What in F tuba design makesthe low range stuffy (or not)

[sloan]

That would put a node at the lips and an antinode at the bell opening--when the pressure is high at the lips, it's low at the bell and vice versa.

this is confusing, to me.

I was under the impression that *pressure* is *constant* at the bell. *motion* varies - but *pressure* is constant (the point is that, no matter how hard you blow, you can't change the *pressure* of the surrounding atmosphere!). The mouthpiece end is much more complicated...I'd have to pull a book or two off the shelf to find the right diagram - but I know that Rick owns the same books, so I'll let him do it. If everyone falls silent, I'll do it...manana.

Please - no more "handwaving" until someone posts a diagram from an authoritative source!

I'll just add that finding nodes and antinodes is not as simple as measuring distance from the mouthpiece, or the bell. There's that nasty taper to deal with. not to mention the twisty-turny curved parts.

[sloan]

OK - my books are out on loan (again), so I'll take the lazy way out. Google "node antinode brass" and the second hit will give:

http://www.colorado.edu/physics/phys483 ... /n1106.htm" target="_blank" target="_blank" target="_blank

where you will find (my apologies for using the trumpet as the example...):

Flared Bell

Let's talk about a trumpet as a example. If there was not a flared bell the trumpet would have odd integer overtones. The flared bell (and to a lesser extent the mouthpiece) cause the overtones to be harmonic (almost). This is due to many years of artisans tinkering with various shapes and sizes for the bell. The original first natural mode is shifted upward and is not related in a harmonic way with the other normal modes which take on a frequency of 2f, 3f, 4f, ... with the fundamental missing. The missing fundamental can be played by careful control of the lips and heavily relying on the overtones, and is called the "pedal tone".

The natural modes of flared bells in combination with cylindrical and conical cavities are discussed in "The Physics of Musical Instruments", Fletcher and Rossing (1998), if you are interested in the actual solutions to the wave equation in these more complicated geometries.

Look at the diagram there under the heading "conical bore" - and then note that the flared bell effectively LENGTHENS the tube as the frequency goes up (I think I have that right - please do check with our friends Fletcher and Rossing - or find the Benade article in Scientific American on the Physics of Brasses).

To summarize: the tuba is best viewed as being OPEN on one end and CLOSED on the other, with a node at one end and an anti-node on the other. Ordinarily, this might lead to the conclusion that you can only get odd harmonics - but the flared bell changes the effective length of the tube so that you get 2f, 3f, 4f, ... (but note the absence of 1f!!!!!) There is a "first partial" but it's not in the 2f, 3f, 4f... harmonic series. If you object that "I can *hear* the fundamental, then consider the psychological implications of hearing a tone where 2f, 3f, 4f, 5f, ... are all present (but not f). Your brain (and perhaps your ears) inserts the 'f which *must* be there' (see also: Difference Tones).

Back to the point: computing node/anti-node locations using a very simple model of oscillations of a string WILL NOT WORK. Perhaps you have noticed that TUBAS ARE NOT STRINGS.

And anyway, String Theory is out of date - the current version is Membrane Theory, and (against all odds) the drummers are the new Kings of Physics.

[kingconn]

The lips are always a node and the bell is always an antinode. At the fundamental there are no other nodes. At the 2nd partial the node will actually be 2/3rds of the way down the tube. THis is because the wave halves will be equal. Of course the conical tube elongates this. The point is octaves don't mean halves.
mike

[Doug Elliott]

That's pretty much how I was looking at it, but Rick may be right... he probably knows more about it than the rest of us put together.

That scenario would definitely be true for a straight pipe, but the mouthpiece and bugle modifies the odd numbered harmonic frequencies to sound like a true harmonic series, which therefore also modifies the wavelengths as Rick said.

(Clarinets and saxophones are also closed-end tubes, but a clarinet doesn't modify the odd numbered harmonics because it's pretty much a straight pipe. Saxophones are tapered so they do modify it similarly to brass instruments.)

Sorry to hijack the subject of this thread.

[sloan]

The lips are always a node and the bell is always an antinode. At the fundamental there are no other nodes. At the 2nd partial the node will actually be 2/3rds of the way down the tube. THis is because the wave halves will be equal. Of course the conical tube elongates this. The point is octaves don't mean halves.
mike

First, the "fundamental" may not be the " first partial" - the relationship between the first partial and the second is an oddball one.

Second, all the "halves" are not equal - the taper does this to a given partial, and the flare of the bell makes the bugle longer at higher frequencies.

Which explains how you get 2f, 3f, 4f...but NOT 1f.

But that's just for starters - it's actually MUCH more complicated than that!

