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Discussion Starter #1
I just put this pad sealing comparison video together last night. Various leather pads compared to Gold pads. Enjoy.

 

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Nice, I enjoyed that. Satisfying to watch. So I have one tonehole that is a little wonky on my Reference 36. It was bent, has been repaired by tenormaddness sax shop, but is maybe not perfect. Leather is nice and forgiving so it seals up. Would you do the whole horn in the gold pads, and just use a leather pad on the wonky tonehole?
 

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Discussion Starter #3
Nice, I enjoyed that. Satisfying to watch. So I have one tonehole that is a little wonky on my Reference 36. It was bent, has been repaired by tenormaddness sax shop, but is maybe not perfect. Leather is nice and forgiving so it seals up. Would you do the whole horn in the gold pads, and just use a leather pad on the wonky tonehole?
My business has me too buried in work to take on more labor. But your idea should work fine and there are several techs listed at me website that would be happy to do it. If the surface is flat - it doesn't matter if the tonehole is out of round (up to a point).

Jim
 

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Thanks for that video demonstration. I have long been a fan of your tools and products for saxophone repair. Since this topic has be an interest of mine for years, I conducted a similar test a few years ago. This is the link to that thread. Pad Porosity Study.

There were a few differences in that I tested the pads at 2"H2O and 4"H2O instead of 8 and that I used 206 grams of weight on the key cup. Even then the results were quite similar with the gold pads showing the most airtight fit. I have copied the chart below.

In my mind there are still some open questions that remain.

- How important is the "porosity" as a factor in the "acoustic efficiency" of a tonehole covering?
- Is a loss of air pressure through a porous surface the same as an opening at the edge of a pad that we refer to as a leak in saxophone repair?
- Is perfectly air tight saxophone either required or even desirable?

The highest "sound energy" I was able to measure inside a saxophone being played at its loudest level was 130 db up near the neck. That translates the .25" H2O. With that in mind, how realistic is it to test woodwind instruments for leaks using a magnehelic set at a pressure of 8"H2O

 

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Thanks for that video demonstration. I have long been a fan of your tools and products for saxophone repair. Since this topic has be an interest of mine for years, I conducted a similar test a few years ago. This is the link to that thread. Pad Porosity Study.

There were a few differences in that I tested the pads at 2"H2O and 4"H2O instead of 8 and that I used 206 grams of weight on the key cup. Even then the results were quite similar with the gold pads showing the most airtight fit. I have copied the chart below.

In my mind there are still some open questions that remain.

- How important is the "porosity" as a factor in the "acoustic efficiency" of a tonehole covering?
- Is a loss of air pressure through a porous surface the same as an opening at the edge of a pad that we refer to as a leak in saxophone repair?
- Is perfectly air tight saxophone either required or even desirable?

The highest "sound energy" I was able to measure inside a saxophone being played at its loudest level was 130 db up near the neck. That translates the .25" H2O. With that in mind, how realistic is it to test woodwind instruments for leaks using a magnehelic set at a pressure of 8"H2O
Nicely done! And some interesting questions/considerations!
 

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Discussion Starter #6
Thanks for that video demonstration. I have long been a fan of your tools and products for saxophone repair. Since this topic has be an interest of mine for years, I conducted a similar test a few years ago. This is the link to that thread. Pad Porosity Study.

There were a few differences in that I tested the pads at 2"H2O and 4"H2O instead of 8 and that I used 206 grams of weight on the key cup. Even then the results were quite similar with the gold pads showing the most airtight fit. I have copied the chart below.

In my mind there are still some open questions that remain.

- How important is the "porosity" as a factor in the "acoustic efficiency" of a tonehole covering?
- Is a loss of air pressure through a porous surface the same as an opening at the edge of a pad that we refer to as a leak in saxophone repair?
- Is perfectly air tight saxophone either required or even desirable?

The highest "sound energy" I was able to measure inside a saxophone being played at its loudest level was 130 db up near the neck. That translates the .25" H2O. With that in mind, how realistic is it to test woodwind instruments for leaks using a magnehelic set at a pressure of 8"H2O

Yes I think that porosity is the same as a leak at the tonehole. Not only that, but a soft pad that flexes or allows the cup to move up and down with the frequency of the note being played - changes the volume of the air column and also acts like a leak past the tonehole.
See this link of a test of an airtight tonehole with a very flexible "pad" that sounds terrible.

https://www.jsengineering.net/tone-vs-leakage/


Unfortunately I don't think we well get to a perfectly airtight sax - we just want to get reasonably close as practically possible. Th ideal is no toneholes at all and if you've played a horn body without toneholes then you know just how good it can sound (harmonics and fundamental only).
 

