Definition of a leak

[Gheorghe]

This is a very amateur question, but how perfectly do things need to seal? When I take the top joint of my taragot (without mpc), cover the 3 holes, block the bottom with my right palm, and blow into the joint with decent amount of air, some of the air escapes under some of the pads. Now I figure that with enough air pressure, eventually ANY pad would let air escape. But is there a rule of thumb for what is good enough?

For instance, my low Bb key (the one located all the way on the bell), does not seal at all, yet I can play that note when I have to. It's far from ideal though.

George

 

[LowThudd]

This is a very amateur question, but how perfectly do things need to seal? When I take the top joint of my taragot (without mpc), cover the 3 holes, block the bottom with my right palm, and blow into the joint with decent amount of air, some of the air escapes under some of the pads. Now I figure that with enough air pressure, eventually ANY pad would let air escape. But is there a rule of thumb for what is good enough?

For instance, my low Bb key (the one located all the way on the bell), does not seal at all, yet I can play that note when I have to. It's far from ideal though.

George

A leak light will tell you if your pads are seating enough. You get one for #$15 on eBay, or, somewhere on this site I believe are instructions for making your own. Basically though, you just need a light that will fit into the bore to behind the pad you are checking. This is the one I bought. Seems to work OK, and the price is right.

 

[Gheorghe]

A leak light will tell you if your pads are seating enough. You get one for #$15 on eBay, or, somewhere on this site I believe are instructions for making your own. Basically though, you just need a light that will fit into the bore to behind the pad you are checking. This is the one I bought. Seems to work OK, and the price is right.

That's it?? Well I happen to have one of those I use it inside my double bass when adjusting the sound post.

Glad I asked!

Thanks.

George

 

[Steve]

make them yourself leak lights
http://www.woodwindforum.com/forum/...e-led-leak-light-you-can-make-yourself.22959/

http://www.woodwindforum.com/forum/index.php?threads/do-it-yourself-leaklight.22888/#post-219669

at home leak test
http://www.woodwindforum.com/forum/index.php?threads/at-home-clarinet-leak-test.20682/


A leak can be compromised of a variety of things.

first and foremost the pads not covering 100% the tonehole. This is definitely a leak. The pad has to cover then entire circumference of the tonehole, uniformily to create a good air-tightness seal.

If you create a vacuum (suck) into an instrument you may get an airtight seal.

If you blow a little it may not let air out. As you increase your blowing pressure you may overcome the tension strength in a spring. On clarinets this happens often on the throat Ab and the RH pinky Eb key.

The instrument material itself may have deep crevices, etc which is in essense a leak too - it will take pressure away from playing and the tone and response may suffer. Or air penetration through a tonehole.

pads, older more fragile (or really cheap) ones may allow air penetration through their skin. This is like a leak too and the instrument may play but response and tone may not be 100%

pads vary in their air penetration. I did some tests at some time with a percentage but basically single bladder allow some air penetration, double bladder, leather, then synthetics. Synthetics normally being the most air tight and single bladder has some air penetration.

keep in mind different brand pads vary in all aspects and even the same pad brand/make may vary.

of course a cut in a pad too creates a nice leak. I had one in my Selmer alto sax (palm D) in high school for years until I found it. The tech didn't. horn played great but afterwards was even better. I had response issues on the low notes but no one could ever find a problem because it was up top!!

 

[Gheorghe]

make them yourself leak lights
http://www.woodwindforum.com/forum/...e-led-leak-light-you-can-make-yourself.22959/

http://www.woodwindforum.com/forum/index.php?threads/do-it-yourself-leaklight.22888/#post-219669

at home leak test
http://www.woodwindforum.com/forum/showthread.php?t=842


A leak can be compromised of a variety of things.

first and foremost the pads not covering 100% the tonehole. This is definitely a leak. The pad has to cover then entire circumference of the tonehole, uniformily to create a good air-tightness seal.

If you create a vacuum (suck) into an instrument you may get an airtight seal.

If you blow a little it may not let air out. As you increase your blowing pressure you may overcome the tension strength in a spring. On clarinets this happens often on the throat Ab and the RH pinky Eb key.

