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Thanks a lot for the replies, Matt. Will do. I should ask Peter too. A lot of thought and trial went into the design of the bore of his horn so I am pretty sure it is me or something trivial.
 

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jbtsax said:
Let's see, a compressed cork that no longer has the right adjustment does not need replacement just a band aid. Hmmm. I'm glad you don't work on any of my instruments. :)

A Concerned Tech
Actually, teflon tape as the outer layer on the neck cork is more of an improvement than a bandaid. It seals perfectly and is capable of being adjusted in seconds should the need arise. :p

(don't get your knickers in a knot here- THIS one actually does have some merit unlike congealed superglue as a structural member......)
 

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brasscane said:
1. I don't understand "somehow". Is the implication that the mouthpiece is "rocking" on the cork and that causes the gurgle?

2. A repairman pointed out to me that a good neck cork is tapered and fat at the end so the end of the mouthpiece pushes against it. Is this because it prevents gurgling? (In that case neck corks out to be longer on alto necks.)
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If the cork at the open end of the tenon is slightly smaller diameter than the bore that it encounters in the mouthpiece, then this is most definitely a likely source of burbling, no matter how well the rest of the cork seals.

Both this and a leak between the neck and body can have quite dramatic acoustic effects, including buzzy noises at the upper end of the second octave.

On a soprano especially, and on some sax models more than others, burbling is also induced by the mouthpiece not being pressed on far enough. Try it.
 

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Actually had the good fortune to study acoustics as an undergraduate with Prof. Bose (yes, the speaker guy).

Musical instruments are mostly about standing waves with places where the pressure oscillates higher and lower separated by 'nodes' where theoretically the pressure does not oscillate or remains 'grounded'. This is assuming perfectly rigid container and a single mode (i.e. frequency or wavelength). Musical instruments in general are imperfect containers, having all sorts of lossy materials (cork and pads, which create partial nodes that reduce but don't 'ground' the oscillations) and artificially imposed nodes (leaks).

In an acoustic system, just like in any waveguided system, anything that branches out from the main bore creates a cul-de-sac of sorts that has a tuning of it's own. Tonehole chimneys are sort of like that, register keys are very much on this principle, to create a node that is operative at some wavelengths and not at others...i.e. tuned. My hunch is that the neck cork leak is some type of shunt that seems to hit right at the bell key frequencies...I have seen it at C# as well. Since I first discovered this, I have fitted neck corks by making them thinner at the farthest from the end of the neck first and then sanding right at the end to get a good fit. On my own horns I have turned little metal pieces (some replacements for existing, some new) and soldered them on...don't remember what folks call these, but the ones I make I fit just ever so slightly undersized so the air column sees metal. I have even experimented with tapered extensions, but can't convince myself that it helps.

The one thing that I can't figure out, though, is that the wavelengths involved are to short...For example, the wavelength of middle C in air is about 4 feet, and a quarter wavelength (for a tuned stub) is still about 1 foot. If something that is a centimeter (1/30 of a foot) is to have an effect, it would be at a fundamental frequency about 5 octaves higher than middle C.

....what am I missing???
 

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Don’t know where else to ask this. I have a white brilhardt tonalin tenor mouthpiece 5*. I love the sound it gets but the low notes I can only get out with a sub tone. If I try to put more air in the instrument to get them out normally it just shoots up an octave.
 

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selmer 26 nino, 22 curved sop, super alto, King Super 20 and Martin tenors, Stowasser tartogatos
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Don't know where else to ask this. I have a white brilhardt tonalin tenor mouthpiece 5*. I love the sound it gets but the low notes I can only get out with a sub tone. If I try to put more air in the instrument to get them out normally it just shoots up an octave.
If your other mpcs allow good response in the low notes, I would first check if you have a leak at the neck cork. Mpc throat diameters are not standard, so the Brilhardt might be a bit larger and thus not seal well. A narrow chamber will tend to disfavor low notes, but they should sound. Also check the seal of the reed. If the table is warped it might cause a leak. Close the end of the mpc with the palm of your hand and suck the air out to create a partial vacuum. It should hold for a least a half a second or so before popping open.
 

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In another thread, @saxoclese attached Benade's course notes and pointed to page 65 (in, by some incredible coincidence, post #65 in the thread...) What makes one saxophone more "free blowing&quot.... Extremely helpful!

One point that caught my eye is that in Benade's woodwind joint diagram, a narrow gap ("A" in his picture) of < 0.1mm would be considered a very efficient "eater of energy". That configuration is really close to an imperfectly fitting neck cork.

Also, the suggestion "push in the mouthpiece and lip down" given in many other threads on the topic of warbling could actually simply have the effect to reduce or eliminate any gap between neck cork and mouthpiece bore - while tuning the horn unbearably sharp as a side effect, of course...