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Here is my question:

Gold pads, as I understand it, do not require a 'seat'. Leather pads, on the other hand, are typically seated when installed. The degree/depth of seating is a topic of debate among techs, but it's fair to say that leather pads when conventionally installed are seated.

So, I would be interested in seeing a demo with the leather pads seated onto your demo tonehole. I think that would be a fairer comparison.

BTW, I too applaud you for your work and products. Some fascinating stuff.
 

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Discussion Starter #8
My settings of between 2 and 4 on the vertical column and 8 on the needle with the magnehelic is what I usually use to test an entire flute - I just left it that way when testing a sax pad and it works for comparisons.
 

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Discussion Starter #9
Here is my question:

Gold pads, as I understand it, do not require a 'seat'. Leather pads, on the other hand, are typically seated when installed. The degree/depth of seating is a topic of debate among techs, but it's fair to say that leather pads when conventionally installed are seated.

So, I would be interested in seeing a demo with the leather pads seated onto your demo tonehole. I think that would be a fairer comparison.

BTW, I too applaud you for your work and products. Some fascinating stuff.
Yes that's the natural inclination but if you place a LOT OF PRESSURE on a porous leather sax pad such as the ones I've tested - they just don't seal any better. At some point the problem is not sealing at the tonehole rim - its all the air leaking through the porous area on both sides of the tonehole rim.
 

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Yes that's the natural inclination but if you place a LOT OF PRESSURE on a porous leather sax pad such as the ones I've tested - they just don't seal any better. At some point the problem is not sealing at the tonehole rim - its all the air leaking through the porous area on both sides of the tonehole rim.
Interesting point, but if I were to play devil's advocate I would say: it isn't simply a matter of pressure on the material assembly, but also the geometry of the material assembly. That is why I asked my initial question.

A cross-section of a JS pad installed properly in a key cup, resting in a closed position on the tonehole rim...is not the same as a cross section of a conventional leather pad installed properly in a keycup resting on a tonehole rim. Because a properly installed leather pad has a seat in it, thus the surface of the pad actually drops below the surface of the hole rim; sorta 'embracing' the tonehole rim ....as opposed to sitting on top of it like your pads.

So "placing a lot of pressure' on an unseated pad in order to demonstrate something... does not really mimic the reality/performance of a seated leather pad, was my point.

While I understand your focus on porosity of the pad assembly, it'd still be interesting (and a better comparison) to see the latter (leather pads seated properly on your tonehole), because that is really a more accurate example of a commonly installed leather pad.
 

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Discussion Starter #11
Interesting point, but if I were to play devil's advocate I would say: it isn't simply a matter of pressure on the material assembly, but also the geometry of the material assembly. That is why I asked my initial question.

A cross-section of a JS pad installed properly in a key cup, resting in a closed position on the tonehole rim...is not the same as a cross section of a conventional leather pad installed properly in a keycup resting on a tonehole rim. Because a properly installed leather pad has a seat in it, thus the surface of the pad actually drops below the surface of the hole rim; sorta 'embracing' the tonehole rim ....as opposed to sitting on top of it like your pads.

So "placing a lot of pressure' on an unseated pad in order to demonstrate something... does not really mimic the reality/performance of a seated leather pad, was my point.

While I understand your focus on porosity of the pad assembly, it'd still be interesting (and a better comparison) to see the latter (leather pads seated properly on your tonehole), because that is really a more accurate example of a commonly installed leather pad.
placing A LOT OF PRESSURE on the center of a pad (without putting it in a key) will give you an instant (if temporary seat). But I encourage you to do your own testing and see what you get. You may find something new.
 

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... can I ask a dumb question?

I always hear that the there is little air (flowing/velocity) actually going thru the horn but it is more of a sound wave created as a result of the reed, as regulated by tonehole closing/opening.

With the magnehelic, it is very much a function of air flow (differential?) I wonder how porosity is such a factor when the amount of air and speed/force is reportedly very low?
 