See Fletcher & Rossing.

[Doug Elliott]

"No 1f" applies to trumpets, which don't resonate a fundamental because the tubing is too small for it, or something like that. Flugelhorn and lower brasses do resonate the fundamental.

[jonesbrass]

I've been watching this thread since it started. I hate to sound like a big jerk, but here goes . . .

I think the single biggest reason that the low range on any instrument (not just F tuba, but it seems to be the main target due to tessitura) is stuffy is the player attached to the mouthpiece. Sorry, but I've got to call it as I see it. If a given instrument doesn't function the way you want, don't play that one, if you have a choice. If you don't have a choice, practice until you are in control . . . not the horn.

I will now dismount the soapbox . . . I apologize in advance if I've offended anyone. Of course, YMMV.

[ginnboonmiller]

I've been watching this thread since it started. I hate to sound like a big jerk, but here goes . . .

I think the single biggest reason that the low range on any instrument (not just F tuba, but it seems to be the main target due to tessitura) is stuffy is the player attached to the mouthpiece. Sorry, but I've got to call it as I see it. If a given instrument doesn't function the way you want, don't play that one, if you have a choice. If you don't have a choice, practice until you are in control . . . not the horn.

I will now dismount the soapbox . . . I apologize in advance if I've offended anyone. Of course, YMMV.

That's lovely and all, but...

I'm a pretty dang good tuba player. Some of the sweetest sounding F tubas that I've played had remarkably stuffy low Cs on them. It's true! I can make those low Cs sound great, and you would weep at the agonizing beauty of my musicality and all, but dang it, the low Cs are stuffy and take extra work. That's not me. Me is the way I am able to work around the stuffiness, but the stuffiness itself isn't me. On those tubas. Not on others that DON'T have stuffy low Cs, which is some tubas. It's up to the individual player to pick the right horn, and yes, it's much more important that you make good music than it is to have a solid low C, but you can't possibly tell me that different tubas don't have different little quirks and such. Is it worth discussing? I'd say it holds as much value as talking about the weather, which doesn't change the weather but we all talk about it, and that's perfectly okay.

[The Big Ben]

I've been watching this thread since it started. I hate to sound like a big jerk, but here goes . . .

I think the single biggest reason that the low range on any instrument (not just F tuba, but it seems to be the main target due to tessitura) is stuffy is the player attached to the mouthpiece. Sorry, but I've got to call it as I see it. If a given instrument doesn't function the way you want, don't play that one, if you have a choice. If you don't have a choice, practice until you are in control . . . not the horn.

I will now dismount the soapbox . . . I apologize in advance if I've offended anyone. Of course, YMMV.

You're not wrong and there is plenty on TubeNet to support you. Bloke wrote a prescription for folks with 'F Low Range Disease".

It's apples and oranges to the OPs topic. The OP asked: "We know some F tubas have better low ranges than others. Why is that?" Had some good input, including Sam, a maker of tubas who has practical experience and others who have a great technical knowledge of physics and design.

I've found it fascinating.

[awaters]

I always enjoy this thread in part because i don't understand science and am glad that there are tubists who do!
I had a B+S orchestral F and i switched from CC to F every note(a real pain... suggested by teacher but it worked) to get the low C on the F tuba to speak. I now play the Willson F which works fine on the C and notes down below.

[Rick Denney]

You have to "work" to get a low F on a BBb tuba?

Obviously either an inferior horn, or an inferior player.

Is the tuba for sale?

Only if you want it to sound good.

But, yes, on a Holton, the low F requires a special blow. It's not just push the buttons and blow. You have to feed the resonance, and if you force it, it will not sound. It's easier played 1-3 with a pull, but the potential sound isn't as big. The fourth valve has a larger bore, much like the fourth valve on B&S-style F tubas.

Rick "wondering why that would make the instrument unacceptable" Denney

[Rick Denney]

Many have complained about my description of nodes and antinodes, etc.

But here's what I know, and at the end what I suspect:

1. Nodes occur at the lips, and in whole wavelengths downstream from that point.

2. Antinodes are halfway between nodes, approximately (the approximate part is because of the taper).

3. The wavelength is what it is to produce the note in question. So, if an instrument playes a fundamental 26-Hz pedal Bb, the next node will be 43ish feet away from the mouthpiece. If that isn't the case, it won't be a 26-Hz Bb.

4. If an instrument plays a 58-Hz second-partial Bb, then the next node will be 21ish feet from the mouthpiece, which is a bit outside the bell. Obviously, the node is at (or near) the bell when playing the second partial, and the antinode is at (or near) the bell when playing the fundamental. I see no alternative from a physical point of view.

