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In a thread in another part of the forum, Matt Stohrer wrote an interesting post on this topic. I have taken the liberty of quoting that post as a springboard for further in depth discussion here in the acoustics section.

abadcliche said:
I keep meaning to write an article about this. I gave a long-winded answer at MusicMedic's "saxophone smackdown" last year and ever since then have been meaning to commit it to paper/web with diagrams.

Basically, in the fundamental (no octave key) you have two main acoustically sensitive spots: the area around the vibrating reed (mouth/mouthpiece chamber) and the area around the first open tonehole. More volume at the mouthpiece end lowers the overall pitch. When overblowing (octave key and altissimo) what we hear is a harmonic (a multiple of the fundamental) and so the acoustically sensitive sites are also multiplied, so the mouthpiece volume influence is diluted. Therefore, the volume of the chamber of the mouthpiece has more influence at the fundamental.

Conversely, the effective length of the sounding column is divided when overblowing, so length's role in pitch increases with the multiples (more voting power, as it were) in conjuction with a shorter sounding column (ratio).

This is why a short, large chamber piece will sharpen your palm keys and upper register and bring down your lower register. A long, small chamber piece will flatten your palm keys and upper register and sharpen your fundamental.

Of course as we are all different physiologically and we are part of the instrument while the reed is open (most of the time), your mileage may vary. But this is the acoustic framework.

Hopefully I'm making sense. I keep meaning to write an article about this. I gave a long-winded answer at MusicMedic's "saxophone smackdown" last year and ever since then have been meaning to commit it to paper/web with diagrams.

Basically, in the fundamental (no octave key) you have two main acoustically sensitive spots: the area around the vibrating reed (mouth/mouthpiece chamber) and the area around the first open tonehole. More volume at the mouthpiece end lowers the overall pitch. When overblowing (octave key and altissimo) what we hear is a harmonic (a multiple of the fundamental) and so the acoustically sensitive sites are also multiplied, so the mouthpiece volume influence is diluted. Therefore, the volume of the chamber of the mouthpiece has more influence at the fundamental.

Conversely, the effective length of the sounding column is divided when overblowing, so length's role in pitch increases with the multiples (more voting power, as it were) in conjuction with a shorter sounding column (ratio).

This is why a short, large chamber piece will sharpen your palm keys and upper register and bring down your lower register. A long, small chamber piece will flatten your palm keys and upper register and sharpen your fundamental.

Of course as we are all different physiologically and we are part of the instrument while the reed is open (most of the time), your mileage may vary. But this is the acoustic framework.

Hopefully I'm making sense.
 

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I guess what I didn't understand was the idea that a large chamber mouthpiece would have a pronounced effect on the tuning of fundamental tones (lowering them) yet less effect on their harmonics. Anyone care to offer any insight to this mathematically challenged individual?

And while I'm on the subject of the tuning of the overtone series, I seem to recall reading in the book "Voicing" (by D. Sinta) that the overtone series on a saxophone was less in tune as one goes higher on the harmonic series. And yet I hear folks say that one should try and play these in tune. Would like to hear from one of the acousticians on that. Thanks.
 

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And while I'm on the subject of the tuning of the overtone series, I seem to recall reading in the book "Voicing" (by D. Sinta) that the overtone series on a saxophone was less in tune as one goes higher on the harmonic series. And yet I hear folks say that one should try and play these in tune. Would like to hear from one of the acousticians on that. Thanks.
Might just be referring to the difference between natural tuning and the tempered scale. The higher up the harmonics go, the farther away from equal temperament the notes get. Also, perturbations in the bore (e.g., neck tenon, toneholes, etc.) at a pressure node or antinode of a note will pull the pitch up or down. So say you're playing the overtone series of low Bb. If there's a change in the bore 1/3 of the way down the horn, it will affect the 3rd (and 6th, 9th, etc) harmonic but not the others.

