[CAUT] pre-stretching new string?

[Don Mannino]

Mark,

I agree with much of what the others have said.  String elongation is
pretty much an instant event, and if the string is stabilized well very
little further "stretch" takes place.

I agree with others that the string coil is a big factor, and it has
been my impression that raising the string 1/2 step when first
installing it, then keeping it there for some time (from 15 minutes to
1/2 hour), then playing hard while finally lowering the string down to
pitch will cause the tuning pin segment to equalize in tension with the
rest of the string.  Working the coil in some way is a good idea as
well, as long as you do not scratch or nick the wire.  If the coil is
initially pulled a little high, then the coil is tapped down after the
string is up to pitch, the coils will stabilize as well.  Just don't
nick that wire!

The Kawai factory does the first chip tunings to 1/2 step sharp, and as
others have noted, the piano will usually be a little flat at the end of
the chip tuning.  After a week's settling, the piano is chip tuned again
to A=445 (19c sharp).  After the action is fitted the piano is pounded
by a playing machine for 15 minutes, then tuned again at 445.  It is
then pounded by a playing machine for another 15 minutes, and tuned
again to 445.  Finally, in the voicing department it is tuned to 443.

For individual _plain wire_ strings, I have done many a string just
before concerts and had great luck with the following process:

- Install new wire, seat becket and hitch pin loop, raise tuning pin
coils very tight, pull to +100c
- Squeeze becket and tap tuning pin coils down lightly, repull to +100c
- Squeeze hitch pin loop, lightly tap strings behind and in front of
aliquot.
- Lightly tap strings behind bridge and in front of bridge at an angle -
not down, but in towards the bridge pin.
- Hook wire up by the capo / agraffe in the speaking length.  Also
stroke wire up in front of the capo / agraffe, if possible.
- Tap string down on either side of the front counter bearing.
- The pitch should be close to correct now, but still sharp.  Pull it
back to +100c
- At the latest time possible - possibly as the doors open for the
audience - tune the string down to pitch while playing it hard. Settle
it well, then recheck the octaves for about 5 or 6 notes above and below
the new string.  Check hammer mating to the new strings and hook again
as needed, then do the final tuning on the new string.

The last time this happened to me was during the final tuning touch up
40 minutes before a concert at the University of South Carolina in
Charleston a couple of years ago.  I rechecked the unison at
intermission and it had not moved.  The next day I checked it after the
piano had been moved, and the unison was still good - very slight meow
in it (and in others elsewhere).  After the piano got back to Kawai a
month or so later that string was no more out of tune than the others
around it, but I'm not sure if the piano had been re-tuned in the mean
time.

Someone mentioned that the string bends move, and this is true - but
they do anyway under normal circumstances.  If the bridge and aliquot
bends are settled while sharp, and the capo bar bends are settled when
close to the final pitch, then the bends will not move enough to create
tonal or stability problems.

One last note - I remember Franz Mohr saying that he would raise the new
string a whole step (200c) sharp.  This kind of scares me, but I guess
it worked for him.

Don Mannino
 

> -----Original Message-----
> From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On 
> Behalf Of Mark Cramer
> Sent: Tuesday, June 05, 2007 12:22 PM
> To: CAUT
> Subject: [CAUT] pre-stretching new string?
> 
> In last month's discussion of wire stretch, someone mentioned 
> pulling a new string a semitone sharp to take care of any 
> future stretch along all its segments.
> 
> Is a 'semitone' overpull common practice for new (plain-wire) strings?
> 
> Would you do this as part of a full re-stringing as well, or 
> is this just a habit when trying to get a new single-string 
> replacement stable?
> 
> I've never done so, but can't see the harm with fresh new 
> wire. Anyone want to educate me on the subject?
> 
> thanks,
> Mark Cramer
> Brandon University
> 
> 
>