's route and say "the bubble will fill up and burst in an instant!" OK, I'm sure you know the real answer. With a decent bubble film in the bell, I can blow till I'm blue in the face, and I can't burst the bubble. The sound goes right through it. Even at 120 dB just beyond the bell, the actual air displacement is too small to burst the bubble and the DC flow is so small it takes about five minutes to inflate the bubble to a sufficient diameter (depending on the solution it can be up to two feet!) to pop it. You can estimate the number of liters per minute and then do a Bernoulli calculation to estimate the airspeed at the end of the mouthpiece throat. It is on the order of a few centimeters a second. You can't even blow out a candle with a trumpet! OK, that's enough! In any case, try one of these and see if the riflings make a difference! Peace! Nick __________________ NickD "Free Online Lessons in Extreme Trumpet Playing" http://www.nickdrozdoff.com http://www.newyorktrumpetcompany.com/ http://www.myspace.com/nickdrozdoff

06-07-2006, 03:28 PM	#7 (permalink)
Eclipsehornplayer Forte User Join Date: Sep 2005 Location: Flat Rock, Michigan Posts: 2,395	I never thought about any of this stuff... Fascinating! __________________ Eclipse MHY Bb Trumpet with interchangable leadpipes Bach 229 25A C Trumpet Getzen Capri Bb Cornet GR & Monette mouthpieces

06-03-2006, 05:33 PM	#4 (permalink)
connloyalist Pianissimo User Join Date: May 2006 Location: Netherlands Posts: 66	Ah yes! Regards, Christine

06-07-2006, 01:41 PM	#6 (permalink)
Z4ME New Friend Join Date: May 2005 Posts: 10	Question for Nick: Would the direction of twist (vortex- left or right) have any effect? Thanks, DJ

06-08-2006, 09:39 AM	#8 (permalink)
Schwab Moderator Forte User Join Date: Feb 2004 Location: the road Posts: 1,055	I played several Romeo Adaci mouthpieces with the rifled backbore at Felix's New York Trumpet Company booth at the ITG. I kind of thought it was a gimmick, but they all played really well, I was pleasently surprised! __________________ Dylan Schwab Stage 1 New York

06-08-2006, 10:05 AM	#9 (permalink)
Manny Laureano Utimate User Join Date: Sep 2004 Location: USA Posts: 5,989	Does it go the other direction if you play trumpet in Australia ? ML

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