I guess what I didn't understand was the idea that a large chamber mouthpiece would have a pronounced effect on the tuning of fundamental tones (lowering them) yet less effect on their harmonics. Anyone care to offer any insight to this mathematically challenged individual?
Lowering the fundamental or raising the harmonics is the same depending on how you look at it. I think of it as widening the scale. A mouthpiece of a higher pitch will have a wider scale. Length affects pitch in a big way. So all other things being equal, a larger chambered piece pushed in to where it plays in tune will be shorter than a smaller chambered piece pushed it to where it plays in tune, because the pitch is higher because it is shorter.

Exactly why this happens is tough to explain in layman's terms, if you're interested read the "spread octave issue" thread (there is a good discussion there if you can ignore the personal crap), and the relevant work cited there by Benade, Nederveen, and Rocaboy.
 

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And while I'm on the subject of the tuning of the overtone series, I seem to recall reading in the book "Voicing" (by D. Sinta) that the overtone series on a saxophone was less in tune as one goes higher on the harmonic series. And yet I hear folks say that one should try and play these in tune. Would like to hear from one of the acousticians on that. Thanks.
If the harmonics are (or appear to be) out of tune, for the reasons Morgan has mentioned, then there's still no harm in attempting to play them in tune.

If they are merely appearing to be out of tune due to just intonation then it should be the players choice (as with the normal notes of the horn) to attempt to play equal temperament or not according to the context.

At other times, e.g. with false fingerings - alternate fingerings, double densities whatever you want to call them - then any difference in pitch can just add to the effectiveness of the effect.
 

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In a thread in another part of the forum, Matt Stohrer wrote an interesting post on this topic. I have taken the liberty of quoting that post as a springboard for further in depth discussion here in the acoustics section.
I may be wrong, but my understanding is that only the theoretical length of the saxophone matters. In a nutshell, what matters about the mouthpiece is the volume and the pitch. When the volume matches the missing cone the first mode (fundamentals) plays in tune (or as in tune as the horn is, rather). When the pitch matches the pitch of the missing cone the rest of the horn plays in tune. The length of the mouthpiece affects the pitch of it (and this is how it seems that mouthpiece length affects pitch), but so does chamber shape. I have done a little experimentation with this (not enough for a proper study, mind you, but enough to confirm my suspicions) and have made mouthpieces with identical volume and length but different pitch and different intonational tendencies when played.

We went into this in some detail in the "Spread octave issue" thread. I'm still currently of the opinion that MartinMods' reasoning on this is correct.
 

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I may be wrong, but my understanding is that only the theoretical length of the saxophone matters. In a nutshell, what matters about the mouthpiece is the volume and the pitch. When the volume matches the missing cone the first mode (fundamentals) plays in tune (or as in tune as the horn is, rather). When the pitch matches the pitch of the missing cone the rest of the horn plays in tune. The length of the mouthpiece affects the pitch of it (and this is how it seems that mouthpiece length affects pitch), but so does chamber shape. I have done a little experimentation with this (not enough for a proper study, mind you, but enough to confirm my suspicions) and have made mouthpieces with identical volume and length but different pitch and different intonational tendencies when played.

We went into this in some detail in the "Spread octave issue" thread. I'm still currently of the opinion that MartinMods' reasoning on this is correct.
I'll fill you in on my understanding of this, which differs significantly from Matt's:

First, any tube will have impedance peaks--frequencies where an acoustic pressure is most likely to produce and acoustic flow. These are spread out and fairly regularly spaced. The length of the tube determines the frequency of the lowest peak (more or less), and the spacing of the rest depend on the shape of the tube. With sax and clarinet, we are dealing with the case of a tube open at one end (the bell) and closed at the other (the reed end). There are only two shapes which space the impedances in such a way that they are in harmonic (integral) relationship with the fundamental--a cylinder and a straight-sided cone. The clarinet is an example of the former, and the sax of the latter. We leave the clarinet aside and concentrate on the sax.

