Crafting a Better Horn Sound.
The horn is a delightfully complicated instrument. I remember once Rick telling me that he asked an acoustician to explain how hand stopping worked and the person offered a half hearted explanation followed by “but we don’t actually really know”. I also recall a conversation with George McCracken (who was friends with Arthur Benade) in which I asked him how he designed his tapers. His answer was “come up with something, cut a mandrel, and try it out”. As much as we would love to have some magical ways of designing horns, we’re sort of all just stumbling around hoping to find something to work. It’s one reason that I believe hand makers can still compete with companies like Yamaha who have banks of engineers working on designs. It’s also a reason why I roll my eyes every time someone comes out with a new “the best lead pipe ever”.
While we may not completely understand exactly how horn acoustics works, crafters who work exclusively and intensely with the instrument can begin to intuit some things that seem to happen over and over, and classify some conditional effects that can be used to exert some control over how the instrument plays. As with many other aspects of horn making, it’s a bit more complicated than simply stating the less bracing is better, or that a lighter horn is more responsive (neither of which are true).
Here is one way I explain how a horn sound is created: imagine that you can produce ten units of buzz energy with your chops. Two things happen to this energy, one is that a standing wave is created inside the horn, out the bell, into the hall, and into the listeners ear. The second is that the physical object of the horn (brass, nickel, solder, your hand, the flesh of your lips, the contact between the mouthpiece and lead pipe) vibrates, creating heat, mechanical friction, etc.
If only ten units of buzz energy are available in the system, the horn splits the energy in some ratio between the standing wave and the mechanical motion of the metal. This is important because of each motions effect on the sound. The standing wave is made up of pitch specific frequencies and are determined by the taper of the tube which delivers pitch information to the listener (think classic overtone series). The other frequencies are non pitch specific and are based on the temper and thickness of the metal, as well as the space between braces and brace patterns on the valve section (along with a gajillion other things).
The ratio between the pitch and non pitch specific frequencies are what I refer to as “acoustic density”. The more dense (more pitch specific frequencies) the horn is, the more power and projection the horn has in the hall. The less dense (more non-pitch specific frequencies), the more color the tone has and the better the horn sounds up close. This is why some very powerful horns are said to have a laser like quality (not enough color), while some horns that physically feel “alive” sound great up close but lack power and have intonation issues.
There is no clear proper acoustic density for a horn. Each maker (knowingly or not) changes how the horn uses your buzz energy by their choices of temper, joint techniques, brace patterns, among others. The better a part is made, fit, and installed, the thinner and longer the bead of solder can be; adding density without dampening from too much solder. It’s yet another example of why good craft makes better horns and why two horns that look the same can be so different. A Medlin horn may look like other Geyer style horns, but that’s where the similarity ends.