Re: [Harp-L] Re: Harp-L Digest, Vol 133, Issue 22
Your reasoning is correct all the way down to your conclusion which is not:
Colder metal is stiffer. Correct but you may have over-estimated the magnitude of the effect.
Stiffness resists movement. Correct. Increasing the thickness of a reed near the rivet has the same effect.
However, a stiffer reed (e.g. thicker near the rivet) has a higher pitch.
On Sep 23, 2014, at 4:02 AM, Larry Sandy <slyou65@xxxxxxxxx> wrote:
> Interesting Vern. Thanks for that good information. I had reasoned the colder metal got, the stiffer it became, thus more resistance to movement ( which I thought would lower its pitch). Kinda like truck springs in sub zero temps feel stiffer than in summer heat.
> I think it was Richard Sleigh who explained to warm up the reeds while tuning so moisture build up on cold reeds doesn't influence the accuracy of the pitch.
> I am feeling lower pitched these chilly early mornings. LOL
> Lockjaw Larry
> From: Vern <jevern@xxxxxxx>;
> To: Larry Sandy <slyou65@xxxxxxxxx>;
> Cc: patpowers@xxxxxxx <patpowers@xxxxxxx>; harp-l@xxxxxxxxxx <harp-l@xxxxxxxxxx>;
> Subject: Re: [Harp-L] Re: Harp-L Digest, Vol 133, Issue 22
> Sent: Tue, Sep 23, 2014 9:18:33 AM
> If you cooled a brass reed by 20 degF, its pitch would INCREASE by about 1 centâ.imperceptible among the other variables affecting pitch. (derived from the chart at http://www.engineeringtoolbox.com/young-modulus-d_773.html ) Note that E (modulus of elasticity) decreases with increasing temperature and that pitch is proportional to the square root of E.
> If the pitch is decreased by moisture on the reed, the effects would tend to cancel.
> On Sep 22, 2014, at 5:36 PM, Larry Sandy <slyou65@xxxxxxxxx> wrote:
> > Pat, that's interesting. I have never heard that cold reeds are less flexible. That must translate into them playing a LITTLE FLAT until they warm up. I know cold reeds collect breath moisture quickly though, which would also lower the pitch. Interesting parallel. I wonder if cold, moist reeds are double flat? ð<br/><br/>Lockjaw Larry
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