Sax on the Web Forum banner
Status
Not open for further replies.
1 - 20 of 40 Posts

·
Banned
Joined
·
5,336 Posts
Discussion Starter · #1 ·
A big deal seems to be made about saxophone necks that have experienced "pull down" and have become slightly oval at the area of the bend. This raises the question of whether there is has been any type of study to determine the acoustical effects of making all or part of a conical tube of a musical instrument out of round.

My firsthand experience as a former band teacher was that there were many school brass instruments with slightly flattened or oval tubing that seemed to play reasonably well. Oftentimes the cost of removing all of the hard to get to dents exceeded the value of the instrument so limited budgets trumped the desire to have all instruments cosmetically look their best.

So, are there measurable effects of a slightly oval neck on a saxophone in terms of intonation or tone quality, or does that fall into the same category as "if the sax is re-lacquered it can't possibly play as well"?
 

·
Banned
Joined
·
2,042 Posts
Given that the cross sectional area of a 1 inch internal diameter neck is .5 * 3.14 and the cross sectional area of a 1.08x .9 inch moderately ovalized neck is .55 * .45 * 3.14, the resultant cross sectional areas of .78 vs .763 square inches means a difference of about 2.8%.

This is pretty severe "ovalization" yet seems unlikely to have a profound effect even on the notes whose pressure node falls into the ovalized area.

Probably noticeable in an A/B and perhaps perceived as mildly squirrelly but not acoustically earth shattering.

Lesser distortion, as is normally the case with perceptible but moderate pull down, would have a lesser difference of course.

I know of no formal study but know of many horns with detectable pull down and detectably oval tubing as a result that play fine.

After you finally get disgusted with the TT neck you might test it one last time against the tuner, then bend it down and see if it flattens out those A's and above as a side effect! Moral satisfaction at least...
 

·
Distinguished SOTW Member
selmer 26 nino, 22 curved sop, super alto, King Super 20 and Martin tenors, Stowasser tartogatos
Joined
·
3,402 Posts
In my understanding, if the volume of the ovalized area remains the same there should be little if any acoustic effect. Severe distortion might be another matter, of course. That being said, if the bore at the point of distortion has the volume reduced, that could affect intonation and/or timbre, depending on what notes or harmonics have antinodes in the area. This is predictable by Rayleigh perturbation theory, I would think.

Another point to consider is that an ovalized tube has lowered resonance frequencies, which could conceivably result in increased vibration of the walls having an effect on tone color of certain notes. In reality, though, the walls are normally thick enough that this shouldn't be a consideration in sax necks.
 

·
Distinguished SOTW Member/Forum Contributor 2009
Joined
·
4,507 Posts
In my understanding, if the volume of the ovalized area remains the same there should be little if any acoustic effect. Severe distortion might be another matter, of course. That being said, if the bore at the point of distortion has the volume reduced, that could affect intonation and/or timbre, depending on what notes or harmonics have antinodes in the area. This is predictable by Rayleigh perturbation theory, I would think.

Another point to consider is that an ovalized tube has lowered resonance frequencies, which could conceivably result in increased vibration of the walls having an effect on tone color of certain notes. In reality, though, the walls are normally thick enough that this shouldn't be a consideration in sax necks.
how 'bout a neck that has been sanded to be perceived as "perfect" after a refinish? Wouldn't uneven mass removal be an issue that maybe coupled with wrong octave pip, diameter distortion and bend crush cause a lot of intonational challenges?
 

·
Banned
Joined
·
5,336 Posts
Discussion Starter · #5 ·
I have always held the assumption that a perfect circle when converted to an ellipse keeping the same perimeter/circumference would have the same area. However upon doing some preliminary research I have found this to be an amazingly complex area of mathematics. It would seem to me with my current level of understanding that if the interior volume of the tube remains unchanged in the "ovalled" section that the effect upon the sound wave would be minimal if not imperceptible.

I hope this thread helps jicaino learn that changes in the outside wall surface of a thick walled woodwind have no effect whatsoever on the soundwave inside the tube.
 