For the impedance peaks to be really correct--exact multiples of the fundamental frequency--the cone must be complete to the tip. This is due to the physics of the wave motion. The wave in a cone is quite a bit more complex than in a cylinder, for in addition to traveling longitudinally, it expands as a spherical wavefront as it travels down the tube. The math is nasty; I guess the only one here who really understands it is Antoine, and I invite his comments and corrections.

Practically, when we cut off the end of the cone to have a place to put the mpc/reed, we throw the impedances way off. What happens is that the modes are widened. The second peak falls above the 2x multiple of the fundamental, the third peak falls even more above the 3x multiple, etc. What is happening is that overblowing the first mode to the second, then third, and on up, we are getting sharper and sharper. Basically, as the truncated part of the cone becomes a more significant fraction of the wavelength, the wave timing is thrown further and further off.

So somehow, we need to compensate for that missing part of the cone, in a way that the wave timing is preserved as it would be in a complete cone. We can do this roughly to a first approximation by making the volume inside the mpc the same as the volume of the missing part of the cone. The pressure wave travels back up the tube from the bottom, and now has to travel up through the mpc (instead of getting reflected back down at the cut off end of the tube. Even if the mpc is shorter than the cut off part of the tip, it is fatter, so the wave sort of gets slowed down in the fat part of the mpc, arriving at the reed in the same amount of time as it would take traveling faster (but further) to the tip of the cone.

For low frequencies, where the cut off part of the cone is a fairly small fraction of the total wavelength, having the mpc volume the same as the volume of the missing conic tip will sound the same frequency as a cone complete to the tip. So--to a first approximation for low frequencies--a mpc of any shape or length will sound the same fundamental frequency if its volume is the same.

But--as we start playing higher frequencies--this cozy arrangement starts to break down. The problem is that the higher impedances are still being thrown off by the shape of the mpc--it is short and squat compared to the tip of the cone: it is not a cone, and its own impedances are nothing like those of the conic tip it replaces. In the lower frequencies, this doesn't matter so much, because those higher partials are being pulled into harmonic relationship by a phenomenon called mode-locking. They are forced to behave by the strong first impedance peak. However as we go higher, the influence of the whanky impedances in the mpc become stronger and stronger.

So once we get to a certain point, the correct volume of the mpc is not enough to keep things together harmonically, because now the impedances of the mpc itself become more and more important. At this point, there is a second correction possible, which is to make sure that the first impedance peak of the mpc is the same as the first impedance peak of the missing conic tip. This is where the shape and length of the mpc become important players--not simply the length, but both shape and length, because both determine the impedances of the mpc. If the volume of the mpc is correct, and the first impedance peak (sounding resonance) of the mpc is correct, this will be enough to keep the notes in tune to the top of the horn, more or less.

What about the higher resonances of the mpc? Those will determine the higher harmonic content of the sound, while not so much affecting actual intonation. Gary Scavone did some modeling of different mpc shapes, and found that a short, fat mpc tends to play darker than a long, thin one, but that the intonational tendencies were similar.

Gary mentioned to me that Antoine had been doing some investigations on this very subject. Perhaps if he is reading this he will be kind enough to put in his own expert input.

Toby
 

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Well said Toby. There is one part of your statement that I would like expand upon with my own understanding at this point. You wrote:

kymarto said:
So once we get to a certain point, the correct volume of the mpc is not enough to keep things together harmonically, because now the impedances of the mpc itself become more and more important. At this point, there is a second correction possible, which is to make sure that the first impedance peak of the mpc is the same as the first impedance peak of the missing conic tip. This is where the shape and length of the mpc become important players--not simply the length, but both shape and length, because both determine the impedances of the mpc. If the volume of the mpc is correct, and the first impedance peak (sounding resonance) of the mpc is correct, this will be enough to keep the notes in tune to the top of the horn, more or less.
Based upon my reading of Benade, the higher frequency requirement of the missing cone substitution is that the natural frequency (Frs) of the mouthpiece + neck should match the natural frequency of the missing cone segment, which in this case is represented by the mouthpiece + neck.

