<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; = charset=us-ascii"> <META NAME="Generator" CONTENT="MS Exchange Server version = 5.5.2653.12"> <TITLE>RE: [CAUT] "D" with a ghost</TITLE> </HEAD> <BODY> We have 3 = "D"s here that have this "ghost" and does seem to come and go since the ringing wasn't always noticeable. = My guess is that it is fairly = common since 3 out of 4 of our "D"s have it. = We just keep a little bit of braid = on the offending duplex segment. <A NAME="_MailAutoSig">Eric Wolfley, RPT</A> Supervising Piano = Technician College-Conservatory of Music University of = Cincinnati -----Original = Message----- From: James Ellis [<A = HREF="mailto:claviers@nxs.net">mailto:claviers@nxs.net</A>] Sent: Wednesday, February 02, 2005 10:09 AM To: caut@ptg.org Subject: [CAUT] "D" with a ghost Another brand new D = has arrived in Knoxville, TN.  Some of us in the Knoxville Chapter = were checking it out at the dealer's prior to our regular meeting last = night.  I noticed a very prominent ghost-after-sound at = note C#-6.  None of = the other treble notes were doing this - just the C#-6. What first called = my attention to the C#-6 was its apparent short persistence, but = then I noticed the ghost sound when I released the key. The ghost was = persistent as well as pronounced, like a wide-open string somewhere, but no = dampers were hanging up, and none were seating poorly. We even checked to = see it the sound was coming from another piano (an open B that was sitting = side-by-side with the D), but it was not.  The whole body of the D just = seemed to resonate with that sound.  So, what was it? It turned out to be = the rear duplex of note C-4, whose fundamental was exactly on pitch = with the fundamental of note C#-6.  The muting braid stopped a few = unisons below that point in the scale.  The remedy was obvious, but I = suggested we just wait and see if anyone else notices this before anyone fixes = it. There is a good = chance that the ghost will come and go as the relative humidity changes = and the soundboard shifts, because that section of the duplex will be very = sensitive to it - more so than the speaking lengths of the = strings. This is proof of = what I have said so many times.  The vibrations of individual speaking = lengths do not couple across the bridge to their individual = duplexes.  They can't.  Instead, the vibrations couple all = up and down whole = sections of the bridge, to duplexes and speaking lengths = alike. Jim Ellis  = _______________________________________________ caut list info: <A = HREF="https://www.moypiano.com/resources/#archives" = TARGET="_blank">https://www.moypiano.com/resources/#archives</A></P= > </BODY> </HTML>