·
Distinguished SOTW Member/Forum Contributor 2009
Joined
·
4,507 Posts
I have always held the assumption that a perfect circle when converted to an ellipse keeping the same perimeter/circumference would have the same area. However upon doing some preliminary research I have found this to be an amazingly complex area of mathematics. It would seem to me with my current level of understanding that if the interior volume of the tube remains unchanged in the "ovalled" section that the effect upon the sound wave would be minimal if not imperceptible.
obviously your math is wrong or your horns won't get returned

I hope this thread helps jicaino learn that changes in the outside wall surface of a thick walled woodwind have no effect whatsoever on the soundwave inside the tube.
I hope that the return of "you wont find another as nice" e-bay true tone fiasco makes you realize that

A) it's not OK to fiddle with things and not disclose that to your customers
B) it's not OK to raise your moral pedestal by attacking other individuals and then fail in the same way you used to attacked them in the first place
C) you're not a neck taper expert
D) you're not a "professional" repairman
E) karma's gonna get you
F) reading a bunch of articles written by courtney alterneck does not makes you an expert in anything but parroting non firsthand knowledge/experience
 

·
Distinguished SOTW Member/Technician
Joined
·
4,702 Posts
Can someone get the lights.:popcorn:
Shows about to start
 

·
Distinguished SOTW Member, Forum Contributor 2014
Joined
·
2,355 Posts
Don't exactly know what's going on here but to stay on topic. I don't think a slight
" ovalization" of the neck is a problem is sound or intonation. My Selmer neck is slightly oval and it's the best playing mark VI i have come across in 24 years. I did playtest dozens, some of them with more and others with less pull down. Could not identify that as a problem on any mark VI.
But I guess I would mention it in case I ever tried to sell it ( which I won't) :twisted:
 

·
Banned
Joined
·
5,336 Posts
Discussion Starter · #14 ·
There are many beliefs about saxophones that have only anecdotal support and no solid scientific evidence that they are in fact true. Among these I would include:

- A relacquered saxophone does not sound as good or play as well as one that has not been relacquered.
- A soldered bell body connection plays the low notes better than an epoxied connection.
- Metal resonators produce a brighter sound and more volume than plastic resonators of the same dimensions.
- Being pulled down causes a neck to play poorly and out of tune.

I'm not trying to broaden the topic of this thread, but merely put the question in the proper perspective.

The essential questions that perhaps those with a greater understanding of mathematics can answer are:

1. When a circle is made slightly elliptical, does the interior area change?
2. When a circle is made slightly elliptical, does the perimeter (circumference) change?
3. When a round frustum (truncated cone) is made slightly elliptical, does the volume change?
4. What effect does starting in a round tapered tube and then passing through a slightly elliptical tube have on a sound wave?

Benade writes that when the sound wave goes around a sharp bend in the tubing, it "sees" a larger tube in that area. If that bend not only changes direction, but shape inside what effect does that have on what the sound wave "sees" as it passes through?
 

·
Banned
Joined
·
2,042 Posts
I have always held the assumption that a perfect circle when converted to an ellipse keeping the same perimeter/circumference would have the same area. However upon doing some preliminary research I have found this to be an amazingly complex area of mathematics.
The calculation of the perimeter of an ellipse is truly a very knotty bit of mathmatics- there are simple approximations and very complex closer approximations. Absent stretching of the brass (unlikely to any significant extent in a simple pull down and which would result in an enlarged neck when it was bent back into round) the perimeter is probably pretty much unchanged when the circular cross section of the brass tube is deformed.

The area is, on the other hand, pretty easily calculated to a very, very, close approximation; Area = Pi * A * B where A and B are the minor axes. The axes as a circle and as a fully flattened ellipse are known- the ones inbetween are hell on wheels to calculate precisely. A given reduction in the vertical axis results in an increase in the lateral axis- but the increase is less than the vertical axis decrease.

Figure as you will; ovalizing a circle (retaining the same perimeter) reduces the area- ultimately to zero. This is clearly established geometry- nothing arguable. A fully squished neck- represented on EBay as, "Needs some work; your local music store can fix this easily."- with a starting diameter of one and hence a perimeter of about 3.14 will have minor axes of .785 and zero- and an area of zero. The function from the starting area of 1.57 (1/2 * 3.14) for a perfect circle to zero is a non linear one- the reduction in area accelerates as the squish is increased with very little difference at the start and a exponentially increasing discrepancy as the circle is completely ovaled down to flat.

How much effect the reduced cross sectional area will have depends of course on what pressure nodes fall into the affected area and how great the ovalization/ reduction is.

Effect on the sound wave and interaction with the "bend" in the ovalized area is a separate and less well understood area.
 

·
Distinguished SOTW Technician
Joined
·
3,410 Posts
Oval saxes--thats the way to go! All our dent balls will need to be 'ovalated' then! Really think this is becoming a p-ss-ng contest.
I've had necks in and seen guy's playing on necks with all manner of dents, pull downs you name it--no difference to tone or sound whatsoever.
 

·
Banned
Joined
·
2,042 Posts
the math may be right and can be done. But can we hear a difference ?
Based upon average replacement costs for name brand sax's that is indeed the "three hundred and twenty dollar question."

For vintage horns it's just out there as something else to obsess over.

