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Some Thoughts on Pad and Resonator Design

15 Jul

We’ve been blessed in recent years to see significant advances in saxophone design made possible by a much better understanding of acoustics (I think I can honestly say that we now ALMOST understand what is going on inside the horn) and the use of new metal alloys. One area of saxophone design that I predict will show significant advances in the future is in pads and resonators. There have been a few what I consider to be “false starts” in pad design in the last twenty year, most of which centered around trying to re-invent the wheel and utilizing systems which were not compatible with existing key cups (requiring all new horns, or at least the very expensive replacement of the existing cups) or a radical change in installation technique. None of these alternative systems have gained any significant acceptance from either manufacturers or repair technicians. I really don’t foresee this situation changing in the future, believing that the pad of the future must be compatible with existing horns and existing technicians skills and equipment. There has been a trend towards the acceptance of “super premium” pads (Saxgourmet, ‘Roo, and Lucien Deluxe), and just as has proven true in the automobile tire aftermarket , there are always customers who will pay a premium in order to have the very best. The only significant advances in pad technology in the last twenty years meeting the above stated requirements has been the use of other leathers such as kangarooskin and goatskin rather than sheepskin, and the application of silicone based waterproofing treatments. I have always considered the silicone based treatments to be a poor choice for pads because although they are effective at sealing and waterproofing the leather, they quite often introduce a stickiness which many players find to be quite problematic. Goatskin has the advantage of being an extremely durable leather, available at a reasonable cost. Unfortunately, it tends to be somewhat grainy, and requires very vigorous ironing during installation to smooth out the surface flaws. Kangaroo leather is a wonderful material for pads. It is very strong and smooth due to the different cell structure of marsupials as opposed to mammals, and has excellent “drape” characteristics (the way the leather naturally hangs when relaxed), and does not stick to tone holes which are kept clean. Unfortunately, kangaroo leather is rather expensive, and there have been some very misguided efforts by animal activists to reduce its use, even though our friends “down under” without exception, consider their native ‘roos to be (1) a pest and (2) very good eating. We have used kangaroo leather pads exclusively in our shop for almost ten years now, and believe this leather is superior to all others in every regard. We take the additional step of ironing the pads during installation to tighten the leather, and apply our Teflon based Mojo’s Never Stick Pad Powder during the ironing process, which permanently imbeds the pad powder in the pores of the leather. Other than the leather covering the exterior of the pad, nothing has really changed in the design of saxophone pads in many, many years. Although better leathers have significantly increased pad life, there are other issues which I believe should be addressed: exterior size retention, felt stability, pneumatic leakage, and precise “feel” for the player. The quality of felt available today is such that there is no longer a significant difference (if you choose to avoid the cheaper grades and only buy “the good stuff”) between woven felt and pressed felt. Unfortunately, over time and with usage, all felt tends to shrink a bit and show some surface distortion. The key to achieving this stability is to prevent any long term changes in the shape of the felt disc which makes up the heart of the pad. We have had some success in achieving this stability through lightly spraying the felt (before pad assembly, of course) with epoxy. There is a fine line between not enough to achieve stability and an excess which significantly degrades the required flexibility, but the results can be quite good. Most saxophone pads in use today have a Rockwell hardness of around 40. Pre-treatment of the felt, used in conjunction with the naturally soft kangaroo leather, would allow pads of 55 – 60 in Rockwell hardness, which would contribute considerably to a very firm and precise feel for players. The issue which causes the greatest difficulty is felt shrinkage, and as longer lasting leathers such as kangaroo are used, it will be even more of an issue in the future. The solution to exterior stability has been around for many, many years, but unfortunately it fell from use due to high cost: a metal perimeter ring, beveled so the pad fits with absolute tightness to the rim of the key cup, and holding the leather taunt for the life of the pad. Of course, I’m talking about essentially bringing back a variation of the Conn “Reso-Pad”. Needless to say, this would be an expensive undertaking for any pad manufacturer, as unique tooling would be required ring for each pad size. Since most manufacturers make saxophone pads in half millimeter increments in sizes from 6 up to around 80 millimeters, you’re talking about around 140 different size rings (the very smallest sizes won’t need a ring), and before long, you’re talking about spending some real money! Pneumatic leakage occurs when air passes through the pores of the leather pad covering. All natural leathers are, of course, porous, but his problem is very easily dealt with by spraying the back of the leather with a light coating of vinyl prior to pad assembly. We’ve had considerable experience with this technique and I assure you it works like a charm! In order to give the pad a firmer and more precise “feel” when the key is closed, there is one final are that must be addressed: the back. Almost all modern saxophone pads use cardboard as a foundation. Of course, this foundation is somewhat less than rigid, so the pad has a bit of flexibility in the vertical axis. If this cardboard back were to be replaced with another material, metal or synthetic, a degree of stability which has been previously unknown could be introduced, improving the precision of the “feel”. In order to improve the function of the saxophone resonator, it is first and foremost necessary to understand exactly what a resonator is supposed to do. A resonator might best be thought of as nothing more than a mirror which reflects the wave back into the body tube. Of course, the most desirable quality of any mirror is accurate reflection of the submitted image, and to that end, the resonator should be made of the same alloy as the body tube if absolutely accurate reflection of the wave is desired. Any variation will alter the reflection and “color” the sound. This coloration may be desired by the player (using plastic or wooden resonators, for example), but I believe this to be a very dangerous practice because once the sound is altered by resonators, it is difficult to bring it back to its original characteristics. In my opinion, a technician should never “paint a player into a corner” by changing this fundamental aspect of a saxophones sound when numerous other options such as necks and mouthpieces are available. The size of the resonator is absolutely critical to maximizing the performance. Basically, the greater the surface area of the resonator, the greater the degree of reflectivity. To this end, it is desirable to reduce the amount of exposed pad leather. Put another way, the optimum resonator will extend all the out to the edge of the tone hole chimney. Before proceed to the next aspect of resonator design, I must make a confession to my readers: I slept through most of high school geometry. That being said, I do recall that something was mentioned about a domed surface having a larger surface area than a perfectly flat surface if the diameter of both surfaces was the say. Armed with this knowledge, we have devised resonators of progressively larger surface area by constructing them with domes, cones, ridges, and other appendages. I believe that the optimum shape may be in the configuration of a conical nautilus, and hope to construct some resonators in this configuration soon in order to test this theory. Of course, it is essential to seal the resonators at the edge and around the hole through which the attachment device (screws are far more desirable than rivets, as this allows the costly resonators to be reused) passes. This is easily accomplished by having a lip around the perimeter of the resonator which “bites” into the leather and provides an air tight seal. Of course, all of these improvements would by necessity come at a monetary cost. This cost would probably be far higher than the average player would be willing to pay. However, remember that if we restrict advances in technology and design to the pocketbook of the average consumer, Rolls Royce would have gone out of business years ago! I would be most interested in your comments and thoughts on these matters, or anything else related to saxophone design. My email address for your comments and suggestions is saxgourmet@cox.net, and my office telephone number is 504-324-3850.

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