The instrument material itself may have deep crevices, etc which is in essense a leak too - it will take pressure away from playing and the tone and response may suffer. Or air penetration through a tonehole.

pads, older more fragile (or really cheap) ones may allow air penetration through their skin. This is like a leak too and the instrument may play but response and tone may not be 100%

pads vary in their air penetration. I did some tests at some time with a percentage but basically single bladder allow some air penetration, double bladder, leather, then synthetics. Synthetics normally being the most air tight and single bladder has some air penetration.

keep in mind different brand pads vary in all aspects and even the same pad brand/make may vary.

of course a cut in a pad too creates a nice leak. I had one in my Selmer alto sax (palm D) in high school for years until I found it. The tech didn't. horn played great but afterwards was even better. I had response issues on the low notes but no one could ever find a problem because it was up top!!

Great info, thanks Steve! I just learned something so obvious that I feel embarrassed for not thinking of it first - creating suction instead of blowing into the joint in order to check for leaks. Looks like I need to explore other areas of this forum.

 

[LowThudd]

SteveSklar, lot's of great info. Thanks.

pads vary in their air penetration. I did some tests at some time with a percentage but basically single bladder allow some air penetration, double bladder, leather, then synthetics. Synthetics normally being the most air tight and single bladder has some air penetration.

That's interesting about the synthetics, especially because they are usually less expensive. Just curious, why is leather more sought after and expensive? I had planned on using much more expensive leather pads on my next sax build. The pads I bought were cheap and from two sources, half synthetic and half were leather(though they were advertised as synthetic). Does leather just have a better feel, or does it last longer?

 

[Gheorghe]

SteveSklar, lot's of great info. Thanks.




That's interesting about the synthetics, especially because they are usually less expensive. Just curious, why is leather more sought after and expensive? I had planned on using much more expensive leather pads on my next sax build. The pads I bought were cheap and from two sources, half synthetic and half were leather(though they were advertised as synthetic). Does leather just have a better feel, or does it last longer?

I asked the tech I went to about the materials, and he told me he found leather pads for me because he saw that the original pads are leather also.

George

 

[Steve]

if you do a suction test be careful on how much vacuum you create. With bladder pads (such as on a clarinet) you can weaken the covering as the "bladder" or goldskin, is a very thin material. Once it separates it can become an active member of the harmonics of the instrument .. usually making an annoying buzz sound.

leather pads are normally thicker and more forgiving to slightly unflat toneholes.

leather comes in a variety of type of leathers, such as regular calf leather and kangaroo leather. You can also get colors (dyed) of tan, white and black.

but you can also get leather with a water seal put on it, making it more air tight until the seal wears off.

of course the stuff behind the leather or bladder is also important. normally it's felt and that could be a woven or pressed felt. I stick with the pressed felt. But it all varies with the makers .. basically you get what you pay for. On pads (such as sax) that have a resonator that resonator helps to keep the leather material tight and adds strength to the entire thing. Sax pads evolved too, originally there were just metal rivets, nowadays you can probably get custom graphic/painted images on your resonators (did I just create another industry ?)

the backing material and thickness is important too as it allows the pad to keep flat throughout the entire storage, installation, usage cycle.
ie, a basic breakdown of a pad is bladder/leather covering, felt interior, and a cardboard backing (the leather and bladder are wrapped around the felt and are glued to the backside of the cardboard).

synthetic pad materials vary greatly in construction.

cheap synthetics are cheaper than regular pads.
for instance, using Buffet goretex pads adds just material-wise another $120ish to a repad on a clarinet.

regular Valentino pads I believe are more expensive and Valentino Master Pads are more expensive then regular bladder or leather pads.

If we go back in history to the evolution of tonehole sealing materials I believe it started out with just felt as a sealing material. Kind of pourous I would think. Then they added a layer of leather to that ... it's just what was available and someone did it. So historically older instruments had leather pads.