To me, the observations of (a) successfully addressing burbling by improving neck cork fit and (b) "fixing" burbling/warbling by pushing in the mouthpiece and (c) Benade's equivalence between a very narrow (<0.1mm) gap and a leak-like behavior look very consistent.
 

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In another thread, @saxoclese attached Benade's course notes and pointed to page 65 (in, by some incredible coincidence, post #65 in the thread...) What makes one saxophone more "free blowing&quot.... Extremely helpful!

One point that caught my eye is that in Benade's woodwind joint diagram, a narrow gap ("A" in his picture) of < 0.1mm would be considered a very efficient "eater of energy". That configuration is really close to an imperfectly fitting neck cork.

Also, the suggestion "push in the mouthpiece and lip down" given in many other threads on the topic of warbling could actually simply have the effect to reduce or eliminate any gap between neck cork and mouthpiece bore - while tuning the horn unbearably sharp as a side effect, of course...

To me, the observations of (a) successfully addressing burbling by improving neck cork fit and (b) "fixing" burbling/warbling by pushing in the mouthpiece and (c) Benade's equivalence between a very narrow (<0.1mm) gap and a leak-like behavior look very consistent.
My feeling is probably not. It would not manifest only on the lowest couple of notes. Anyway, and easy way to test is to put some wraps of teflon tape to seal the neck cork efficiently. If you read Benade, you will find that all conical woodwinds suffer from a major deficiency, and that is that with the lowest notes, the second partial peak is almost as strong as the fundamental (sometimes stronger). That is one of the reasons it is hard to play the lowest notes softly, because it has a tendency to break to the octave. But there is another phenomenon that can happen when two impedance peaks compete like this, which needs to be understood when looking at low note burbling or motorboating.

There is a phenomenon known as mode locking, which means that for a note to be sustained, all partials have to line up in perfect integral alignment. If you play A at 440 Hz, then the second partial will always be at exactly 880, the third at 1320 Hz, the fourth at 1760 Hz, etc. In an ideal bore shape, impedances will exist at exactly those points in the bore, in which case the fundamental excites the second, third, fourth partial impedances and they all contribute their fullest to the sound. However, bores are never ideal. In the real world, impedances might exist at 440, 870, 1350 and 1720. Those are the points where the air column wants to vibrate, but they are not lined up exactly. For the note to sound, they have to be lined up exactly. Something has to give.

Benade says that there is a "regime of oscillation". In this example, the 2nd partial wants to pull the standing wave down to where its center is--here it would like the fundamental to be 435 Hz. The 3rd partial wants to pull the tone up to center at 450 Hz, and the 4th would like the tone to center at 430 Hz. So a negotiation happens, in which each partial gets a "vote" corresponding to its strength. Generally, the fundamental first partial is much stronger than the other partials, so it has the most "pulling power". The higher partials generally are much weaker, so they tend not to be able to influence the pitch much. In this case, the third and fourth partials probably don't have much say, but the second partial has a bit of influence, so it may end up being able to influence the pitch a bit, pulling it slightly down.

As a side note, when a partial is pulled off its center, it loses some strength, which is why a horn with a poor bore profile often sounds rather muted and is unresponsive, because the higher partials have lost a lot of strength (if their impedances are way out of alignment) and all the partials are somewhat being pulled away from their strong points and fighting each other for control, even though the strongest partial is going to win overall.

Now let's go back to the case of the low notes on a conical woodwind, where the first and second impedance peaks are almost the same strength. If the bore is well designed, and the first and seconSd impedances are nearly in mathematical alignment, all is well, but if they are misaligned big trouble can result, as a tug of war happens over the pitch center. Let's take the case of low B on the tenor, which is actually 110 Hz. Let's say that the lowest impedance peak for that fingering is 110 Hz, but that the second impedance peak in the horn is not 220 Hz as it should be, but instead is 228 Hz. The first partial is pulling for the note to be sounded at 110 Hz, where it is strongest, whereas the 2nd partial is trying to pull it up to 114 Hz, where it is strongest as a second multiple. It would seem that they would settle somewhere around 112 Hz if they are equally strong, but there is something else at play, which is that higher partials become stronger as dynamic is increased. So subtoning, you might be OK, with the lowest partial determining the frequency, but as you increase the dynamic, the influence of the 2nd partial becomes stronger, until it equals that of the fundamental, at which point, the lead passes between them and destablizes the note. Dropping a cork or some wax in the bottom of the bow sometimes solves this by slightly changing the impedances, so that they are more in alignment.

It is certainly possible that leaks here or there, or bore incontinuities such as Benade describes, can have an effect on impedances that would exacerbate the problem, but it is the problem of bore design and the fact of the weak fundamental peak in the lowest notes of conical woodwinds that is the main cause of the problem. If a small extra compliance caused by an ill-fitting cork triggers the problem, it is still not its primary cause.
 
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