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I would disagree that it is the so called "seat" or indentation in the surface of a pad that creates the seal. Ideally it is the matching of a flat pad to a perfectly flat tonehole surface that blocks both light and air from passing through. The usual terminology "seating a pad" does lead to the "impression" (pun indented) that it is the "groove" made into the pad's surface that creates the seal. I would have to agree that may be true when using softer pads over toneholes that are not flat. That pad has to allow air to pass through the "valleys" in the tonehole surface until the tonehole edge is pressed into the pad surface to the point that a deep enough impression is created to form a "wraparound" seal.

In high end saxophone work in my experience it is more common to use firm, flat pads such as Music Medic Tan or Roo pads, or Pisoni Pros and do meticulous key fitting and alignment along with making toneholes perfectly flat to achieve leak free pads that have just a very slight impression of the tonehole when finished. In my testing using just 206 grams of pressure, there was no deep seat formed in the surface of the pad, and as can be seen from the results there were several pads that performed quite well without the deeper impression.
 

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I would disagree that it is the so called "seat" or indentation in the surface of a pad that creates the seal. Ideally it is the matching of a flat pad to a perfectly flat tonehole surface that blocks both light and air from passing through. The usual terminology "seating a pad" does lead to the "impression" (pun indented) that it is the "groove" made into the pad's surface that creates the seal. I would have to agree that may be true when using softer pads over toneholes that are not flat. That pad has to allow air to pass through the "valleys" in the tonehole surface until the tonehole edge is pressed into the pad surface to the point that a deep enough impression is created to form a "wraparound" seal.

In high end saxophone work in my experience it is more common to use firm, flat pads such as Music Medic Tan or Roo pads, or Pisoni Pros and do meticulous key fitting and alignment along with making toneholes perfectly flat to achieve leak free pads that have just a very slight impression of the tonehole when finished. In my testing using just 206 grams of pressure, there was no deep seat formed in the surface of the pad, and as can be seen from the results there were several pads that performed quite well without the deeper impression.
Good question. The magnehelic measures the differential in air "pressure" not air "flow". In a soundwave air is compressed and then expanded. During the expansion, the air molecules move the most but it is not the same as air flow because they run into air molecules going the different direction which forms a "compression" where the pressure is the greatest and the movement is the least. This location is called a "pressure anti-node". The location at which the molecules are moving the most is called a "velocity or displacement anti-node".
 

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Discussion Starter #16
I would disagree that it is the so called "seat" or indentation in the surface of a pad that creates the seal. Ideally it is the matching of a flat pad to a perfectly flat tonehole surface that blocks both light and air from passing through. The usual terminology "seating a pad" does lead to the "impression" (pun indented) that it is the "groove" made into the pad's surface that creates the seal. I would have to agree that may be true when using softer pads over toneholes that are not flat. That pad has to allow air to pass through the "valleys" in the tonehole surface until the tonehole edge is pressed into the pad surface to the point that a deep enough impression is created to form a "wraparound" seal.

In high end saxophone work in my experience it is more common to use firm, flat pads such as Music Medic Tan or Roo pads, or Pisoni Pros and do meticulous key fitting and alignment along with making toneholes perfectly flat to achieve leak free pads that have just a very slight impression of the tonehole when finished. In my testing using just 206 grams of pressure, there was no deep seat formed in the surface of the pad, and as can be seen from the results there were several pads that performed quite well without the deeper impression.
Even if you have a perfect match between the tonehole rim and a leather pad and no light is showing. The air will still pass through the porous leather that is exposed to the air column and into the felt - then sideways through the felt to the other side of the tonehole and back out through the porous leather. In other words - the air is leaking through the cushion and through the leather (not at the tonehole rim or impression).
 

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Discussion Starter #17
a bit off topic, but if a pad has a metal surface, won't there eventually be a loss of brass from the tonehole?
The pure gold layer is so thin (a few molecules thick) that you can hold it up to a light and see through it. It doesn't wear on the tonehole rim.
 

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Discussion Starter #18
... can I ask a dumb question?

I always hear that the there is little air (flowing/velocity) actually going thru the horn but it is more of a sound wave created as a result of the reed, as regulated by tonehole closing/opening.

With the magnehelic, it is very much a function of air flow (differential?) I wonder how porosity is such a factor when the amount of air and speed/force is reportedly very low?
I don't think it matters if the air is moving back and forth or in one direction. A leak is a change of air volume and if the air changes volume even for a split second - it dampens out the soundwave. For instance - even if your horn had no toneholes and no leaks. If the wall thickness was so thin (or made of flexible rubber) so that the body expanded and contacted (changed volume) it would sound weak and thin.
 

