Duplex noise

[Antares]

>I'm having trouble deciding what to do about front duplex sizzling noise I
>get on two Yamaha C-3. One is only 1 year old and the other is about 13. The
>older one I'm restringing now so the problem might go away. As for the
>other, I'm puzzled. If I mute the front duplex, then I loose too much
>volume. I know this duplex has a function, but the noise bothers me a lot.
>Has any of you found a practical solution to overcome this handicap? When I
>move the strings about, the noise sometimes will go and sometimes not.
>Should I mute only 1 string per unison? (I don't really like to see all this
>felt where it shouldn't be).

Hello Marcel Carey,


There are several ways to tackle this problem, but the simplest would be
to eliminate the buzz by voicing, otherwise one must remove all the
strings, the tuning pins, and lift the frame out of the instrument for
the problem comes from the underside of the da capo bar. It needs to be
filed and smoothed.

The origin of the problem is of course a mechanical one, (i.e. the
mechanics between the frame and the strings), but it is very hard to find
the right solution. We must also take into consideration that the strings
do have a specific place, the space between the unisons is more or less
conditioned by the hammer spacing, and the hammers by the whippens etc,
and the whippens by the keys.

Therefore, when we try to solve this problem, we must first make sure
that:

a. friction in center pins and between hammer rolls and repetition levers
has been minimalized
b. the regulation is perfect
c. the hammers have been filed beautifully and that each string in the
unison gets the same amount    of energy
d. the tuning is perfect

If this has all been done properly, then the instrument will probably
sound too loud and needs voicing.
Start voicing in the middle first, followed by the bass. When a good
voicing balance has been established, the "difficult" tones will be too
loud.
With the normal voicing procedure most of the "buzzers" will have been
eliminated, but a few will remain. With these, you must first check which
string of the unison causes the buzz.
Usually it is just one string or two. By voicing just that part of the
hammer, one "masks" the problem and it will not be such a nuisance
anymore.

Muting the front duplex will kill the tone, I am therefore definitely
against it, unless one note becomes such a hindrance that you will have
to do something about it (for instance in a studio during a CD recording.
In that case cut one balance punching in half, and with tweezers lightly
insert it in the front duplex unison. You can  slide it up and down a
little in search for the best result.

It is my experience that in every instrument there are some hidden
faults. They come out with age and sometimes even when the instrument is
brand new and has hardly been used.
What you described is one such problem and sometimes it is >just
impossible< to solve it.
In that case take into consideration that usually only the pianist will
hear the (slight) buzz, and that maybe the general quality of the
instrument, after having made the necessary regulation and tonal
improvements, is such, that a minor noise here and there doesn't really
matter that much anymore.

Friendly greetings

Antares