ETD question re: unisons

[Farrell]

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
> > >> >
> > >>
> > >>
> > >
> >
> >
>
>