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Distinguished Technician & SOTW Columnist. RIP, Yo
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Yes, I think Reynolds number would have a lot to do with it.
It attempts to determine when laminar (efficient) fluid flow transitions to turbulent (inefficient) flow.
A higher number means turbulent flow.

See "Flow in a pipe" at https://en.wikipedia.org/wiki/Reynolds_number#Flow_in_a_pipe
Seeing Reynold's Number is proportional to diameter, we can reduce it by turning one large tube into several smaller tubes, using pantyhose.
It's a bit counter-intuitive because by covering with pantyhose we might think we were reducing the flow, but by keeping the flow laminar it is more efficient and that "trumps" the reduction.

Chamfering the sharp edge at the ends of the vent tube can also reduce turbulence.

For an excellent demonstration of how turbulent flow is much slower, turn on a garden hole with a squirter on the end. Not gradually kink the hose. At one point the laminar flow in the hose suddenly changes to turbulent (because of the localised constriction/sharp bend). The squirt from the jet is dramatically reduced (indicating reduced flow, and we can hear all the turbulence occuring at the kink.

(I hope I have got this right; it's been 25 years since I studied it.)

Do the thrusters of rockets have divided orifices, eg multiple tubes? If so I guess it is the same pantyhose syndrome.
 

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The flow in the area of the pip is so short, that the air will not be able to achieve a fully developed flow profile, so applying fully developed profile Reynolds numbers does not make much sense. Laminar and turbulent pipe flow models should probably be discarded for this phenomenon. However, if you did, you would find that the flow would be much lower than expected for fully developed turbulent flow in a pipe. Again, the key is the phrase fully developed.
Entry and exit flow conditions can however, create flow separations within, and exit eddies at the pip. It could be that the small mesh of the panty hose simply breaks up a large eddy, or possibly redistributes the air more uniformly across the exit orifice of the pip.

Now that I too have overthought the issue, all that really matters is if the panty hose eliminates the hiss, which according to many reports, happens.
 

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Distinguished Technician & SOTW Columnist. RIP, Yo
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By doing something that improves D/D# you may make G/G# worse in some respect, seeing they use the pip at the other extreme of its compromises.
 

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I would imagine that the pip didn't hiss when the instrument was manufactured, so I would only try "major surgery" as a last resort. I had a similar problem on the neck of an alto, and it turned out to be a layer of "crud" that had built up and dried in the pip, changing the air flow. I would recommend (1) that you follow the advice of Nefertiti: "Make sure you try cleaning out the pip also just in case there is stuff clogging it up partially," and (2) check the pad to make sure the surface of the pad is sound and not loose. On my alto, I first tried to clean it with a pipe cleaner, but that didn't do much because the deposited crud layer had dried. I inserted the tip of a small screw driver, looked in the neck, and saw that something had come out, and I knew I was on to something. I cleaned it out and the hiss was gone. Good luck.
 

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Discussion Starter · #25 ·
Agree. I doubt it did it when it was new. Since that was 80 years ago, I wasn't there lol. But major surgery only as a last resort. I'm bringing the horn to a tech this morning to see if he has a quick fix or at least get another opinion on things. I guess some people just live with the hiss on the horns that do it. Some nights it bothers me more than others. I haven't owned a lot of sax's in my life but this is the first one that did this, so obviously I'm not used to it. Not sure if over time it would stop bugging me or not. Quite possibly, but I'd like to remedy it if I can.
 

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The discussion has gone way over my head with the introduction of Reynolds numbers and laminate flow. :) Nevertheless, here is my best "semi-educated" guess as to what causes the hiss and some ways to eliminate it. First go to this animation of a "standing wave". Pressure wave

Notice the "air flow" at a pressure node. There is no movement at all, but as one moves away from the location of the pressure node, the movement begins to increase.

From p. 77 of Gary Scavone's Dissertaion

"A register hole must be so located that it has a significant effect on the first resonance of an air column but little or no effect on the second resonance. Placing a register vent near a first-mode standing-wave pressure antinode and at a second-mode standing-wave pressure node will best meet these requirements. . ."

"Modern saxophones have two register holes which function for the written range D5 - G5# and A5 - F6#. . . Thus, the best tuning compromise that can be made on such instruments is to design extent. the register holes for proper operation at the notes F5 and B5, respectively. Notes on either side of these values will be sharp to a certain extent."
As you can see in the animation, at a second mode "pressure node" there is virtually no air flow for the note whose register hole is in the ideal location. But as the note moves farther and farther away from this location the air flow increases. This may be why a "hiss" is sometimes produced on a G#---3 half steps away from the ideal note, or on an A---2 half steps away from the ideal note.

A hiss is produced when air at a certain velocity passes through a restricted opening. One can make a hissing sound using the tongue to restrict the air flow when blowing a fast air stream. The hiss can be lessened or eliminated by 1) increasing the size of the opening through which the air passes OR by slowing the velocity of the air. Perhaps the mesh screen of the panty hose restricts the air flow enough to slow its escape through the octave vent. Drilling the octave vent to enlarge the hole by a few thousandths of an inch may be enough to reduce or eliminate the hiss depending upon the volume and velocity of the air flow.
 

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Distinguished Technician & SOTW Columnist. RIP, Yo
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Just another consideration...
Before messing with vent hole sizes or pantyhose, get another accomplished player to play it, and see if it hisses for them.
Reed strength, air pressure and embouchure can all have the effect of exaggerating acoustic anomalies.
If you play a clarinet with a hard enough reed, many notes will hiss.
 