This Frs as Benade calls it is determined not only by the geometry of the mouthpiece, but also is largely controlled by the player's embouchure and oral cavity as well. If I am not mistaken, determining the first impedance peak or sounding resonance of the mouthpiece must also take into account the added effects upstream in the players oral cavity and windway.

I am not yet convinced that the shape of a mouthpiece determines more than the timbre of the sound, nor that the length of the mouthpiece has any influence so long as the volume remains the same. My understanding of this is based upon:

1. The Rocaboy study found that the back and forth travel of the sound wave inside the mouthpiece during the reed closed cycle took the "time" a sound wave would take to travel to the apex of the missing cone and back. This was not based upon the physical distance from the neck opening to the tip of the mouthpiece, but rather upon the "volume" inside the mouthpiece.

2. This Mouthpiece Insert Study that I conducted a while back that suggests that it is the volume inside the mouthpiece that determines the pitch and not the length the mouthpiece extends past the neck opening.
 

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I am not yet convinced that the shape of a mouthpiece determines more than the timbre of the sound, nor that the length of the mouthpiece has any influence so long as the volume remains the same.
It is obviously possible to have two mouthpieces with identical internal volumes and different pitch tendencies. If it's not due to the shape or length, what do you think it is?
 

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Well said Toby. There is one part of your statement that I would like expand upon with my own understanding at this point. You wrote:



Based upon my reading of Benade, the higher frequency requirement of the missing cone substitution is that the natural frequency (Frs) of the mouthpiece + neck should match the natural frequency of the missing cone segment, which in this case is represented by the mouthpiece + neck.

This Frs as Benade calls it is determined not only by the geometry of the mouthpiece, but also is largely controlled by the player's embouchure and oral cavity as well. If I am not mistaken, determining the first impedance peak or sounding resonance of the mouthpiece must also take into account the added effects upstream in the players oral cavity and windway.

I am not yet convinced that the shape of a mouthpiece determines more than the timbre of the sound, nor that the length of the mouthpiece has any influence so long as the volume remains the same. My understanding of this is based upon:

1. The Rocaboy study found that the back and forth travel of the sound wave inside the mouthpiece during the reed closed cycle took the "time" a sound wave would take to travel to the apex of the missing cone and back. This was not based upon the physical distance from the neck opening to the tip of the mouthpiece, but rather upon the "volume" inside the mouthpiece.

2. This Mouthpiece Insert Study that I conducted a while back that suggests that it is the volume inside the mouthpiece that determines the pitch and not the length the mouthpiece extends past the neck opening.
John--

Yes, the embouchure has an effect on the mpc volume and the resonance frequency by changing the volume under the reed. There may also be other reed effects I am not taking into account. However Benade is giving us a down and dirty practical way of determining the resonance by including a convenient part of the instrument. Ideally, we would want only the mpc to the neck insertion plus the neck diameter, but this is practically impossible, so the Benade method of using the sax on the neck or the reed on the staple (for oboe) gets us in the ballpark. If Joe Wolfe is to be believed, there are no significant upstream effects to take into account if one is playing normally.

I agree with your second statement: Scavone found no significant intonational differences based on length (nor did Wyman), although both report significant timbral differences based on varying mpc shapes (which includes length). Hopefully Antoine can add something, as I believe that he was studying this.
 

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It is obviously possible to have two mouthpieces with identical internal volumes and different pitch tendencies. If it's not due to the shape or length, what do you think it is?
I am not disagreeing with this claim, however I have not seen any studies or data that would prove or disprove this statement. I do believe that tip opening and reed strength have a degree of influence over the way the player plays the mouthpiece which in turn has an effect upon the mouthpiece effective or equivalent volume which affects the pitch. In this Mouthpiece Equivalent Volume study I did which replicated the method used by Benade and Gebler FMA p.466, I could have skewed the results by playing with a much higher or lower mouthpiece pitch than I normally use on the tested mouthpiece.

