<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> 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: <blockquote cite="mid20051207144322.72993.qmail@web54612.mail.yahoo.com" type="cite"> <pre wrap="">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 </pre> <blockquote type="cite"> <pre wrap="">pipe organ pitch jonathan stuchell <a class="moz-txt-link-abbreviated" href="mailto:jstuchell@verizon.net">jstuchell@verizon.net</a> Sat, 03 Dec 2005 17:40:50 -0500 </pre> </blockquote> <pre wrap=""> </pre> <blockquote type="cite"> <pre wrap="">hello, </pre> </blockquote> <pre wrap=""> </pre> <blockquote type="cite"> <pre wrap="">6 cents per 1 degree F change ( expressly for a pipe </pre> </blockquote> <pre wrap="">organ) </pre> <blockquote type="cite"> <pre wrap="">----- Original Message ----- From: "Don Price" <a class="moz-txt-link-rfc2396E" href="mailto:dcp3@twol.com"><dcp3@twol.com></a> To: <a class="moz-txt-link-rfc2396E" href="mailto:pianotech@ptg.org"><pianotech@ptg.org></a> Sent: Saturday, December 03, 2005 5:17 PM Subject: pipe organ pitch </pre> </blockquote> <pre wrap=""> </pre> <blockquote type="cite"> <pre wrap="">List - Can any of you knowledgeable people tell me the </pre> </blockquote> <pre wrap="">approximate amount of </pre> <blockquote type="cite"> <pre wrap="">pitch change in cents per degree of temperature </pre> </blockquote> <pre wrap="">change for a pipe organ? </pre> <blockquote type="cite"> <pre wrap="">Thanks. Don </pre> </blockquote> <pre wrap=""> __________________________________________ Yahoo! DSL – Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com _______________________________________________ pianotech list info: <a class="moz-txt-link-freetext" href="https://www.moypiano.com/resources/#archives">https://www.moypiano.com/resources/#archives</a> </pre> </blockquote> </body> </html>