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As I write this it’s 6:00 in the morning and I’m having my first cup of coffee. I’m listening to KCSM playing “Taco with a pork chop”, I’m reading SOTW and guys are talking about wrapping their octave pip in pantyhose. I can’t think of a better way to start my day.
Anyway, I had a problem with my body octave pip a while back. Some notes would speak clearly and others not. My tech cleaned the pip. Problem solved. My horn is a Martin Indiana, so similar design to most, if not all, Martin saxophones.
 

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Discussion Starter · #29 ·
Update. I went to my tech yesterday...he played it, no hiss. I had a feeling this would happen. Not saying "it's in my head" - he mentioned he may have felt a small "vibration" on D and D#, but definitely no hiss and the horn sounded sweet. I really wanted somebody else with more experience than me to play the horn. One, since no hiss, it gives me piece of mind and two, I know now mouthpiece, embouchure, reed strength etc. all factor into it. I'm convinced there is nothing "wrong" with the horn. That being said, he found a few things out of regulation (I totally expected this) and I said I'd bring it back in a month or so (after my honeymoon phase with the horn is over) to have him spruce up the keywork. So...I may ask him to gently clean out the pip while it's there, just for good measure.
 

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Usually as part of a honeymoon, clothes get taken off. Cleaning an octave pip is not a hard thing to do... yes you might have to take a couple keys off, but that's part of getting to know your horn in a more intimate, loving way!

My 1st clarinet teacher felt every musician should be able to take their instrument apart and put it back together, he even gave me a lesson on it (I was 13 at the time). He made me take some keys off in front of him to show him that I could do it. I would say most of the pros I've worked with keep a screwdriver in the case and can do small adjustments and repairs, as needed. Just sayin...
 

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If after being cleaned, the hiss remains with you, and you like your mouthpiece reed configuration, have your tech machine up a new octave pip, it’s a pretty simple job for us to do, then you can experiment with what you need.

Steve
 

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Distinguished Technician & SOTW Columnist. RIP, Yo
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...My 1st clarinet teacher felt every musician should be able to take their instrument apart and put it back together...
I find a degree of arrogance and ignorance in such statements.
Would that teacher apply the same thinking to his watch, his car engine, his printer, a sewing machine, a home appliance? A lounger? A motor mower?
I think those sorts of people might be the ones who think a half mm leak is a small leak.
But yes, I have spent my life since I was 4, taking things apart and putting them together. Not that many people do.
And only from that have I learnt my limits, and I most certainly have them.
 

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I find a degree of arrogance and ignorance in such statements.
How 'bout "naive optimism"?

I used to think that everyone should be able to sing!

And, while we're at it, shouldn't every drummer be able to keep time?
 

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Discussion Starter · #34 ·
If I had numerous saxophones, I might be inclined to "play doctor" on one of the cheaper ones in an effort to learn some basic maintenance. But I don't . I just have one tenor and one alto, so other than perhaps having one more go at gently and carefully cleaning the pip myself, I'll leave all adjustments, maintenance and key removal to someone who knows what they're doing.
 

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I find a degree of arrogance and ignorance in such statements.
Would that teacher apply the same thinking to his watch, his car engine, his printer, a sewing machine, a home appliance? A lounger? A motor mower?
I think those sorts of people might be the ones who think a half mm leak is a small leak.
But yes, I have spent my life since I was 4, taking things apart and putting them together. Not that many people do.
And only from that have I learnt my limits, and I most certainly have them.
Well, my teacher wasn't ignorant. He might have been arrogant, but for good reason, as he played very very well. You have to put this in the context of the times - this was in 1961 or so (I'm old...), and EVERYONE worked on their own car engines, sewing machines, stoves, etc. ... printers weren't a thing yet.

Having said that, I actually agree with my teacher - once a person reaches a certain age (young teens perhaps? maybe even 11 or 12?), and is playing a musical instrument, they SHOULD be able to do basic maintenance on their instruments, which means understanding, at least basically, how they work. Trumpet players should be able to take their valves out to clean and oil them, string players have to add new strings and position the bridge, woodwind players should be able to re-hook a spring, oil their instrument and maybe even put on a cork. My teacher SHOWED me how to take the clarinet apart, and what to watch out for. I'm glad he did, for though I was already mechanically inclined, there are as you well know many gotchas in the process.

I think that self-sufficiency is a great thing, and I kinda think that saying ALL repairs should be left to the great wizard-tech is also kind of arrogant. Having said that, it's important to know one's own limits, and know when "I can do this" becomes "I can't do this, gotta go see Gordon"... or whoever. I agree those limits will be different for different people.
 

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A lot depends on your perspective and experience.

I bet Gordon has had to fix a lot of horrible messes caused by hamfisted klutzes who thought they knew all about it.

I know I have led a number of people through incredibly simple mechanical repairs that they thought they had to have a professional for.

Two different sets of experience, two different conclusions about "what people should be able to do".
 

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... My 1st clarinet teacher felt every musician should be able to take their instrument apart and put it back together,
I suppose my issue is with the word "every". It assumes that every person is like oneself. They quite simply aren't.
"Every person should be able to see red and green"?
"Every person should be able to jump off a low roof"?
"Every person should be able to re-upholster a chair? Or replace a zip? Or turn a collar"?
Just because I can is never a reason that every body should be able to. We are so, so, so different. To not appreciate that is ignorance.
 
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