Duplex

[Ron Nossaman]

>>Not necessarily. A 2X12 plank across a 55 gallon drum will rock quite easily
>>with a kid on each end. It doesn't have to be a knife edge to produce the
>>effect.
>
>Agree entirely. However, to follow on from Johns comments, I suspect 
>that smaller radius bars produces less distortion. The 55 gallon drum 
>is an interesting analogy to the larger radius bar. The large radius 
>bar will actually cause the effective string length to shorten and 
>lengthen as the string goes through each cycle. I haven't proven this 
>by experiment, but it sure seems to have legs, if the bars (either 
>duplex or capo) have a large radius, the tone doesn't seem to be any 
>good. It changes radically for the better when the bar radii are 
>reduced.
>
>Ron O

Yes, the termination point will go back and forth with a larger radius, but
it will do something very similar with a smaller radius and higher bearing
angle. I wasn't worried about clarity of tone at this point. I'm still
trying to establish the mechanism by which string energy bleeds directly
across the capo and back with the front duplex, how the deflection angle
affects the process, and why the rear duplex doesn't work that way. That is
obviously still not settled. My illustration of the barrel and dome as
fulcrums wasn't relating to the radius of the capo, but as an illustration
that a larger contact area from higher bearing angles would still rock
across the capo. I didn't sufficiently explain that, and it apparently
wasn't a good example of what I was trying to convey. What I'm trying to do
at this point is to clearly establish some very simple fundamental
mechanical principals without a lot of confusing peripheral concerns that
come in much later, and largely as a result of these fundamentals.

Ron N