Pulsating string

[Jim Coleman, Sr.]

Hi Arlie:

There are several things which can cause a "pulsating sound from a plain
steel string. They all have to do with contact points. The termination at
the bridge is the most usual location. You have stated that it is solid at
the bridge. A question may be asked, "Is the bridge pin solid?" "Does the
string groove on the bridge surface extend beyond or in front of the bridge
pin?" Those are the usual problems at that end. Sometimes an over sized
bridge pin will solve this problem.

Strings can have an insecure termination at the Agraffe or V-bar. The better
rebuilders replace the Agraffes during rebuilding to avoid that problem. But
problems can also exist due to irregular shape of the string. As a 
string is pulled up and down thru the V-bar, a flat can be formed on the
string. Sometimes this flat may rotate slightly at its termination and cause
what sounds like "pulsating". The other cause of insecurity at the V-bar is
if the V-bar surface has a flat spot, where the string in motion bears upon
the front edge of the flat when it is up and it bears upon the back edge of
the flat when the string is in its downward excursion. Fixing the 
termination surface is the obvious answer in this case. Replacing the string
is the other answer. Of course, any time you change a string, you bring in
the insecurity of tuning for several months.

The third place where problems of this nature can occur is along the 
speaking length of the string. This can be a drop of glue on the string, or
contact of the string with the damper wire. A string moves in a vertically
oriented elliptical motion. This vertical motion can oscillate back and 
forth over a few degrees range so that it might contact a damper wire only
two or three times a second. It is simple to check visually for any damper
wire contact, just move the damper head away from the string and see if
the "pulsating" stops. If so, you need to adjust the strings or the damper
wire. Also visually inspect for any foreign matter on the speaking length
of the string.

Jim Coleman, Sr.


On Tue, 19 May 1998, Arlie D. Rauch wrote:

> The client has a very nicely rebuilt 85-year-old Hazelton Bros. grand.  I
> tuned it last fall and again recently.  She let me know a week later that
> she was not satisfied with the tuning.  So I went back.
> 
> The culprit was a pulse in the left string of the first unison immediately
> above the bass/tenor break.  It developed that she really was satisfied
> with the tuning, but she was hearing that pulse.  Apparently this problem
> has been there before, but she thinks that last fall the pulse was gone
> after I tuned the piano.
> 
> The string is firmly against the bridge.  The other half of the string
> which loops back to form the second string of the unison has a clear,
> straight tone.
> 
> Any suggestions as to the cause?  Any suggestions as to the solution?
> 
> Is it possible that tuning the piano to A-441 might have eliminated the
> pulse last fall?  Now it was tuned to A-440, both times per her
> instructions.
> 
> Thanks in advance.  I may not see the piano again until the end of summer.
> 
> Arlie
> 
> Arlie D. Rauch
> Glendive, MT
> 
> http://members.Tripod.com/~Turbooster
> 
> 
>