Nicholas Drozdoff firstname.lastname@example.org
When I first began considering the ideas behind the sensibility behind using very heavy trumpets, valve caps or mouthpiece weights, I was skeptical about their efficay. However, as this page will show, I have rather drastically changed my position.
I originally got into a discussion group arguing about the merits of heavy valve caps. I was suggesting that the added mass of heavy valve caps should not particularly change the way a trumpet played as the mass was too far removed from the wind column. I felt that the added mass, if it was to change the timbre or response noticably, should be in the leadpipe or the bell.
I stopped in Wayne Tanabe's shop, The Brass Bow, one day and he convinced me to try a set of Curry very heavy valve caps on my Shew horn. I agreed to do a qualitative study comparing heavy caps to regular caps on the same horn. I was quite surprised by what I found. The upshot of this is that I not only ended up buying a set of heavy caps for this horn, I also bought a set of very heavy Warburton backbores for my mouthpieces.
Before we get into a discussion about why things work, let's discuss what actually happens. What I noticed first was the fact that the added mass caused the horn to "slot up" better - noticably so. I also felt that the extreme upper register responded much better. Finally, I found that my tone seemed richer in partials throughout the range of the instrument. All of these things seemed to be very desireable to me, so I went ahead and made the additions to my setup. I'm glad I did. I have had many nice comments from other musicians on the improvement in the sound.
There is one minor downside to doing this, however. While the horn "slots up" better, this means that flexibility becomes a bit of a challenge. For example, when doing a slow shake from a high D to a high E (in B-flat trumpet trumpet speak), it is a bit easier to do it smoothly without the added mass. It comes out with a more brittle feel with the added mass. However, with a bit of practice, one can make adjustments to the embouchure to make a smooth sounding shake even with the tighter "slots".
Now let's get to a theory of what is going on here. Let's recall what is happening when a sound wave is resonating inside of a metal wind column such as a trumpet. Let's say that we are playing a g on top of the staff at a forte. We have a standing wave inside of the horn. At nodes, the pressure is essentially constant and is roughly equal to the ambient pressure in the room. However, at the peaks or antinodes the pressure is varying wildly from a bit above the room pressure to a bit below the room pressure at the frequency of the note (g in this case). This means that the sides of the horn at the antinodes is getting "whacked" at the frequency of the note by the pulsating air. This certainly can cause the horn to vibrate. Particularly on lightweight horns we have all felt the instrument vibrating in our hands as we play it. All horns do this to some extent. Some more than others.
Now, if our playing a g causes the horn to vibrate, this means that some of the energy that we are putting into the system is going into shaking the horn rather into the sound coming out of the front of the bell as a musical tone. This is basically undesireable. While some of us like the informational feedback that we might get from feeling the horn vibrate in our hands your audience can't hear the horn vibrating. They'll just be able to hear the sound coming out of the bell. This implies that this is wasted energy.
Now the horn has resonant frequencies, just like the wind column. They are not necessarily the same resonant frequencies of the series for the trumpet itself, and that's good. If they were we might have some interesting problems. The resonant frequencies of the horn, or rather, the actual metal itself, depends on its shape and its mass. The greater the mass, the lower the resonant frequencies of the metal, the smaller the mass, the higher the resonant frequencies. So, by adding mass to the horn we are lowering its resonant frequencies.
Now we must consider, for a moment, what is happening when we produce a tone on a trumpet when we play. We are, by vibrating our lips, putting a rather funny pressure wave into the mouthpiece. The input pressure wave is not sinusoidal, but probably more of a square wave. In any case, there are many more frequencies that we are putting in than just the pitch of the note that we hear. The trumpet selects a certain collection of those frequencies (the overtone series of the trumpet) and allows them to build up as little standing waves as well. They are mixed in with the primary standing wave of the note that we perceive. This mixture of notes gives the trumpet its timbre. These extra notes are what we call the partials of the tone we are producing.
As a technical aside, another aspect of the growth of overtones or sidebands that show up come from the non-linear aspect of the trumpet. Without getting too technical let's just say that the non-linear aspects show up with the change in timbre of the instrument as you drastically change the volume at which you are playing. As one plays very loudly the tone is much brighter (more overtones). As you play extremely softly the tone becomes most flutelike (fewer partials). Enough on this matter for now.
What seems to happen is this: It is not just the note itself (the one we percieve as a pitch, g for example) but also the partials that go into shaking the horn. By adding mass to the horn we lower the resonance of the metal in the horn thereby not allowing it to vibrate on higher notes as well (this is a slightly simplifed overview here). Now, this means that the upper partials in our tone may not be able to shake the horn as well. This being the case the the energy that would have normally gone into shaking the horn must now stay in the wind column. This means more noticeable feedback support to our lips while we are playing. That is, the notes we play will resonate easier making our job easier. All of this also means that these partials are coming out of the front of the horn in the timbre instead of leaking out the sides. This will mean a tone richer in harmonics. This could be a good thing.
