capo noises

[Wippen@aol.com]

Hello all,
I have been trying to catch up on my reading lately,and came across an
article in the Feb. Journal that brought together a discussion that took
place here on pianotech during the previous month (I guess?) .I had not at
that time subscribed to the list. In any event,the subject of the discussion
was capo d'  astro bar shape,composition, etc. and the "buzzs,zings,and other
noises" that emanate from the front duplex on many makes of grand pianos and
how those problems arise, with several ideas on how to deal with them.

I was surprised that no one mentioned that a significant reason for these
unwanted sounds is the lack of sufficient angle of the string as it passes
under the capo and rises toward the upper string rest. We all know that if
this angle is too severe,tuning and stability problems will result (witness
that un-tunable monster,the Steinway upright) ,not to mention the high
probability of string breakage and other gremlins.But, if that angle is too
small,I have observed that the capo section of the string *will* "zing and
jangle" Could it be that the speaking lengths vibrations are "leaking
through", causing its capo section string partner to vibrate. Yes, a grooved
capo will cause a buzz, and that buzz can often be eliminated by moving the
string back and forth under the capo bar thereby,I believe, burnishing the
bar a little, removing the little "hill" of iron that grew as the little
"valley" was worn in by the string.(That metal has to go somewhere). One can
also voice that noise down or out. That type of buzz is heard in the speaking
length more so than in the capo section.

I have a Steinway D at my school that had a terrible problem with these kinds
of noises. No amount of voicing,different hammers,shaping of the capo
bar,etc. had any effect on the problem. After numerous disappointments,I
began reviewing all that I had done so far to effect a cure. I occured to me
that when I did any shaping or filing of the capo bar I was actually changing
the angle that exists between the capo and upper string rest. If that angle
was too shallow to start with, then my work on the bar was exacerbating the
condition.

 As an experiment,and since I could think of no easy way to add metal to the
capo, I added individual pieces of formed sheet brass to each upper string
rest. The thickness of the brass was .016"-.020". These were covered with
felt and the piano re-strung. Result: NO BUZZES,ZINGS or Other noises.
There are no tuning problems,either. By increasing that angle I also
increased the length of the front duplex. Not much,I'll admit,but some.

 So it seems that either the increased length or the increased angle or a
little of both served to eliminate the unwanted noises. I have applied this
procedure to several pianos over the years, it always seems to work for me.
Hope this hasn't been to long, and that my rusty writing skills have allowed
my point to get across.

Paul Dempsey
Marshall University
Huntington,WV.
wippen@aol.com