5. So, for calculating the fundamental, we must consider the instrument as closed on the mouthpiece end and open on the bell end.

6. But obviously that "rule" doesn't work for playing the second partial, otherwise the second partial would not resonate and be playable.

7. I don't know this, but my suspicion is that much of the arm-waving that goes on about how a tube is characterized is based on what others have written in the context of playing fundamentals.

8. I do know this: When calculating the wavelength and therefore the nodes and antinodes in free air, one must know the frequencies (including those of the overtones), the speed of sound, and make an assumption of air density (which is affected by altitude, atmospheric pressure, and temperature).

Rick "that is what I know, and what I suspect" Denney

[imperialbari]

If those O-rings are intuitive, they may be worth their price.

K

[Allen]

... ...
1. Nodes occur at the lips, and in whole wavelengths downstream from that point.

2. Antinodes are halfway between nodes, approximately (the approximate part is because of the taper).

3. The wavelength is what it is to produce the note in question. So, if an instrument playes a fundamental 26-Hz pedal Bb, the next node will be 43ish feet away from the mouthpiece. If that isn't the case, it won't be a 26-Hz Bb.

4. If an instrument plays a 58-Hz second-partial Bb, then the next node will be 21ish feet from the mouthpiece, which is a bit outside the bell. Obviously, the node is at (or near) the bell when playing the second partial, and the antinode is at (or near) the bell when playing the fundamental. I see no alternative from a physical point of view.
... ...

Rick, I think you slipped on one fundamental point: The nodes are a half-wavelength apart, not a whole wavelength.

This is why a cylindrical organ pipe (open at both ends) can have a length of 16 feet (a half wavelength) for the C at 32 Hz. There is an antinode at each end. If we stop one end of the pipe, it is now a quarter-wave resonator, and that 16 foot long pipe will sound the C at 16 Hz (assuming the pipe builder has got things voiced well for that lower pitch).

Tubas are more complicated, as we know. A BBb tuba with an open bugle length of about 18 feet has no resonance at all at the pedal Bb (29 Hz). We can play that pitch because of all of the tuba's other resonances that coincide with harmonics of that note. The real bottom resonant frequency is about 39 Hz (Eb), known as the false tone. This bottom resonance is broad and poorly reinforced, as few of the other resonances of the instrument coincide with harmonics of that note.

The first good resonance of a tuba is what we call the second partial (in the case of a BBb tuba, 58 Hz, or Bb). I know there is a node at the mouthpiece, and an antinode somewhere in the vicinity of the bell. How many other nodes and antinodes there are in-between (I guess one each), and exactly where they are is something we all would like to know, for this note and all of the other notes too. This would be a great research topic. After it's published, we will know where to aim our hammers!

Cheers,
Allen

[MikeMason]

Sometimes i long for the good ole days.If we observed a phenomenon we couldn't explain,we just chalked it up to "magic" and got on with our lives(which were only around 35 years because we didn't believe in germs)

[sloan]

Sometimes i long for the good ole days.If we observed a phenomenon we couldn't explain,we just chalked it up to "magic" and got on with our lives(which were only around 35 years because we didn't believe in germs)

So...if the low C is weak on you F, the solution is to bleed it?

[tubatom91]

Sometimes i long for the good ole days.If we observed a phenomenon we couldn't explain,we just chalked it up to "magic" and got on with our lives(which were only around 35 years because we didn't believe in germs)

So...if the low C is weak on you F, the solution is to bleed it?

Leeches... just stick 'em on and let her rip. perhaps you could add them to the mouthpiece for extra mass or somthing

[sloan]

Sometimes i long for the good ole days.If we observed a phenomenon we couldn't explain,we just chalked it up to "magic" and got on with our lives(which were only around 35 years because we didn't believe in germs)

So...if the low C is weak on you F, the solution is to bleed it?

Leeches... just stick 'em on and let her rip. perhaps you could add them to the mouthpiece for extra mass or somthing

Do you attach the leeches at the nodes, or the anti-nodes?

[ztuba]

You guys are awesome!

[jtuba]

My young self could not for the life of my figure out how to play the low C on any rotary F tuba I played. Now I have two rotor Fs that I don't have a problem with, a new school and old school intrument that rock down there. The first time I played a Miraphone 180 I put it down right away, the next time I played a 180 at Dillon music two years ago, I didn't want to put it down. Sure some instruments work better than others, but I've learned not to be so heavy handed as I was as a younger player. As a result, I'm less inclined to think it's a design issue, and I'm all for using hardware to solve software issues