I believe it is important to remember that it is this "equivalent" volume that the truncated tube sees as its "missing cone", and not the measured geometric volume of the interior of the mouthpiece past the neck opening.

I guess the point I am trying to get across is that it is difficult to generalize that mouthpiece A does X to the pitch of the palm key notes, while mouthpiece B does Y to those same notes without taking into account the variable that the player contributes to the mix.
 

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EE: Imagine a table with 3 legs. Then add a 4th, and 5th, and so on. The more legs the table has, the less weight the legs each carry. This is representative of the divided effect on acoustically sensitive spots as the number of harmonics increase (first by adding the octave key, then by playing altissimo) and multiply the number of acoustically sensitive spots. There are more spots, but each one now carries less weight individually. So therefore the more legs you have the less a change on one affects the rest.

Now imagine 10 foot long rope. You fold it in half, you have a double strand of rope 5 feet long. Fold it in half again, you have a quadruple strand of rope 2.5 feet long. Now unfold it, cut off a foot. Your rope is now 90% of the length it was before. Fold it in half, you have a double strand of rope 4.5 feet long, 90% of the original length. Fold it in half again, you have a quadruple strand of rope 2.25 feet long, 90% of the original length. So no matter how many times you fold it, the effect of a change in length remains the same.


So while a volume change at one point in the bore (like the mouthpiece) becomes less effective as harmonics are multiplied, a change in length has a constant effect. Now combine this with the fact that in (for example) the palm keys, the first open tonehole is closer to the mouthpiece vs. low Bb (overall sounding column length). Therefore a given amount of length lost through pushing in or a shorter mouthpiece will be MORE by ratio than for a open tonehole further down the bore. (1/4 inch of 12 inches has twice the effect of 1/4 inch of 24 inches)

Add these two factors together and you've got the real world effect: volume has more to do with the fundamental, and the higher up you go the more the length has an effect.

I think in my first post I worded this terribly. Hopefully this is clearer.


Volume most definitely has an effect on tuning- the internal volume of the saxophone matters, right? The internal volume of the neck matters for 2nd octave (and above) tuning, right? Well while inside the saxophone body the acoustically important spots move around depending on the note being played, the mouthpiece is ALWAYS an acoustically important spot, same as the first open tonehole. This is why opening your throat and making your oral cavity bigger will drop the pitch of any note.


The effect of volume and length on tuning is easy to test empirically, I suggest giving it a go. Measure the distance from the back of the neck cork to the tip of the mouthpiece, and play a low Bb (or any low note, where the effect will be maximized) with a small chamber piece and a large chamber piece with the tip of the reed in the same spot. thus ensuring identical overall length from the tip of the reed to the open bell. The low Bb will go down for the large chamber piece.

Now take a large chamber stubby piece and a small chamber long piece and tune them to Bb or A concert. You will notice that the distance from the back of the neck cork to the tip of the reed is different- you'll be farther in for the large chamber piece (although it may look like you are farther off the cork because the piece itself is shorter). Now play up in the palm keys. The stubbier piece will sharpen your palm keys relative to the rest of the horn because the added volume brought the pitch down in the fundamental, necessitating pushing farther in to get it in tune- and now that you are playing harmonics, the effect of the volume of the mouthpiece is divided between more acoustically sensitive spots (like in the neck) and the effect is lessened, so you start to go sharper.


This volume/length relationship is one way to control octave spread or squeeze. The mouthpiece is one part of a complicated and interconnected system so understanding this is not an intonational panacea, but it definitely helps.


Now if you'll excuse me, my brain hurts and I am going to go polish a saxophone. :bluewink:
 

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EE- regarding the overtone series being difficult to play in tune: as you go higher and higher in the series, smaller differences in the bore in more places (mouthpiece, horn, mouth) add up, making it more likely that the intonation will be off (kind of like how the lower you go, the more pads you have down so the more likely it is a leak exists so you usually feel leaks more on low Bb than you do on open C#).

