Just to add to what folks observe. I routinely observe this phenomena. I tune with my SAT, use two mutes and tune my unisons as I go. I kinda like that because I can easily observe my center string pitch to make sure it is stable. I tune Mr. center to the SAT, and then pull in my first unison. Often in that killer octave area I see the whole thing drop a tad on the SAT (go flat) and I think, hmmmm, did my center string drop or did this funky thing occur? I move my mute so that only the center string sounds and Walla - right back to pitch! This happens often. It sure seems real to me. And it definitely varies from note to note. Some notes will have no change, some a tiny little bit, and some a frustrating amount. Terry Farrell Piano Tuning & Service Tampa, Florida mfarrel2@tampabay.rr.com ----- Original Message ----- From: "Murray Seminuk" <seminukm@cadvision.com> To: <pianotech@ptg.org> Sent: Thursday, February 15, 2001 12:31 AM Subject: Re: ETD question re: unisons > Hi Roger > If you can audibly here that the note is out of tune with the octave after > all these attempts at tuning the unisons,then the note did not stay in tune > period.If the full blush of the Rct acts the same as the rotating lights on > the Sat ,I think that one does not have to look any futher.The unison can > only be tuned pure with the ear and good hammer technique.You also mentioned > that this is a newly strung piano. I don't think that this piano would be > very stable yet to do a test like this and produce any kind of results to > make any reliable assements.Keep on testing. > Regards > Murray > > ----- Original Message ----- > From: "jolly roger" <baldyam@sk.sympatico.ca> > To: <pianotech@ptg.org> > Sent: Wednesday, February 14, 2001 9:37 PM > Subject: Re: ETD question re: unisons > > > > Hi Muray, > > The test was done on a newly strung and hammered piano, > > regulation set with very close letoff. etc. Each string was sampled 10 > > times on the spectrum analyser to ensure the partials on each string were > > close. Also verified by ear. Each string was tuned several times for full > > blush on RCT, .01cent. The test was done with back and front duplex > scales > > muted. > > The piano was a really nice Steinway O. But I have have had similar > > results from my SD10. > > Several notes were done in this manner each showed a drop of 0.2 - 0.3 > cents. > > And yes you can just hear the shift when checking the octave. .3 cents is > > very audible within the unison > > To do this test all string temination points have to be in good condition. > > Ron is slowly winning me over, re a connection to either impedence, or the > > reverse, reactance. > > Some serious study of the principals of reciprocity is badly needed before > > we can begin to start to understand what is going on. > > Traditional piano thinking has been to look at the effect of loading with > > respect to the impedence of the board. Mechanical reactance (I think ) > > will be looking at the boards effect on the strings. > > They are not nessesarily the same. > > The subject is so complex that it would make a great PhD project. > > Good to hear from you. > > roger > > > > > > At 08:26 PM 2/14/01 -0700, you wrote: > > >Hi Roger > > >I'm really on a roll tonight , this is my 3rd reply.Correct me if I'm > wrong > > >,but are you saying that you tune each string a number of times with the > > >RCT,then take a reading of the three together and have a pitch drop of .3 > > >cents.I have been using a Sat for a number of year sand I find that I > cannot > > >always use the lights to tune a unison.I do not have a RCT to do a real > > >comparison but I find that when the lights stop there still is a "window > '' > > >to tune within.With my SAT a difference of .3 cents would be noticable to > > >the ear.I would wonder if all that has happened is that one of the > strings > > >is not in unison. > > >Regards > > >Murray > > >----- Original Message ----- > > >From: "jolly roger" <baldyam@sk.sympatico.ca> > > >To: <pianotech@ptg.org> > > >Sent: Wednesday, February 14, 2001 9:27 AM > > >Subject: Re: ETD question re: unisons > > > > > > > > >> Hi Howard, > > >> Yes it is easy to confirm. The test that I have done > > >with > > >> a RCT show about a 0.3 cent drop in octave 5/6. The test was performed > by > > >> tuning each string individually several times, to over come the > > >> interaction. then the net 3 string unison was measured. > > >> The effect is known as string coupling. > > >> My own theory is that. as all strings start to increase the amount of > > >> energy into the bridge, the board is moving through a greater > excussion, > > >> and hence dropping the frequency a tad. > > >> Now I've been out to lunch before, and I could be off base on this one. > > >> Regards Roger > > >> > > >> > > >> At 10:47 AM 2/14/01 -0500, you wrote: > > >> >Hi everyone, > > >> > > > >> >Since I know nothing about ETD's my question might be naive. > Nevertheless > > >> >here goes: I believe that Virgil's assertion that a 3 string unison is > > >> >flatter than each of the single strings heard singly, is a bit > > >questionable > > >> >or should I say not fully accepted. Wouldn't it be easy and conclusive > to > > >> >check this thesis by using an ETD to measure this? Thanks! > > >> > > > >> > > > >> >Howard S. Rosen, RPT > > >> >7262 Angel Falls Ct. > > >> >Boynton Beach, Fl 33437 > > >> > > > >> >hsrosen@gate.net > > >> > > > >> > > >> > > > > > > > > >
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