TubeNet

All you engineer types out there ... take a look at this euphonium with 90 degree turns instead of smooth curves .


http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &rd=1&rd=1

How will those 90's affect the playablity and sound of the horn ?

Air vibrates within the horn. The volume of air flow through the horn is very low. If this were an air flow through the horn issue, my .709 bore horn should put up more back pressure than my .770 bore horn; but the opposite is the case. The .709 bore is quite a bit freer on the lowest notes and is a pleasure to play. If it weren't for bigger sound of the .770 horn, it would be sitting around collecting dust.

Never played one, seen one, etc., but thought this might be of interest:

This tuba, from Daniel Kunst's shop in Bremen definately has the 90 degree bend thing down...



More here: http://www.kunst-brass.de/Bilder/tuba_frontseite.JPG

oldbandnerd wrote:How will those 90's affect the playablity and sound of the horn ?

first of all, it's only on the 4th valve, so the short answer is "not much... "

and secondly, all those half circle bows in a regular euphonium are two 90° bends put back-to-back, so the long answer is "not much... "

As long as the bore stays constant, and without too many extra bends, is my guess, regardless of how it may look

Tom wrote:Never played one, seen one, etc., but thought this might be of interest:

This tuba, from Daniel Kunst's shop in Bremen definately has the 90 degree bend thing down...



More here: http://www.kunst-brass.de/Bilder/tuba_frontseite.JPG

This horn's been discussed here and here previously. I still maintain that it's got just as many 90 degree angles as any other rotary tuba.

no comment has been made on the valve throws. It's interesting that the 3rd valve has the longer linkage, which combined with the natural comparative weakness of that digit could lead to technique problems.

I know a lady who has a lot of 90 degree angles in her physique. She's still fun to hug.

eupher61 wrote:no comment has been made on the valve throws.

Notice there's no prices on his site anymore.

Buy one and tell us. The price (as of 1.5 years ago) converted to today's US$ is a mere $24,866.20. Almost as good as a Thein.

As far as 90 degree bends go, I play on a Gronitz pf125, witch has lots of 90's on the 3rd and 4th valve tubing. It is a very friendly horn to play, and is in no way stuffy. I have also tried a PCK, and there are plenty of 90's on that too. It was very, very easy to play. Honestly, I was quite surprised! I haven't had the chance to play too many BAT's, but this one played easier than my 4/4!

I do wonder if these horns would be even better without the 90 degree bends, though.

Has anyone tried to measure the actual airspeed through valve combinations? I'm no engineer, nor do I even play one on TV, but I'd be very surprised if much air actually flows THROUGH the horn. I thought this was mostly about standing waves, and the air flowing through the lips to initiate them.

windshieldbug wrote:Has anyone tried to measure the actual airspeed through valve combinations? I'm no engineer, nor do I even play one on TV, but I'd be very surprised if much air actually flows THROUGH the horn. I thought this was mostly about standing waves, and the air flowing through the lips to initiate them.

You are correct.... very little air actually flows through the horn. The sound waves only depend on air to carry them through the horn.

Thanks for confirming that, Dan.

fifthnotules wrote:I do wonder if these horns would be even better without the 90 degree bends, though.

You can get 'em that way -- they're called alphorns (fun to play, but a tad unwieldy, esp. for marching ) ...

Kevin Hendrick wrote:You can get 'em that way -- they're called alphorns (fun to play, but a tad unwieldy, esp. for marching ...

Yes, but you can't beat them if you need a quick pipe after a concert!

windshieldbug wrote: I'm no engineer, nor do I even play one on TV,

Choo, Choo!!!sorry, couldn't resist...

Tom wrote:Never played one, seen one, etc., but thought this might be of interest:

This tuba, from Daniel Kunst's shop in Bremen definately has the 90 degree bend thing down...

Except that to be functional, the valves still either contain 90° bends, or contain airways that have to cross, which STILL means you have to have the "dreaded" 90° bends... (work it out!)

zoro wrote:

schlepporello wrote:

Brassdad wrote: Choo, Choo!!!sorry, couldn't resist...

I'm in Durango, Colorado right now. My wife and I have tickets on the narrow gauge railroad here for tomorrow morning.
Jealous?

Yes

Likewise!

windshieldbug wrote:Has anyone tried to measure the actual airspeed through valve combinations? I'm no engineer, nor do I even play one on TV, but I'd be very surprised if much air actually flows THROUGH the horn. I thought this was mostly about standing waves, and the air flowing through the lips to initiate them.

I am persuaded that "stuffy" means lack of resonance, not lack of air movement. If a note's ease of speaking is picky about the air flow or embouchure (or both) we complain that it's stuffy, or that it backs up on us.

Some instruments lose their characteristic resonance when air flow exceeds a certain amount, and this could be because of pressure pockets caused by the geometry of the tubing. The things that project into the air flow cause these anomalies, but I think the taper design is still much more important to basic resonance.

A good buzz requires air flow to work against the elasticity of the lips. Good resonance reinforces that buzz by adding each pulse of air from the lips to the pressure waves reflecting back from the bell efficiently. More air does not mean more pressure--pressure is not produced by air supply, but rather by restrictions on its subsequent movement. When our pulses fit neatly into the standing waves inside the tuba, it's easy to let more air flow into it without having to push. So, poor resonance can provide a restriction on air flow. Powering through that restriction can sometimes cause alternate resonances that are unmusical. More often, though, we don't play in tune with the resonance of the instrument by putting in a clean and efficient buzz, and try to compensate by pushing more air. That produces noise in the vibration, which we think of as a spreading or unfocused sound.

An ideal instrument provides just enough natural air resistance to allow the buzz to maintain efficiency, and an abundance of natural resonance to make full use of the buzz we produce. Distance from that ideal undermines our buzz and the product of our buzz, and that's what makes a tuba stuffy. But both characteristics have to work together. Air resistance may or may help or hurt buzz efficiency in any given instrument.

Rick "for whom 'open' means 'resonant'" Denney

Edit: On the subject of air speed, for uncompressible fluids flow equals velocity times area. Let's assume air is not compressible (which is a false assumption, but useful). Further, let's assume that we can empty our lungs on a pedal tone in two seconds. We will be dumping perhaps 2 liters per second, which corresponds fairly closely to Jacob's measurements of 140 liters/minute for low, loud notes on the tuba.

A liter is 1000 cubic centimeters, so we are moving 2000 cm^3/second through the mouthpiece throat. The mouthpiece throat is perhaps .84 cm in diameter, which has an area of .55 cm^2. If we were blowing water instead of air, velocity would be 3.6 m/sec, which is about 25 mph. When that flow expands to fill a .75" tube, velocity would drop by a factor of five, to .7 m/s, or maybe 5 mph. At a 20" bell, the velocity drops by a factor of 3600, to .001 m/s or .007 mph. Air is compressible and pressure will increase in smoothly in response to restrictions, with the sound pressure waves riding on top of it. But it gives you a notion of how much air speed slows down in the instrument. You can feel that difference in warmth when playing on a cold day.

R "who forgot to answer the question first time around" Denney

Rick Denney wrote:I am persuaded that "stuffy" means lack of resonance, not lack of air movement. If a note's ease of speaking is picky about the air flow or embouchure (or both) we complain that it's stuffy, or that it backs up on us

That sure resonated here!