longitude wave etc.

[Richard Brekne]

Hi Christopher

Putting a 7 foot Seiler in the context of your first post, along with 
your comments about Steinway instruments, I have to wonder if a less 
talked about (on this list at any rate) form of falsness is more 
accurately the diagnosis you should be after rather then horizontal 
frequencies. Tho to be sure I dont see the problem to be limited to S&S 
A-M's.... or Steinways and Seilers in general for that matter.

First, problems relating to horizontal modes are nearly exclusively 
related to the lower region of the piano and as Bernhard pointed out 
they have to do with a near coincidence of the lowest horizontal 
partial(s) with very high transverse.  More rare is when a horizontal 
nearly coincides with a soundboard resonanant frequency. I'm not sure 
I'd describe either as a

    "shimmery sound about 4 octaves above the fundamental and it
    "appears" shortly after attack"  that  "decays along with the rest
    of the sound."

tho. That description to my mind better fits a string that has either 
some kind of string noise present such as can occur from the speaking 
length front of the agraffes / capo when either of these are not 
functioning as they were designed to, or a string that has a falseness 
not characterized by the classic consistant period false beat. This 
falseness is often a wavery phase like with no distinct period, can 
either occur immediately at the attack moment or become apparent in the 
first bit afterwards and is very unsteady.  Careful string mating and 
voicing may help if indeed the problem is phasing that is impact induced 
but otherwise you wont get rid of the sound completely unless you 
increase stability at the terminations. I'm less then convinced we 
really know the mechanisms behind this falseness and the more talked 
about classic false beat, but I believe them to be closely related and 
have primarily to do with the bridge/bridge pin compound clamp 
termination / support and may even include the soundboard area 
immediately adjacent to the bridge at the affected area.  Ultimately, it 
is the soundboard that produces the airborn wave lengths that we hear, 
and therefore any out of phase behavior between the strings input at the 
bridge and this output sound will have high potential to create 
falseness, be they false beats with a distinct period, or this kind of 
unsteady shaky shimmering I am prompted to think of reading your 
description.  The only thing I know of that seems to have a positive 
affect on this are various schemes that essentially increase the 
massiness of the wood at the bridge pin. This can include the 
construction of the bridge itself, or the addition of stiffeners 
underneath or the addition of either CA or epoxy to the bridge pin 
holes. The cleanest and most precisely defined possible termination for 
the string also is a big plus in this regard. Bending the string around 
the bridge pin, as is often recommended has the opposite affect as it 
simply weakens the bridgepin / bridge compound support and introduces 
the potential for any small part of this compound termination to become 
springy in character. At some point that springyness will result in some 
form of falseness. The same can be said (and often is) for any 
aggressive string seating procedures.

Much of this has been discussed back and forth many times through the 
last 100 or so years, and the persistence of widely varied opinion 
underscores our lack of a real understanding on the subject.  We do know 
however that a few things seem to have a positive long lasting affect. 
So while a deeper understanding may be desirable, it is not strictly 
speaking needed to effect significant improvements.

Cheers
Richard Brekne



    Hello list,

        Many thanks to Berhard, Ron, Richard, and David-- all great
    suggestions and diagnostic routines.  I'll likely do very careful
    tests as the piano is a >10 year pristine 7' Seiler and I got in 
    quite deep with this person a few years back (acoustically
    isolating  the action rails.. it worked but neither of us were
    terribly  satisfied with the experience).   Also the sound is at the
    very edge  of my perception what with age and all.   Great things to
    try where  as before I had none.

        On the vein: ever since the first reading on longitudinal waves
    in  the PTG journal several years back,  I've wondered if there
    are,  occasionally,  rather pronounced problems in S&S models M
    through A   in the octave below mC.  These unwelcome sounds have
    been more  distinguishable and in the same four 8va above
    fundamental range.   I've always wondered why the owner/players have
    not complained...   I've never pointed it out to same.  Comments?

    Christopher Glattly

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