pipe organ pitch

[Don Price]

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Greg (and others who answered) - 

Thanks.   I believe you are correct.  Information I've received from a 
couple of other sources have indicated the change is closer to 2 cents, 
depending upon the particular pipes as you have stated.

Thanks for all you answers.

Don

Greg Graham wrote:

>Don, 
>
>Jonathan's answer struck me as too much.  I've checked
>pipe organs on 90 degree days and they were 30 cents
>sharp, not the 120 cents his formula would suggest.  I
>don't tune organs, but I measure their "A" pitch when
>someone at the church asks me to tune the piano to
>match the organ.  (No, I don't tune the piano 30 cents
>sharp on 90 degree days).
>
>Another complication:  flue pipes change more with
>temperature than reed pipes with short resonators. 
>Humidity impacts wood pipes, which increase in size
>with moisture, but not metal.  The various ranks do
>not move together.  
>
>"The Art of Organ Building" by G.A.Audsley, 1905,
>shows a table on page 637, "Vibration-numbers
>According to Diapason Normal at Different
>Temperatures".
>
>59 degrees F, A4=435.0  
>60 degrees F, A4=435.4
>... etc, etc
>67 degrees F, A4=438.5
>68 degrees F, A4=439.0
>
>I extrapolate this to A4=440 at 70 degrees F.
>
>"Diapason Normal" is the French law of 1859 specifying
>870 vibrations (really half a Hz cycle)per second at
>15 degrees C, or A4=435 at 59 degrees F.  This chart
>was intended to show where to tune at temperatures
>higher than "standard".  The coefficient used is
>interesting:  1/1000th of the frequency per degree. 
>435 Hz goes up to 435.435 at 60 degrees.  Multiply the
>frequency by 1.001 for each degree. 
>
>At A4, you're looking at about 0.4 Hz per degree, or
>about 1.6 cents/degree, theoretically, for open, metal
>flue pipes like a diapason.  Other stops will vary.
>
>Greg Graham
>Brodheadsville, PA
>
>  
>
>>pipe organ pitch 
>>jonathan stuchell jstuchell@verizon.net 
>>Sat, 03 Dec 2005 17:40:50 -0500 
>>    
>>
>
>  
>
>>hello,
>>    
>>
>
>  
>
>>6 cents per 1 degree F change ( expressly for a pipe
>>    
>>
>organ)
>  
>
>>----- Original Message ----- 
>>From: "Don Price" <dcp3@twol.com>
>>To: <pianotech@ptg.org>
>>Sent: Saturday, December 03, 2005 5:17 PM
>>Subject: pipe organ pitch
>>    
>>
>
>
>  
>
>>List -
>>Can any of you knowledgeable people tell me the
>>    
>>
>approximate amount of 
>  
>
>>pitch change in cents per degree of temperature
>>    
>>
>change for a pipe organ?
>  
>
>>Thanks.
>>
>>Don
>>    
>>
>
>
>
>
>		
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