Text: From: linnstaedt@aol.com.geentroep (Robert Linnstaedt) To: rolls@foxtail.com Date: Thu, 6 Apr 2000 08:47:48 EDT Subject: Free Reeds and Beating Reeds Johan Liljencrants writes in Digest.00.04.03: > 3. Inward beating reeds, as found in the oboe, bassoon, clarinet, > saxophone, and organ reed pipe. The wind supply tends to _close_ the > reed passage. The frequency is complexly related to the natural > frequency and is also much dependent on pressure. Inward beating > reeds are used with a resonator, and the coupling of the resonance to > the downwind side of the reed is _strong_ because of the large exposed > reed area. The reed is dominantly a _stiffness; [load? resistance?] > the tone fundamental frequency is slightly _lower_ than the natural > for the reed, it is dragged down by an additional air mass in the > resonator. > > Hopefully these distinctive features tell why inward beating reeds > are the ones used for pipe organs. Basically low pressure is needed, > and high feedback (high coupling) from the resonator. A discussion > about this reed type only will follow. This was most fascinating, as I am both a reed organ restorer and professional oboist. I came away with a completely different concept of the underlying principals which cause the various types of reed behavior. (What kids call a "well, duh!" experience). On observation, I would have expected free reeds to exhibit a nature combining the two types of beating reeds since the tongues relation to the frame places it first upwind and then downwind through its full cycle. I hope Professor Liljencrants in his next discussion can include a word about cylindrical vs. conical resonators. I have wondered at the "why" behind their special characteristics and how one causes the nodes to aggregate at one end only. Regards, Robert Linnstaedt

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