 

[SOTSDO]

The phantom B natural problem

I had a pad on my main bass clarinet that bedeviled me for many, many years. It was on the pad through which the B natural below the staff was vented when played with the "forked" fingering. This note (and the F# above) were both badly muffled, so much so that I became quite adroit at playing almost every one with the sliver key, even in relatively fast passages.

I took it in to a number of technicians, but the problem remained until I tried a noted repair person up in Dallas when up there on a business trip. He was as puzzled as the rest after applying all of the standard tests, but he took the time to remove the key from the horn, there to find that the pad had been cut by the inside edge of the tone hole, but that the flap that resulted remained in place against the felt unless there was airflow through the tone hole, at which time it was drawn downwards by the flow and thus "veiled" the tone.

We theorized that most folks applied the standard tests, looked at the pad in place as best as they could, but never bothered to pull the key work from horn (as it involved a bit of disassembly). Once it was removed, however, the problem was immediately apparent.

So, the morale of the story is that a leak light and a feeler don't always diagnose the problem.

I still find myself avoiding the "forked" fingering for these notes. Old habits are hard to undo...

I believe that the first "clapper" style keys (used on instruments where the tone holes were too big or too far removed from the finger position, most notably on the bassoon) were faced with leather. That's what all of the histories that I have on woodwind instruments claim. The felt came later.

 

[CHasR]

under coprechiave

imho its the bagpipe (once again!) thats in the forefront of woodwind development where primitive keys are concerened. The zampogna a chiave (zampogna with key) existed in its current form sometime prior to the black death: a fresco in the church of Roccaravindola in Molise depicting the instrument has been dated to 1320's.
One can see the zampogna's coprechiave (key cover) here:
in use on many instruments in Praetorius Sitgmata, as well as in other continental pipes, and is crafted the very same way even today.
The keypad is usually just a flattened piece of metal that sits flush when closed on a flatened area around the tone hole. The simple mechanism is exposed in the picture above. I have seen goatskin, leather, rubber, vynil, and cork used to improve the metal's seal; but when expertly crafted, metal on wood will provide a lasting airtight seal (at least until the key gets bent!)
Personally, I've always preferred cork pads wherever possible, but that's just me.

incidentally, its an old-school, *very* politically incorrect way of finding leaks, but cigarette smoke blown into the suspect piece will generally always let you know where the leak is.

 

[LowThudd]

incidentally, its an old-school, *very* politically incorrect way of finding leaks, but cigarette smoke blown into the suspect piece will generally always let you know where the leak is.

Aah. That brings back memories of when I was a kid at the Renaissance Faire, I saw Scotts do that(although it was tobacco smoke from a clay pipe). Had no idea what they were up to. I wasn't sure it was "legal" smoke, lol

 

[CHasR]

Aah. That brings back memories of when I was a kid at the Renaissance Faire, I saw Scotts do that(although it was tobacco smoke from a clay pipe). Had no idea what they were up to. I wasn't sure it was "legal" smoke, lol

lol. trust me, if it was a highland piper, a generation ago, it was defnintely tobbacco. even at an SCA shindig.
although, that method was used primarily to find splits in the wood. as opposed to key leaks.

 

[jbtsax]

make them yourself leak lights
http://www.woodwindforum.com/forum/...e-led-leak-light-you-can-make-yourself.22959/

Unfortunately I no longer advise making this LED leak light using the parts given in the linked article. After a minimum of use each of the prototypes stopped working after the plastic got bent a few times It seems that the ultra cheap Chinese LED lights behaved exactly as one might expect a product in that price range to behave.

If someone wants a good LED leak light, I recommend the one from Music Medic.

 

[LowThudd]

lol. trust me, if it was a highland piper, a generation ago, it was defnintely tobbacco. even at an SCA shindig.
although, that method was used primarily to find splits in the wood. as opposed to key leaks.

Was probably better than 25 years ago, but I suspect it was tobacco. Just wasn't quite sure at the time. The memory got locked up until you mentioned the practice.