Squished I've got. Slight pull down? Heck- IMHO it ranges from imperceptible change (perhaps none at all for virtually all intents and purposes) to very slightly different. That "different" being impossible to pin down to just the neck in the first place and maybe worse, maybe better, maybe just not quite the same.
 

·
Distinguished SOTW Member
selmer 26 nino, 22 curved sop, super alto, King Super 20 and Martin tenors, Stowasser tartogatos
Joined
·
3,402 Posts
how 'bout a neck that has been sanded to be perceived as "perfect" after a refinish? Wouldn't uneven mass removal be an issue that maybe coupled with wrong octave pip, diameter distortion and bend crush cause a lot of intonational challenges?
Wrong pip dimensions or placement wouldn't be different in a pulled-down vs. normal neck, so the effect wouldn't change. Change in cross-sectional area could have an effect, concievably. Change in angle is much too small to matter, and mass removal would not even begin to enter the picture until wall thickness is reduced by a factor of five or more, according to research done by Gilbert.
 

·
Distinguished SOTW Member/Forum Contributor 2009
Joined
·
4,507 Posts
Wrong pip dimensions or placement wouldn't be different in a pulled-down vs. normal neck, so the effect wouldn't change. Change in cross-sectional area could have an effect, concievably. Change in angle is much too small to matter, and mass removal would not even begin to enter the picture until wall thickness is reduced by a factor of five or more, according to research done by Gilbert.
I understand that a minor ovalization of the section is not a big deal per se. That minor octave pip diameter and shape changes are not a big deal per se. That careful mass reduction if absolutely necessary are not a big deal per se.

The OP started this thread with the hidden purpose of validating his work on a neck. As the story goes, he worked on and replated a Buescher True Tone neck. He pushed it as original on the ad selling the horn, but then started to moan about how Buescher altos cannot be made to play in tune, upper register sharpness, and started to describe everything he did to the neck in question. Octave pip fiddling, rolling out dents and then sanding to achieve a perfect surface look and then replate, so and so. All taht without experience in the make and model. His debut with Bueschers was made on this horn, and his subsequent comments were to the effect that Bueschers should be avoided because they don't play in tune. He plotted a chart of measures for a Selmer Balanced Action alto neck wich he indicated "cleared the intonation to some extent" so I think he tried reshaping parts of the Buescher neck to closely resemble the shape of the BA's neck.

My concern is to serve this person the validation he needs on a silver plate (pun intended). Not because he reformed the neck, but because after fiddling a lot with a neck (so heavily that it required replate) he wasn't upfront with the SOTW community when he tried to sell the horn here and on eBay. :tsk:

The list of issues he describes (sharp upper register avobe A2 and such, and other long tube/short tube coherence issues) are in my opinion due to the fact that the opened (enlargened the section) between the port and the octave pip, he mistweaked the octave pip shape and vent diameter, didn't repair the pulldown at the bend properly and a combination of them factors.

This would be my last post in this thread, but please, keep in mind this: all your contributions here are only going to be read as favorable/opposed to what's he's claiming, be that true tones cannot play in tune and or altering a neck in such an involved way is something "minor" that it's OK not to disclose, or that all the reshaping/fiddling he did with the neck is something that cannot be a part of how bad that horn plays now (eBay buyer returned the horn)

EBAY Auction link
http://cgi.ebay.com/ws/eBayISAPI.dl...zTbw9m9CDY%2FTULc%3D&viewitem=#ht_1426wt_1140

SOTW activity reflecting "neck quests", "bead blasting" and "neck retapering" references from the same individual... (I know there's one thread referring to Doc Frazier too, just don't want to use my entire sunday on this one)

http://forum.saxontheweb.net/showthread.php?158918-Fs-Buescher-True-Tone-Alto
http://forum.saxontheweb.net/showthread.php?157614-Help-With-Summer-Buescher-TT-Project
http://forum.saxontheweb.net/showthread.php?159016-Slightly-Squished-Neck
http://forum.saxontheweb.net/showthread.php?159193-need-advice-on-buying-an-alto-saxophone/page2
http://forum.saxontheweb.net/showthread.php?160443-True-Tone-Alto-Neck-Question
http://forum.saxontheweb.net/showth...her-True-Tone-Alto-Please-confirm-date./page2
http://forum.saxontheweb.net/showthread.php?160331-Mark-Aronson
http://forum.saxontheweb.net/showthread.php?160437-A-question-for-the-machinists
http://forum.saxontheweb.net/showthread.php?159670-Bead-Blasting-101
http://forum.saxontheweb.net/showthread.php?160528-Neck-Pull-Down
 
1 - 20 of 40 Posts
Status
Not open for further replies.
Top