Also, as any piccolo or sopranino player will tell you, the intonation of higher tones is harder to control as smaller changes in your embouchure/throat will affect bigger changes in the intonation (and also the notes are farther apart hertz-wise, which makes smaller changes SOUND more out-of-tune).

So for these reasons it is both difficult AND possible- you have a handicap, but with a good ear and good voicing in the throat you can usually do it. It might not be practical, but it is good practice.
 

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This is why opening your throat and making your oral cavity bigger will drop the pitch of any note.
Actually, changing pitch with the oral cavity alone (without pressure change at the reed) is something I've never been able to do, but that's another conversation.

The stubbier piece will sharpen your palm keys relative to the rest of the horn because the added volume brought the pitch down in the fundamental, necessitating pushing farther in to get it in tune- and now that you are playing harmonics, the effect of the volume of the mouthpiece is divided between more acoustically sensitive spots (like in the neck) and the effect is lessened, so you start to go sharper.
My mouthpiece is a Lebayle LR II (large chamber) but I don't have a small chamber piece for comparison. Best I could come up with was an old Berg Larson 100/2 M and a '70s Dukoff 10. They are both substantially longer. Tried the examples as you laid them out and can't say I was able to reproduce those results. Yes, the shorter mouthpiece wants to be further on the neck to tune properly. But the palm keys are not noticeably sharper than when playing the longer mouthpieces. But then my horn (1927 Conn tenor) is like a violin with respect to pitch on any given note and may be obscuring the role of the mouthpieces somewhat.

Now if you'll excuse me, my brain hurts and I am going to go polish a saxophone. :bluewink:
Thanks for your explanations though, I get the logic of what you're saying. And I do appreciate the time, effort and brain-ache!

At the risk of bringing on a migraine, here's another question. What acoustic properties would make a horn more or less flexible with respect to pitch? My Selmers are quite locked in by comparison to the Conn.

EE- regarding the overtone series being difficult to play in tune: as you go higher and higher in the series, smaller differences in the bore in more places (mouthpiece, horn, mouth) add up, making it more likely that the intonation will be off
Yes, true. I should have perhaps specified that I find a big difference in the way the overtones tune when playing the series off the low Bb as compared to the series off a low Db for example. The series on the low Db seems to go out of whack sooner and more dramatically.
 

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"What acoustic properties would make a horn more or less flexible with respect to pitch? My Selmers are quite locked in by comparison to the Conn."

I wish I knew! Same goes for "mouthpiece-friendly". Anybody know?


To illustrate the examples I spoke about, I would use a short/stubby large chamber mouthpiece with scooped sidewalls like an old Conn Eagle or a Buescher HR and a more modern piece like a Selmer C*. I don't know if a Lebayle vs. a Berg is really going to do much.
 

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I just borrowed one of those old Conn mouthpieces from a student recently and I can say that the chamber of the Lebayle LR II is comparably large (pretty huge actually, which is why your original comment caught my eye). As for the the Berg and the Dukoff, they are each the better part of a centimeter longer than the Lebayle. I also regularly play a Francois Louis which is the longest of the bunch. Haven't noticed any real difference in pitch tendencies between the Louis and the Lebayle. But again, my horn may be overriding these tendencies. Plus the tip openings are large-ish (#8).
 

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I would suggest retrying it with a piece with scooped sidewalls like the Conn. Your Lebayle does have a large chamber, but it has a rollover baffle and mostly straight sidewalls. Not to belabor the point, but its kind of an important one- for the purposes of this experiment, you really need to use pieces at the extreme ends of the spectrum to make it easily noticeable.


