Re: Re: can-o-worms


[ Follow Ups ] [ Post Followup ] [ TubeNet BBS ] [ FAQ ]

Posted by Rick Denney on November 13, 2001 at 12:02:29:

In Reply to: Re: can-o-worms posted by John Swensen on November 12, 2001 at 13:19:15:

My response to Joe's observation is lower down, but first I want to address something John said.

John, I was right there with you until you talked about a "big tuba with a fundamental-rich dark sound." In my own testing, it seems to me that a big tuba has a full, deep sound, but that the sound is actually quite weak in fundamental. A smaller tuba playing the same note might actually have a similar amount of energy in the fundamental, and less in the higher harmonics. My Yamaha 621 has much less energy in the 8th through 12th harmonics than does my York Master, even though both are similar in the lower harmonics.

Part of the problem is that "big" and "dark" are two different effects. To me, dark means rich in fundamental, and big means ever-present, or impossible to bury (which does not mean loud or cutting). I have heard great players on rotary tubas with the tall bell stacks and small flares that were extremely dark, and I have heard the same players with a sweet, bottomless-perhaps-but-not-merely-deep sound that excites descriptions such as "colorful." It seems to me, therefore, that the essence of the wide-belled sound is a lot of high-harmonic color. Our ears interpret that color as depth, because it is ever-present and impossible to bury, seeming to float under the orchestra. But that depth may be an interpretation based on the spacing of strong higher harmonics. Certainly, the higher harmonics were stronger in my York than in my Miraphone.

A tuba player making a good sound is lining up all those harmonics so that they build on each other rather than sucking energy from each other. My teacher demonstrated just this to me during my last lesson.

Intonation cues, on the other hand, seem to come from the spacing of those harmonics and how they interact with other tones in the ensemble, just as you describe. We agree on that point.

But that brings up what seems at first glance a paradox: If a wide-belled tuba produces a lot of higher harmonics compared to a narrow-belled tuba, then it should be the wide-belled tuba with the greater sensitivity to intonation. But that is the opposite of Joe's observation.

I think the answer is not in the harmonic structure as much as it is in the propagation of sound. A tall bell stack with a flare resembling an exponential horn will be directional, and will therefore point the sound most strongly along a particular path. A relatively short, wide bell flare and taper resembling a bi-radial horn will be much more omnidirectional, with the sound less strong in the central path and stronger in the peripheral paths. Therefore, the listener will be hearing sound from the latter instrument after being reflected through a larger variety of paths, each of which will be a different length. Therefore, the phasing of the sound waves along those different paths will be more varied with the more omnidirectional instrument, and I think that will confuse the sense of pitch somewhat. The sound from the more directional bell will be more represented by the central path that it follows, with less colaration from differently phased alternate paths.

Thus, a wide-belled Distin can have more of the characteristic Joe observes even though it is smaller than the narrow-belled Cerveny mentioned elsewhere in this thread. And a Getzen G-50 or Conn 56J can have that classic American sound even though they are not particularly large instruments.

Rick "who thinks Joe's observation would be less noticeable in an anechoic chamber" Denney


Follow Ups: