Author: mschmidt
Date: 2007-04-28 03:03
The staples I have from Dunkel & Severson will sound a high (about 20 cents high) C# when the narrow end is closed and air is blown over the wide end. This is actually about what I expected! The addition of the cane should (a) increase the length and volume of the air cavity and (b) lower the pitch by resistance (reed too stiff) or loss (reed too unrigid--as in a flimsy heart, or having too long a tip). Thus a "good" reed is one where the excess volume and resistance/loss is minimal--about a half-step and 20 cents worth.
That's obviously not the last word in the theory of reed crows, but it makes me much happier with other people's insistence upon the C crow, because the C doesn't seem so arbitrary to me anymore.
Strangely enough, it also makes me ok with a below-C crow NOT resulting in a flat reed. (Which is my experience--I've had B-crow reeds sit up in pitch better than C-crow reeds, and, NO, I'm not compensating with my embouchre!) The B crow reed may just have more volume, or resistance, or loss...the pitch of the reed in the oboe is still being determined primarily by the interaction of the oboe bore with the reed--and that may be affected by other aspects of the reed than the crow is. Why would the reed respond differently in the oboe? Well, when the oboe is playing notes other than the C of the crow, the reed is being forced to vibrate at a different frequency. What's more, the different partials that are due to the oboe bore will also be present in the pressure function at the reed. So a reed that might be "lossy" when vibrating for the staple bore alone might not be so "lossy" when responding to the waveform of an A440 played on your Marigaux 901.
Yes, of course the embouchre is involved here, too, and some compensation can and will, be applied by the player. But even in the absence of the human factor, I believe there are physically sound ways of explaining (a) why a C crow is desirable and (b) why reeds not sounding a C crow can still play reasonably well (though perhaps not as well as a C-crow reed).
Mike
Still an Amateur, but not really middle-aged anymore
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