The acoustics behind my statements are actually just very basic fundamentals- the rules of nodes and antinodes of standing waves. The open end (tonehole or bell) is always a displacement antinode (pressure = minimal). The mouthpiece/reed is always a displacement node (pressure = maximal). Increasing internal volume at a displacement antinode raises the pitch, decreasing internal volume at a displacement antinode lowers pitch. Increasing internal volume at a displacement node lowers pitch, decreasing volume at a displacement node raises pitch. For a pretty accessible rundown, I suggest "The Saxophone Is My Voice" by Ernest Ferron. The only problem I have with this stuff is that I am constantly getting my negatives mixed up, and the terminology seems overfull of double negatives if you ask me!

These are concepts that are already readily accepted- such as dents on a neck, or liners in a neck, dents across from a tonehole, dents in the bow... when people say that a dent in your neck is going to affect intonation of a note or notes in your upper octave, it is because you are reducing the volume of the bore at that a nodal point.

Unless I've completely misunderstood it, that is. However, I've read an awful lot, spoken about this with many repairmen and instrument makers and done lots of experimenting before saying this sort of stuff out loud. Kymarto might even remember me asking him about this about 4 years ago! He disagreed with me then, and it caused me to keep researching and experimenting for quite a while longer. So I guess I've been working on this and thinking about it for about 5 years now. If the majority of folks disagree, well then I'll have to go back and figure out why I am seeing what I see, and why I can predict the results of changing the volume and length like I mention.

Saxophone acoustics is a very, very complicated and intricate web of interacting variables. The mouthpiece volume/length stuff is just part of it, but an important one, especially if you are playing a modern high baffle straight sidewalls small chamber piece on an old horn and find your palm keys flat and you bell keys sharp- try a shorter mouthpiece with more internal volume (low baffle, scooped sidewalls, large chamber)! It might just get you back in tune.

Found a fairly accessible introduction to saxophone acoustics here: http://www.phys.unsw.edu.au/jw/saxacoustics.html
 

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I would suggest retrying it with a piece with scooped sidewalls like the Conn. Your Lebayle does have a large chamber, but it has a rollover baffle and mostly straight sidewalls. Not to belabor the point, but its kind of an important one- for the purposes of this experiment, you really need to use pieces at the extreme ends of the spectrum to make it easily noticeable...Saxophone acoustics is a very, very complicated and intricate web of interacting variables. The mouthpiece volume/length stuff is just part of it, but an important one, especially if you are playing a modern high baffle straight sidewalls small chamber piece on an old horn and find your palm keys flat and you bell keys sharp- try a shorter mouthpiece with more internal volume (low baffle, scooped sidewalls, large chamber)! It might just get you back in tune.
Matt,
Have you seen the Lebayle hard rubber LR II? The sidewalls are not straight at all, they are very much scooped out. And I had Fred Lebayle remove the rollover completely. In comparing it to the vintage Conn mouthpiece it's at least as "extreme" in these regards. Just so you know…

Also, those other mouthpieces I mentioned are old ones that I pulled out for the experiment. Haven't otherwise played them in years. And my comments about the Conn tenor being like a violin is the reason I dig it so much. I wasn't asking about your comment because of difficulty with intonation. I am simply curious to learn how the horn works and your comment struck me as curious. I'm not disagreeing with the premise (although it seems at least one of the above posters may be). Just trying to understand and experience it.

Thanks again for taking the time...EE
 

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Ah, no I had not seen the HR version, only the metal.

I completely agree with you about the flexibility of Conn NWII ("Chu") horns. They take skill to control but are soooo rewarding with that TONE they get! I have no idea why it would be, but in my experience it seems like the more locked-in a horn is, the less interesting the tone. Doesn't mean it has a BAD tone, just like its more pure. Yamahas. for instance. Great intonation that requires little work on the part of the player, but to my ears a relatively simple tonality. Then take a "Chu"- takes some player input to convince it to play in tune, but the tone is complex and rich. Maybe in 10 years I'll have an explanation!

PS: I'd be interested to hear how your intonation changes if you put a modern C* on your horn.
 

