Materials

has experimented for more than 30 years with heat treatment (including freezing), tapers, lacquers, thickness, and materials of horn metals. It can safely be said that any changes made to the material design effect the dynamics, response, and tone color of your instrument, not to mention its durability and resistance to corrosion. If you had to quantify how much the material affects the overall playing characteristics you might ask for our article entitled Acoustical Characteristics of Annealed French Horn Bells. To summarize, the hardness (or softness) as well as alloy effect the playing characteristics roughly a few percent. While this might not sound like much consider the results of a race car driver with a car that goes 185 mph vs. one which goes 189 mph. Following, we will discuss some of the more frequently asked questions regarding materials of brass instruments. To visualize how the material of your instrument vibrates, see below.

These are figures taken from an excellent article by Watkins and Bowsher, entitled "Vibration Characteristics of Brass Instrument Bells," published in the Journal of Sound and Vibration. These are 'modes' 1- 4 of a straight bell, no bracing. Each pair are opposites of each other and the bell would move between them at frequencies ranging from perhaps 20-30 cycle per second up to many kilohertz (or a thousand cycles per second), depending on the dampening of the material, how it's braced, the presence of a rim, a screw ring, lacquer, etc. You'll notice that the upper modes are vibrations mostly around the rim of the bell. It stands to reason that a garland would help to dampen some of the these, perhaps taking part of the 'edge' off the sound, but because it is really the internal elasticity of the material which governs the proportion of the amplitudes of each mode installation of a garland has limited effect. We've discovered that annealing just the rim works even better. The picture at the top of this page shows the pattern of the anneal. Other patterns can be used to cause various effects but the more complicated ones become expensive due to the time involved. Another frequently asked question or set of questions is how does freezing, lacquering or plating effect the instrument. There are objective studies already published on these and the answers are a little more involved than at first thought. Lacquers come in two primary varieties: natural and synthetic. With respect to an unlacquered horn, which we normally don't recommend as it lacks any protection from oxidation; the natural or air- dried lacquers have little or no effect on the instruments playing qualities. However, the synthetics, usually urethane, shrink during baking somewhat and can be expected to dampen the instrument about 3-5%. They are, however; easier to apply, look better and last longer so they are usually recommended for student instruments. Natural lacquer, while not lasting nearly as long, will still provide some protection for a couple of years so it is more costly to maintain. Freezing and other types of metal treatment have from time to time been promoted. Here again, the question,' Does it work?' , is not so easy to answer. We ran a study where a computer 'played' an instrument (ask for our article "Acoustic Primer" or consult Art Benade's terrific text book, "Fundamentals of Musical Acoustics," 1976, Oxford University Press, for how this is done and what the result's mean), both before and after freezing with liquid nitrogen. It was clear that the amplitude of the fundamental mode of resonance of the mechanical, not airborne vibration, had increased, but actually decreased for the upper modes. So it can be expected that freezing influences the mechanical vibration of the instrument's walls but does it have any musical significance? This is perhaps the most important question that must be answered. Even with all of our computer technology, a computer cannot tell you if something 'sounds' good. For a highly technical discussion of how we poll musicians and what musical attributes they seem to prefer, ask for our publication in the 'Journal of the Acoustical Society' on "Mouthpiece Correlations...". We have found through extensive blind testing that they seem to prefer a musical instrument with strong resonance but even playing resistance throughout its range; i.e., no weak notes or 'wolf' notes. Freezing tended to increase the vibration below the lowest note played so any effects are possibly 'felt' by the musician through his hands but there were no measurable differences in the airborne vibrations. Additionally, a former representative of the Copper Development Assoc. has claimed that in recent tests the crystalline structure of brass alloys reverts back to its original state over a period of time after freezing. What characteristics do seem to be important to the musician with respect to the material it is made of? It turns out that some things are more important from either a mechanical or acoustical viewpoint than others. We have found that heat treating in a 'pattern' so that parts of the bell are hard while others are soft considerably changes its resonant properties. Material as we've mentioned in other parts of this site, are equally important, which is why most of the horns we sell are made of bronze; although brass is also available. Link here for a brief audio demonstration at the bottom of our models page. Thickness and especially how it varies from throat to rim is also an important variable. Generally, a thin throat will give a quicker response but the dynamic range will be limited. This is a typical example of some of the compromises that are made whenever a bell is designed. Lawson uses a variety of engineering methods, especially modal analysis, to try and determine the best overall acoustic instrument but we also take into consideration the mechanical limits of the material and its resistance to corrosion. This is why we generally use bronze so that one of our horns should last through normal professional playing for at least 15-20 years. In fact, our first horns, built in 1978-1980, are just starting to come back into our shop for overhaul. For more information on material design please write or call.