 

[clarnibass]

No matter what you do it will not be "perfect". For a start, the wood body probably doesn't seal as perfectly as something like a coke bottle. Then you have the materials of the pads and invisible chips to the tone holes (as opposed to ones that are visible with a magnifier, I mean ones that would only be possible to see with a microscope probably). Basically this means it is just not perfect. Then there is flexing of keys, which causes the mutually exclusive principles of equal closing pressure and simultanous closing. This means you need a certain amount of force to close the keys and weaker than that you'll get a significant leak. This amount of force is usually described as light finger pressure.

But all these things can be made to a degree where the instrument plays excellent. This condition is such that any further improvement might not even be noticable. It's hard to say really. I have even seen some instruments that didn't seal as "perfectly" as others (of same model) but played better.

There is another reason to get as accurate as possible. After repairs, things start to deteriorate. A pad starts a long process until it is eventually leaking. For some pads it can take longer than your life, for some it will be much faster. The more accurate you get a pad to seal (even more accurate than is possible to feel a difference i.e. to overcome basic light touch from the finger), the longer it will remain in good condition. It will still deteriorate but longer in that process it will keep a good seal with light finger pressure (I hope this explanation is clear).

As far as the pads, my tests were similar to Steve's re what pads sealed better. However there are other advantages and disadvantages to different pads and all could get an excellent seal, as long as the specific ones were good.

IME good synthetic pads cost more than bladder pads. At least I haven't seen a synthetic pad I liked that cost less than good quality bladder pads.

Re suction and blowing, I don't really like the suction test. I found that it can suck the pads "into" the tone holes and make it seem like there is no or less of a leak than there really is. This is especially true for flutes, but also other instruments. It can be a good initial test to find serious leaks i.e. if there is terrible suction or no suction, there's probably a leak. It can even help find where it is, etc. but it's not so good at finding smaller leaks.

Blowing is better and you can then press different keys stronger with your fingers to see when it improves, finding the problematic keys. But just blowing normally is not the best IMO. It is better to "squirt" air out of your mouth by forcing the air that is already there out. It a bit like blowing your cheeks and forcing the air out of your mouth, without using blowing from the lungs, except you are not blowing your cheeks. It's a bit hard to explain but very easy to do. This has a much better feel by your mouth to the leaks and the degrees of leaks. I can basically use this method intead of a magnehelic (I have one and prefer to use it for other reasons, the "mouthehelic" works just the same for this purpose).

but he took the time to remove the key from the horn

When a note is stuffy and there isn't a more obvious reason why, taking the key off to check how it plays with the key off is a very basic test. Strange that no one else tried it before him. BTW if it was an old Selmer bass clarinet, many of those have a slightly stuffy low B regardless of pad (but not so much that you can't use the fingering!).

 

[SOTSDO]

I imagine...

...that the over arching knowledge of the "stuffy" note was probably the excuse that the other technicians used to dismiss the issue in their minds.

Nonetheless, it did give me incentive to obtain greater facility with the remaining fingering...

 

[Gheorghe]

Light test showed a major leak

Thanks to yesterdays posts, I discovered the leak in my upper joint that I'm pretty sure is the major contributor to my instrument wanting to jump to the 2nd octave when playing the lowest notes. The light test showed obvious gap between the pad and the tone hole, and blowing/vacuum test proved it (vacuum cannot be created). I'm not one bit surprised at it jumping to 2nd octave, as it is comparable to half-holing the LH1 key, which has been recommended as an alternative to using the octave key for playing the 1st few notes of the 2nd octave.

On a few other keys in the middle joint, I see a bit of the light seeping through, but I think that's just the strong light going through the edges of the leather on the pads - on that joint, it is very easy to create vacuum via suction (realizing that this test might be a bit forgiving).

Thanks again for the great tips!

George

 

[LowThudd]

No matter what you do it will not be "perfect". For a start, the wood body probably doesn't seal as perfectly as something like a coke bottle. Then you have the materials of the pads and invisible chips to the tone holes (as opposed to ones that are visible with a magnifier, I mean ones that would only be possible to see with a microscope probably). Basically this means it is just not perfect. Then there is flexing of keys, which causes the mutually exclusive principles of equal closing pressure and simultanous closing. This means you need a certain amount of force to close the keys and weaker than that you'll get a significant leak. This amount of force is usually described as light finger pressure.

