Yow-yow-yowing bass strings

[Nathan Bower]

This dosent really fit in with the wowing getting worse around a note, then
fading away again though. If it was something that happens in the
manufacturing of the strings, I would expect only those strings effected to
produce the yowing, not their neighbours.

N


----- Original Message -----
From: David Love
To: pianotech@ptg.org ; BobDavis88@aol.com
Sent: Friday, January 24, 2003 9:08 AM
Subject: Re: Yow-yow-yowing bass strings


Since it occurs irregularly, it would make sense to look at the string
manufacturing process.  My inclination (and I know you didn't want
speculation) is that it has something to do with how the wrapped portion of
the string is tensioned onto the core wire.  Too much tension, for example,
might cause the core wire to twist, or somehow become torqued in a way that
creates irregular or mismatched patterns when the string is set to
vibrating.  Since this problem seems to occur mostly in the heavier wrapped
strings, it may be because the thicker diameter of the wrappings in these
strings requires more tension in the horizontal direction while the string
is being wrapped.  The need for greater tension may tend to create more
variation in tension, simply put, it might be harder to hold it steady.  It
might be interesting to compare two strings, one that ! yows and one that
doesn't, off the piano by allowing them to hang freely and see if the yowing
one differs in terms of the amount of natural twist.

Just a thought.

David Love
davidlovepianos@earthlink.net


----- Original Message -----
From:
To: pianotech@ptg.org
Sent: 1/23/2003 6:58:17 PM
Subject: Re: Yow-yow-yowing bass strings


Thanks to those who have responded so far about this. I thought I'd better
send an interim response, so you'd know I'm still listening.

First, let me clarify what I know so far, and rule out a few things. I agree
with Ron that this is definitely not a voicing issue, nor a termination
issue. It's not in the leveling. It's not a leaky damper, nor an undamped
segment of another string. It's not in the hammer at all, or rather in the
angle of attack of the hammer (sorry Sarah, interesting post), since the
strings exhibit at least similar behavior when plucked; at least the yowing
ones still yow, and the clean ones are still clean. It seems to be in the
string itself, and consists of beats. What I really want to know is what is
beating against what, and while I really really really didn't want to
speculate, the hypothesis that seems most convincing to me so far was post!
ed by John Musselwhite:

"Would those problematic single bass strings have LMFs [longitudinal mode
frequencies] that are either unstable or out of tune with the rest of the
string?"

I have the CD from the Five Lectures, but I can't lay my hands on it right
now. However, my memory is while the longitudinal modes produce different
pitches, they are clear pitches, and not beating (?) Still, beating suggests
non-harmonic stuff beating with harmonic stuff.
-----
Well, I took a look at Conklin's patent on longitudinal mode design, and now
I understand more than I wanted to. It looks as if the longitudinal mode can
be tuned by controlling the weight per unit length of the wire, including
core and loading, and falls roughly in the area four octaves+  above the
fundamental pitch of the string. I still don't know for sure if this can
beat with the partials produced by the normal flexural modes, but I don't
see why not, and if so, I don't understand how you cou! ld reliably make
bass strings ever, especially if they are so sensitive that the same string
on the same model can come out either wonderful or hideous.

One of you scientists out there set us straight. I'm getting interested in
this, and I don't have time to be interested.

Bob Davis