Now there is one caveat that I have ducked here. It is not a surprising notion to suspect that the metal in the trumpet will have resonance series as well. So if we lower the resonance of the horn we lower the resonance of the whole series, so it is still possible for higher notes to shake the horn. The trick is to shift the series of the metal down such that it doesn't line up with the series of the wind column very well, thereby reducing the tendency of the horn to vibrate as you play it. In a sense we are de-tuning the metal to keep the energy that we put into the system in the vibrating air column.
Now, why heavy valve caps? Well, the lead pipe enters the valve casing of the third valve. Some of the notes we play could produce an antinode at this junction, so this would be a hot spot. By adding mass here we can essentially "hold the horn still" there. Some players do this. They add a heavy cap only on the third valve. I prefer to use all three as the antinodes can move around throughout the tubing; i.e. the hotspots can move around.
Now originally I was suggesting that the valve caps are too far from all of these antinodes to make a difference, but I was wrong. They do,indeed, add sufficient mass to the system to cause the partials of the metal to line up differently with the partials of the wind column. I could definitely feel a striking difference in the "slotting" characteristics of the horn.
The next step in this thinking process was to get a sound sleeve for the mouthpiece. The logic here is as follows: There is always a big antinode in the mouthpiece. Therefore it is always getting "whacked" by pulsating air. It should be the biggest source of harmonic leakage. So, it seemed to make sense to "hold it still" by putting a big mass around it. I found that by using a Roger Ingram mouthpiece made by Black and Hill with a Warburton #11 heavy backbore (it has a big sleeve machined right onto it) on a Shew horn with the Curry caps, the horn responds extremely nicely. The only problem is the slightly more brittle flexibilty, as discussed earlier.
Now let's discuss what we mean by slots. A trumpet produces a series of tones at which it will resonate, sometimes called the overtone series. This means that the notes that we play come out easily, but if we try to play notes with the wrong fingering (not an alternate) it is very hard to do. Now if we try to bend notes we can only get so far before we trip up or down to the next note in the series. The farther we can bend the note before it trips, the wider the slot. If we can't bend the note very far before the note trips to the next harmonic, the slot is narrower. In engineering parlance we say the horn with a wide "bending range" has a lower Q (quality factor) than the horn with the narrow "bending range".
It would seem that by judiciously adding mass to a horn setup we are increasing the Q of the instrument.
Now for a little controversy. In an email exchange discussion one physicist suggested that the ideal horn for him would be one so massive that nothing you were playing could vibrate the horn. He was, it seemed to me, proposing a "maximum Q trumpet". This horn might speak very nicely on specific notes but it might be a bit inflexible as instruments go. Now, unless you're relatively new to the trumpeting business, the Monette name should be coming to mind. He is the guru of heavy horns. Now, I have always been skeptical of the notion of making a horn that weighs several pounds more than a standard trumpet, but after thinking things through a bit more carefully, I'd have to say the idea has merit. Of course, just making the horn massive alone will not make it any good. It needs to be machined with precision and built with tender loving care and attention to proper lengths and tapers to produce a series that is in tune.
Now I am not suggesting that one go out and spend $15,000 to $20,000 on a trumpet. That's up to you. What I am suggesting is that an extremely lightweight horn is not necessarily any better an instrument for playing, say, screaming lead trumpet than a heavyweight instrument. Don't forget, in the early days Maynard used to play a Conn Constellation which is a very heavy horn and sturdily braced. He could singlehandedly overwhelm the entire NY Philharmonic with one of these. Also, the converse could be asserted; a heavyweight horn is not necessarily any better for playing in a symphony orchestra or a chamber group than a thin wall instrument. Basically, this business of heavier horns is simply one more wrinkle in the tapestry of ideas shrouding the tradition of trumpet study.
One thought, at this juncture: it might be asserted that a heavy horn in chamber group allows the player to produce a tone rich in overtones at a lower volume, thereby making this a sensible possibility for the "legit" player.
In conclusion, I think it is safe to say that the old "physicists maxim" that one should be able to make a trumpet out of cream cheese and that nobody would be able to tell the difference in the playing characteristics or the sound is simply an outdated oversimplification of the facts. The nature of the metal (flexibility for example) and its mass make a distinct difference in the way the instrument plays that an expert listener can detect across the room.
Note: this is, of course, a qualitive discussion. I have not performed controlled experiments with drivers and frequency response measurements. I have simply experimented with equipment as a player. I have also referred to articles by Benade and Books by Backus and Rossing.
If you, as an expert reader, can find any oversights in my discussion, please use the email tags that show up at the top of each of my web pages to contact me with suggested edits and I will gladly try to work them in. If I do use your comments, let me know if I can quote you directly. Thank you. Nick Drozdoff
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