But all these things can be made to a degree where the instrument plays excellent. This condition is such that any further improvement might not even be noticable. It's hard to say really. I have even seen some instruments that didn't seal as "perfectly" as others (of same model) but played better.

There is another reason to get as accurate as possible. After repairs, things start to deteriorate. A pad starts a long process until it is eventually leaking. For some pads it can take longer than your life, for some it will be much faster. The more accurate you get a pad to seal (even more accurate than is possible to feel a difference i.e. to overcome basic light touch from the finger), the longer it will remain in good condition. It will still deteriorate but longer in that process it will keep a good seal with light finger pressure (I hope this explanation is clear).

As far as the pads, my tests were similar to Steve's re what pads sealed better. However there are other advantages and disadvantages to different pads and all could get an excellent seal, as long as the specific ones were good.

IME good synthetic pads cost more than bladder pads. At least I haven't seen a synthetic pad I liked that cost less than good quality bladder pads.

Re suction and blowing, I don't really like the suction test. I found that it can suck the pads "into" the tone holes and make it seem like there is no or less of a leak than there really is. This is especially true for flutes, but also other instruments. It can be a good initial test to find serious leaks i.e. if there is terrible suction or no suction, there's probably a leak. It can even help find where it is, etc. but it's not so good at finding smaller leaks.

Blowing is better and you can then press different keys stronger with your fingers to see when it improves, finding the problematic keys. But just blowing normally is not the best IMO. It is better to "squirt" air out of your mouth by forcing the air that is already there out. It a bit like blowing your cheeks and forcing the air out of your mouth, without using blowing from the lungs, except you are not blowing your cheeks. It's a bit hard to explain but very easy to do. This has a much better feel by your mouth to the leaks and the degrees of leaks. I can basically use this method intead of a magnehelic (I have one and prefer to use it for other reasons, the "mouthehelic" works just the same for this purpose).


When a note is stuffy and there isn't a more obvious reason why, taking the key off to check how it plays with the key off is a very basic test. Strange that no one else tried it before him. BTW if it was an old Selmer bass clarinet, many of those have a slightly stuffy low B regardless of pad (but not so much that you can't use the fingering!).

Lot's of cool FHE there! This thread should be manditory reading for new players and aspiring repair types(amatuer). I have no doubt that with all the info in this thread from all those in the know that getting my saxes in perfect(albeit vintage) playing condition.

Reguarding the stuffy hole, have you seen this article by MusicMedic.com? http://www.musicmedic.com/info/articles/num_47.html Seems quite intriguing, and might be practical. Just wondering if others had tried unusual fixes for this. As my playing progresses, I am sure that my vintage instruments will all more than likely have a similar condition.

 

[Steve]

There are alot of things that affect an instrument in many ways. years ago I researched and tested the body octave pip on my VII sax. You can read about it here
http://www.clarinetperfection.com/saxaqueaky.htm

Also, I believe it was clarinibass (?) here that had a more complete type experiment with a bass clarinets body register diameter opening (with replaceable pips). I had a copy of his experiment on my website but I can't find it which I think disappeared when I updated it a few years ago (something else to look for now).

But for repairers that keep searching for "why" a problem exists really helps everyone. I know with the VII some are considered "monsters" and some are really mpc sensitive. I also know why some mpcs don't work on some horns in relation to problems, and why sometimes the airstream seems like the problem. This one horn of mine really opened up my eyes in relation to mpc, reed, airstream, etc even though it took some time and experimentation.

 

[kymarto]

Another valuable test can be conducted with a stip of cigarette or other thin paper or plastic. Insert it under the pad at various points around the circumference and close the key--pull the strip out and note the amount of tension or "grab". You'll often find pads that do not seat evenly, and even if they will seal with pressure, that can seriously hamper the response and feel. This is also really good for reverse-sprung keys. It can't tell you much though, about small leaks caused by irregular or chipped tonehole seats or splits in pads.