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Interestingly enough I have a YAS 23 that has either a low C or D warble. It is six years old and had a total of maybe eight hours on it. I knew the student who purchased it new and after a month quit. So basically it's a brand new OE Sax. Took it to tech for once over and we had nasty warble down low on his ?? Bench MPC. Will find out what MPC/reed# he uses. We changed one pad, no go! Tossed some junk Mouthpiece cover into it went away. Changed other pad, no go. Grabbed Yamaha 4c MPC from case...no go! #3 reed changed to #2 (from case) bang! That did it?. Took it home and it all came back. Fix didn't last an hour. And that's all matching OE factory gear with the exception of the Reed. Just a cheerful student Yamaha. Haven't touched it since last August. Just put it back in the case and move on. Due to recent surgery I can't play for another week. when I can I'll let you know. Now I'm curious
Info from sax tech man. Mouthpiece used at the time was Ted Klum with #3 Vandoren reed. Couldn't remember the exact specs of the mouthpiece. He hasn't used it Lately and we couldn't find it.
 

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John, having looked at some research, my thinking is that warble would probably be caused by the combination of weakened fundamental + bore inharmonicity, and such a combination can be caused by, for example, a leak.

First look at the impedance chart with and without a register (octave) key used. The octave key weakens the fundamental, of course, and also tunes it upwards. Now, imagine one has a slight leak at the neck tenon or in the upper stack. The effect would be somewhere in between the curves of the chart. And, if the fundamental and 1st overtone become roughly equally strong, AND since they are now not exactly in tune, that would result in an oscillation/beating regime.

Slope Organism Font Rectangle Line


(Chart from:
SAXOPHONE ACOUSTICS: INTRODUCING A COMPENDIUM OF IMPEDANCE AND SOUND SPECTRA
Jer-Ming Chen, John Smith and Joe Wolfe)

In addition, some interesting experiments have been done recently, although with a different way to generate the inharmonicity, see the paper below.

To me, the results seem to provide at least a partial explanation of the warble phenomenon. In a leak-free saxophone, I guess it is rather unlikely that the fundamental is weaker than the overtone. Once the fundamental is weakened, the complete air column of the instrument including mouthpiece volume, mpc placement and reed stiffness will probably play a role in determining whether or not the oscillation is triggered.

Jean-Baptiste Doc, Christophe Vergez. Oscillation regimes produced by an alto saxophone: Influence of the control parameters and the bore inharmonicity. Journal of the Acoustical Society of America, Acoustical Society of America, 2015, 137 (4), pp.1756. <10.1121/1.4916197>. <hal-01229842>

https://hal.archives-ouvertes.fr/hal-01229842/document
 

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Discussion Starter · #23 ·
Thanks for that link. It will take me a while to read and digest the information. Unfortunately it is true that on the lowest 4 notes of the saxophone the fundamental is the weakest. It does not require any leaks. If I remember correctly it is because being so close to the bell opening the resonance of the lower portion of the tube is not as strong, but I will have to look that up.
 

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John, having looked at some research, my thinking is that warble would probably be caused by the combination of weakened fundamental + bore inharmonicity, and such a combination can be caused by, for example, a leak.

<snip>

To me, the results seem to provide at least a partial explanation of the warble phenomenon. In a leak-free saxophone, I guess it is rather unlikely that the fundamental is weaker than the overtone. <snip>
You are assuming that the low note warble is caused by leaks. This is the standard assumption, but there are two problems with that:

1) Some years ago I had a Conn 10M that had a bad warble on most notes below about low F. In testing, I closed every tone hole above the one being tested with duct tape, taped over both octave vents, and taped carefully all around the tenon/receiver joint. With all this the problem remained. It didn't even get better.

2) Of course, in actual practice no saxophone is completely leak-free; certainly not after a few hours have passed since it left the technician's bench. Yet it is anecdotally clear that some models of saxophone have this problem much worse than others. I suppose one could argue that those particular models are also prone to leaks at a location that acts as a vent. Except for item (1) above.

I personally believe that there is something about the bore and tonehole design of certain instruments that makes the lower notes inherently unstable. I further believe the Conn 10M is a particularly bad example of this, based on personal experience and anecdotal reports from a large number of people.
 

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One thing occurs to me: the poster child for low note warble, the Conn 10M, has (I believe) a larger radius to the bottom bow than other saxophones. It might be interesting to see whether warble correlates with models of saxophone that have a larger radius bottom bow (Keilwerth, Buescher 400, Conn?)
 

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You are assuming that the low note warble is caused by leaks. This is the standard assumption, but there are two problems with that:

1) Some years ago I had a Conn 10M that had a bad warble on most notes below about low F. In testing, I closed every tone hole above the one being tested with duct tape, taped over both octave vents, and taped carefully all around the tenon/receiver joint. With all this the problem remained. It didn't even get better.

2) Of course, in actual practice no saxophone is completely leak-free; certainly not after a few hours have passed since it left the technician's bench. Yet it is anecdotally clear that some models of saxophone have this problem much worse than others. I suppose one could argue that those particular models are also prone to leaks at a location that acts as a vent. Except for item (1) above.