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EE: Imagine a table with 3 legs. Then add a 4th, and 5th, and so on. The more legs the table has, the less weight the legs each carry. This is representative of the divided effect on acoustically sensitive spots as the number of harmonics increase (first by adding the octave key, then by playing altissimo) and multiply the number of acoustically sensitive spots. There are more spots, but each one now carries less weight individually. So therefore the more legs you have the less a change on one affects the rest.

Now imagine 10 foot long rope. You fold it in half, you have a double strand of rope 5 feet long. Fold it in half again, you have a quadruple strand of rope 2.5 feet long. Now unfold it, cut off a foot. Your rope is now 90% of the length it was before. Fold it in half, you have a double strand of rope 4.5 feet long, 90% of the original length. Fold it in half again, you have a quadruple strand of rope 2.25 feet long, 90% of the original length. So no matter how many times you fold it, the effect of a change in length remains the same.


So while a volume change at one point in the bore (like the mouthpiece) becomes less effective as harmonics are multiplied, a change in length has a constant effect. Now combine this with the fact that in (for example) the palm keys, the first open tonehole is closer to the mouthpiece vs. low Bb (overall sounding column length). Therefore a given amount of length lost through pushing in or a shorter mouthpiece will be MORE by ratio than for a open tonehole further down the bore. (1/4 inch of 12 inches has twice the effect of 1/4 inch of 24 inches)

Add these two factors together and you've got the real world effect: volume has more to do with the fundamental, and the higher up you go the more the length has an effect.
Matt, sorry, but this is really inaccurate. You might as well be talking about adding legs to an airplane--it is not a good analogy. Several factors have to be taken into account. First and foremost one has to start with the impedance profile. Any tube has impedance peaks at which frequencies the standing wave is most likely to form, but where it actually does form depends on a complex interaction of all the peaks, and the salient factors there are the height of the peaks, their width and their position. Those are the factors that give them their "voting power" in the caucus.

A standing wave--to exist--must have exact harmonics. If the impedance peaks are not at those exact frequency multiples, everyone has to accomodate and move around until they are. The strongest peaks move the least. Those that move pay a penalty--the farther they have to move the weaker they become in the final sound.

And it is not over there--those shifted frequencies keep trying to get back to their peaks. They can be helped to do so in several ways. First, partial content increases at higher dynamics. So as you blow harder--up to a point--the partials grow in strength as the power of their order. Simplified, that means that as you blow hard enough to make the fundamental twice as loud, the 2nd partial gets 4x as loud, the 3rd 9x as loud, etc.

So as those partials gain strength, they use their increased voting power to try to get more money for their home district. Further, if everybody is comfortable at home, they can cooperate and support each other, but if they are engaged in a big tug-of-war, it's every partial for himself.

A horn with well-aligned impedances will respond more quickly, be more pitch-stable, generally feel and act more centered and have more output for a given input. Just like facial features: everybody has two eyes, a nose and a mouth, but their shape and size and relation to each other, changed even minutely, can make some people strikingly attractive and others seem homely.

The shape of the peaks also has a role to play. A broad peak can move farther and still have energy to participate, and (I believe) is more "relaxed" about getting on peak.

Beyond that, you have the influence of the reed itself and the constantly changing effective mpc volume, making the floor of all this less than solid.

There are several reasons that higher notes get more slippery. First, frequency dependence of mpc volume changes mean that higher modes are affected increasingly as the volume changes with embouchure adjustments. Short-tube notes are also effected more than long-tube notes.

Add to that the fact that short-tube notes tend to have weaker peaks, so that reed effects are more pronounced.

So much about the character of a horn--the response, timbre and intonational stability--is determined by the impedances of the bore, and they change for every fingering.

As far as the mpc goes: it is dangerous to generalize. The intonational tendencies of the high notes are influenced by the impedance profile of the mpc. The complex shape inside a mpc means that there is no simple relationship between length and the position of the impedance peaks. In Wyman's study, some of the longest mpcs played sharpest in the palms and vice-versa. Further, the baffle shape influences reed behavior aero-acoustically, which could also be significant independent of the impedances.
 
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