[CAUT] Duplex angle

[Alan McCoy]

Ric,

Thanks for your clarification.

I make a distinction between what I call string sizzle (buzzing at the capo)
and duplex noise. String sizzle I deal with by reshaping and voicing the
hammer, mating the hammer to string contact, reshaping the capo to get rid
of a groove. In that order. I deal with duplex noise by hammer voicing,
using pitchlocks in the segment, or glue on the offending string(s), and as
a last resort muting out the segment with a tiny fragment of bushing cloth
woven in that unison right up against the counterbearing bar.

To me the front duplex adds to the overall soundscape as does the
backlength. I have no objection to this when it works properly, in fact I
like it. But when a higher-than-normal harmonic in the duplex is excited and
stands out and annoys me, I try to deal with it. Same with string sizzle.
But they are different phenomena.

For me venue plays a role here. On a concert instrument in a larger hall, I
never mute out a duplex segment even if it bugs hell out of me while I'm at
the piano because I don't want to risk dampening projection. Unless it bugs
the pianist too.

Maybe we are ships passing in the fog here.

Alan


> From: RicB <ricb at pianostemmer.no>
> Reply-To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org>
> Date: Wed, 15 Nov 2006 21:25:33 +0100
> To: <caut at ptg.org>
> Subject: [CAUT]  Duplex angle
> 
> Hi Alan.
> 
> I dont really see that an experiment is necessary per se. Anything that
> comes in contact with the string only part of the time will cause a
> buzz... and suck up whatever energy goes into making the buzz.
> Conceptually... its the same thing as putting a penny on a unison and
> putting the string into vibration. Its just that instead of a free
> floating penny... its the edge of the capo / part of a groove / or in
> general poor contact.  The same thing would happen at the bridge if we
> didnt use bridge pins to hold the strings clamped.. yes ?
> 
> But if you must have some kind of experiment to demonstrate leakage
> across the termination, simply build yourself a monochord with the
> ability to alter the length and angle of the front duplex length. Then
> pluck the front length with some standardized force and measure the
> output of the speaking length.  You will find the angle and length are
> not nearly so related to this output as you might think.  On the other
> hand... there is indeed a clear and significant relationship between
> these same angle and length quantities as it relates to loss TO the
> termination (as in buzzing). And another clear relationship between
> these two along with the profile and hardness of the capo as it relates
> to long term wear... which can lead to buzzing over time... or string
> breakage... or other issues.  There is a lot to balance and the fact
> that there has been tried so many configurations attests to that.
> 
> Think of it this way Alan.  You have two things here.  Buzzing at the
> capo itself and a vibrating front segment.  Are they the same thing ?
> Of course not. I think the idea that they can be thrown into the same
> box came about because a group of techs not liking the front duplex
> sound as a whole decided to just define all sound coming from this
> system as noise.   This is clearly a misnomer because the definition of
> noise is along the lines of "random frequencies" where as the front
> segment is far too clearly defined.  And no... it does not matter that
> the actual frequencies deviate from the intended ones to some degree...
> there is a clear pattern and element of design to the front segment
> lengths. That simply precludes the idea of randomness.
> 
> Just as a kicker... I was on an old B today.  Just for fun I used a
> small pick to pluck at several front lengths to see what kind of output
> I'd get for the speaking lengths. Two agraffe's and two capos. You
> couldnt hear a difference in output at all.  Perhaps one is
> measurable... but the difference wont be much.  Angles up on the
> agraffes were about 15 degrees and the capo a bit steeper. Front lengths
> were standard at the capo for S&S and about 10 mm for the agraffes.
> 
> Hope this helps.
> 
> Cheers
> RicB
> 
> 
> 
>     OK. I hear you. So you must have devised some kind of experiment to
>     prove
>     this to yourself - that the buzzing that we hear is not excessive
>     leakage
>     across the capo, but is leakage to the capo instead. I'd like to be
>     able to
>     do that experiment myself. Can you describe your experiment so that
>     I might
>     be able to duplicate it?
> 
>     Alan
>