I personally believe that there is something about the bore and tonehole design of certain instruments that makes the lower notes inherently unstable. I further believe the Conn 10M is a particularly bad example of this, based on personal experience and anecdotal reports from a large number of people.
Well, that horn must have driven you nuts to go as far as you did with duct tape! I have never played a 10M.

Anyway, what I said (or intended to say) is that my hypothesis is that warble is caused by the combination of a weak fundamental and out-of-tune octaves (inharmonicity). Leaks obviously push both factors in the wrong direction, but with the sax described for the paper, a special neck was used to create different levels of inharmonicity, (supposedly) WITHOUT the sax leaking.

Note that the neck taper is apparently very important for the inharmonicity. Ninob (see the French link) measured a... wait... Conn 10M tenor, and found that the neck taper was incorrect: too large to be able to get the horn in tune. He applied some epoxy in the neck to correct the taper. Obviously, if your horn's problem started around F, then the neck is a more plausible root cause than the bow.

Another factor which I think could determine the warble threshold is the width of the resonance peaks. It is my understanding that this width is lower for the low notes (i.e. less flexible, less bending possible). In the paper they found delta f / f = 106% for G "warble" to start and delta f / f = 103% for C "warble". 3% between the octaves corresponds to roughly 50 cts, and it is certainly possible - although not desirable - to have a note +25 cts in one octave, and -25cts in the other octave ... as determined by body design, mouthpiece placement, etc. And, as a function of the design, it may be impossible to have in-tune octaves, and an overall matching with A=440Hz or 442Hz, at the same time.

There is another interesting study here https://hal.archives-ouvertes.fr/hal-01087013/document
 

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Discussion Starter · #27 ·
Dirk. Thank you for that input and the link to the study. We share the same hypothesis as to the cause of the warble. This is a link to a video presentation I made showing the "battle" of the overtones that are out of tune with one another to take over the "regime of oscillation" as Benade calls it. The warble was created on a C-melody saxophone playing low C. It was recorded and put into slow motion. Snapshots of the spectograph was made at several fractions of a second and then put together like drawings in a cartoon and then sped up to give the motion in time. A stronger fundamental would make them behave and get in line with its own pitch, but being without power it is helpless.

[video]https://vimeo.com/home/myvideos[/video]
 

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This is an example of the type of recording I am looking for:

C Melody Warble

This is the warble in slow motion:

Warble Slow
See post #21. I'm back playing some...took beast out today and tried everything to get some kind of wonky warble puff or failure. Dang alto fixed it self No clue it's just stupid. Yam 4c & some orange box Rico 2-1/2 had in pile.
 

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One thing occurs to me: the poster child for low note warble, the Conn 10M, has (I believe) a larger radius to the bottom bow than other saxophones. It might be interesting to see whether warble correlates with models of saxophone that have a larger radius bottom bow (Keilwerth, Buescher 400, Conn?)
My Couf (Made by Keilwerth) has no warble issue. Had one previously on a Big B I had for a short while, the side Bb key was being blown open as I played to cause the warble on D
 

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Well, I have had this problem with a couple of saxes over the years. An Adolphe Sax/Selmer alto motorboated on low C, I took it to Jack FInucane at Boston Sax Shop who replaced the side C spring to increase the tension. It was leaking when the horn was played. Cured.

My Conn Bb soprano 25154, just overhauled at Virtuosity Music in Boston, motorboated on C like crazy. Another player had no trouble. Very diligent study showed no leaks. I even found a way to play the horn with a light in it, placing tin foil in the bow and shining a light in the bell, to show that there was no leak--none--at play. Not on the side keys, not in the palm keys, nowhere.

Putting the mouthpiece waaaaay in and using a large chamber piece helped but did not eliminate the motorboating. So I figured it's an acoustic problem, we have to take energy out of the upper overtones. A piece of wine cork in the bow worked fine but had to be so large as to make low D really flat. So I cut a rectangle of 1/8 inch sheet cork, 1 3/4 x 2 3/4 inches. I stuffed it into the bell and with the C key removed, used a chop stick to push it and position it between the E-flat, C and C# toneholes on the inner aspect of the bore on the left side. This removed as much volume from the bore as the champagne cork fragment had but without obstructing the C key and making D play flat. The tension of the cork sheet holds it in place.

Now I can use any mouthpiece and there is no motorboating. Problem solved.

Another commentator on a similar thread mentioned the work of physicist Arthur Benade and used his analysis to address this issue. I took his storied "Acoustical evolution of woodwind instruments" seminar in Fall 1977, he discussed this trick then. I have used a mouthpiece cap or a champagne cork many a time over the years. This is the first time I have ever fitted a prosthesis, but it looks like a good solution. Took me about 30 minutes, most of it spent putting the C key back on.

View down bell. Bb to top right. Cork at bottom just past C# tone hole

9824


View into bore of body thru C key. Eb is out of view on left at 7:00. Rear Eb is at 9:00. Cork has cracked on its leading edge.

9826


View into C key tone hole (which vents D). Saxophone body to left, bell to right. Cork edges on tone hole.

9827


View into bore of bell through C key's hole. Cork on edge of C# tone hole.

9829


Any of your repair guys who use this trick, please send me a tenner. You're welcome!
Robert Howe, Wilbraham MA
 
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