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Even if you have a perfect match between the tonehole rim and a leather pad and no light is showing. The air will still pass through the porous leather that is exposed to the air column and into the felt - then sideways through the felt to the other side of the tonehole and back out through the porous leather. In other words - the air is leaking through the cushion and through the leather (not at the tonehole rim or impression).
The reason I believe there is a difference between a pad with a typical leak and a pad that is "sealing" well and exhibits a bit of porosity through the pad surface is that I have repaired saxophones professionally for nearly 20 years. When leaks are corrected in a saxophone with traditional leather pads the saxophone plays responsively down to low Bb with a full clear tone. The finest players, both classical and jazz have sounded great for nearly 100 years playing on instruments that are in good repair and adjustment with leather covered pads that are not perfectly airtight when tested with a magnehelic.

It is a given that air under pressure can pass through the porous surface of a traditional leather pad, go sideways and out the portion of the pad outside the circumference of the tonehole. However that air meets resistance that is proportional to the thickness and density of the material(s) that it passes through. My analogy would be using a paper filter inside a funnel. The liquid does pass through eventually, but at a much slower rate than if the paper filter were removed and the liquid poured into the open funnel.

The pads that have gotten the "worst rep" for being porous since they were introduced have been the "Roo" pads from Music Medic. Part of the reason is the cellular structure of the leather itself and part is due to the fact that they have no waterproofing treatment (which is why they don't stick). Some techs will refuse to install them in customer's saxophones because they say they "leak". My personal experience playing a Selmer SBA alto for over 20 years with white roo pads in both classical and jazz settings is that they don't play as if the saxophone has a leak at every closed tonehole. There are lots of players on this forum who have written that they are happy with the roo pads installed in their saxes. Granted, my opinion may be different if I played a style of music that required the maximum edge and volume possible like the "oversize reso's" crowd. At the end of the day it may be a matter of personal taste.
 

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Discussion Starter #20
The reason I believe there is a difference between a pad with a typical leak and a pad that is "sealing" well and exhibits a bit of porosity through the pad surface is that I have repaired saxophones professionally for nearly 20 years. When leaks are corrected in a saxophone with traditional leather pads the saxophone plays responsively down to low Bb with a full clear tone. The finest players, both classical and jazz have sounded great for nearly 100 years playing on instruments that are in good repair and adjustment with leather covered pads that are not perfectly airtight when tested with a magnehelic.

It is a given that air under pressure can pass through the porous surface of a traditional leather pad, go sideways and out the portion of the pad outside the circumference of the tonehole. However that air meets resistance that is proportional to the thickness and density of the material(s) that it passes through. My analogy would be using a paper filter inside a funnel. The liquid does pass through eventually, but at a much slower rate than if the paper filter were removed and the liquid poured into the open funnel.

The pads that have gotten the "worst rep" for being porous since they were introduced have been the "Roo" pads from Music Medic. Part of the reason is the cellular structure of the leather itself and part is due to the fact that they have no waterproofing treatment (which is why they don't stick). Some techs will refuse to install them in customer's saxophones because they say they "leak". My personal experience playing a Selmer SBA alto for over 20 years with white roo pads in both classical and jazz settings is that they don't play as if the saxophone has a leak at every closed tonehole. There are lots of players on this forum who have written that they are happy with the roo pads installed in their saxes. Granted, my opinion may be different if I played a style of music that required the maximum edge and volume possible like the "oversize reso's" crowd. At the end of the day it may be a matter of personal taste.
Fortunately for sax players - the sax is not nearly as sensitive to leaks as say a flute. And its true that a sax can still play well with the porous pads. But there is a difference when you compare them to Gold pads. Have you ever installed the Gold pads and play tested them or compared them to a similar or identical horn with porous leather pads? With both horns being equally padded with careful installation and adjustment? There are different players with different preferences. A thick soft mushy leather pad with no resos will mute the tone and quiet down the horn. Some players would call it a dark tone. Others would call it a dull tone. The opposite extreme is a horn body with no pads or toneholes at all. The subtones are much easier on the horn without any pads or toneholes and the tone is fantastic. You would have the same effect if you took a horn and soldered air tight brass discs over all the toneholes and got rid of the pads. That's the effect that I'm shooting for.
 
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