FW: Tuning Duplex

[atonal@planet.eon.net]

> 
> Hi Richard:
> 
> The Baldwin vertical hitch pins are positioned to enhance the duplex
> characteristics (well, almost). Since one of the three tail lengths must 
> go to a second hitch pin which is shared by the next note, only two
> strings per note will be in duplex relationship.
> 
> Jim Coleman, Sr.

> On Mon, 15 Jun 1998, Richard Moody wrote:

<snip>
 Now along comes Baldwin with the "acu-just" hitch pins. A bold 
concept as
> > a string riding that high on a hitch pin might cause tuning instability. 
> > However it doesn't. Now if these segments are not muted, might they be
> > considered part of a "duplex" if so are the acu-just pins positioned in
> > such a manner to enhance the duplex effect?  


	Actually, in my 8 years as Baldwin dealer technician, I've never 
found any sort of duplex relationship in the Accu-Just hitch pin 
system and the speaking length of the string. I tried three new 
Baldwin grands, an R 5'8", an L 6'3", and an SF-10 7', and the 'tone' 
generated by the tail portion of the string is all over the place in 
the three instruments. On some strings, there is a rough correlation 
with the fourth partial (ie: the same note, two octaves above), but 
it is so inconsistent, that is, it never occurs regularly, and in all 
three strings, that it can't be a design feature. I muted off the 
rear string section and played, and nobody discerned a difference, 
least of all me!  Also, the string heights vary on the Accu-Just pin, 
as it is meant to be an adjustable feature, so 'tuning' this section 
of string doesn't jibe with its function as bearing adjuster.

	Regarding stability of tuning, the string is extremely stable on the 
Accu-Just pin, as it is on the vertical plane in relation to the 
bridge, and the amount of back bearing between the bridge and the 
hitch-pin is not at such a sharp angle, the string stays put!   
However, today  I appraised a 1968 Baldwin L in a church, that has 
the conventional duplex 'plates' in front of the hitch pin (no 
Accu-Just at that time, at least not on the model L). The duplex was 
quite clear, an audible, consistent fourth partial relationship with 
the note played. Great instrument! Also, muting the duplex had a 
noticeable effect on sustain and fullness of tone. 

	Which brings me to my last point: the duplex section in front of the 
capo bar. I wrestled with a noisy front duplex section some months 
ago (the posts and replies are in the archives somewhere), and I came 
to the conclusion that regarding noise versus tone enhancement on the 
front duplex, you have to take the bad with the good. Minimizing the 
amount of capo bar 'noise' (ringing, sizzling, basically, non-musical 
craaaaaap!) involves muting the front section to such a degree that 
tone enhancement suffers as well. Muting off the section results in 
a noticeable decrease in tone, especially when playing up from the 
agraffe section to the muted capo bar section. The compromise I came 
up with was using flange bushing felt to mute the front duplex. 
Once the felt was woven through the duplex strings, the felt could 
be slid up and down the duplex until a balance was achieved voicing 
wise.  The felt was thin enough to allow some tone (and noise) to 
come through, but without the screeching harshness inherent in front 
duplexes. Best of all, it can be installed and removed in minutes.  

Regards, 

Rob Kiddell RPT
Edmonton, Alberta, Canada
atonal@planet.eon.net