<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Duplex</title></head><body> <div>At 2:48 AM +1100 11/10/01, Ron Overs wrote:</div> <blockquote type="cite" cite>JD wrote:<br> <blockquote type="cite" cite> > Well, Ron, this presumes a pretty sharp "terminating pivot" which is neither <blockquote type="cite" cite> desirable nor even attainable by makers who might think it desirable.</blockquote> </blockquote> </blockquote> <blockquote type="cite" cite><br> It's certainly attainable JD if we want it. Bars can be hardened to cut piano wire like cheese should one desire it. And that without as much as marking the bar.</blockquote> <div><br></div> <div>Sure... such stuff as tuners' nightmares are made on!</div> <div><br></div> <blockquote type="cite" cite><br> Ron N replied:<br> <blockquote type="cite" cite>Not necessarily. A 2X12 plank across a 55 gallon drum will rock quite easily<br> with a kid on each end. It doesn't have to be a knife edge to produce the<br> effect.</blockquote> </blockquote> <blockquote type="cite" cite><br> Agree entirely.</blockquote> <div><br></div> <div>Well the all the 55 gallon drums on the pianos I deal with are cemented to the frame and have the 2x12 plank firmly clamped to them by the upward pressure on the plank and I challenge any kid to use them as a see-saw.  The analogy doesn't hold water!</div> <div><br> <br> </div> <blockquote type="cite" cite> However, to follow on from Johns comments, I suspect that smaller radius bars produces less distortion.</blockquote> <div><br></div> <div>I would say that the smaller the radius facing the speaking length the better, just as a short vertical drop in the soundboard bridge in the line with the centre of the pins will provide the best termination there, but since I am not interested in resonant front lengths I would provide a relatively long sliding surface to the plank side at the same angle as that made by the wire as it rises to the bearing bar.</div> <div><br></div> <div><br></div> <div align="center"><img src="cid:a05100303b811d024b97e@[195.147.149.106].1.0"></div> <div align="center"><br></div> <blockquote type="cite" cite>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.</blockquote> <div><br></div> <div>Yes. in effect the string never knows how long it is and there will be minute fluctuations in the frequency together with the risk of noise.</div> <div><br></div> <div>When I am restringing pianos without duplex scaling, eg. Ibach, Bechstein, I usually replace 'soft' bearings with a 1/8" round or half-round bearing backed up with a softish felt bearing, sometimes adding a second 1/8" brass bearing before the wrestpins.</div> <div><br></div> <div>JD</div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> </body> </html>