<!doctype html public "-//W3C//DTD W3 HTML//EN"> <html><head><style type="text/css"></style><title>Re: Duplex</title></head><body> <div>Dave and Duplex-Dan,</div> <div><br></div> <div>Dan wrote:</div> <div><br></div> <blockquote type="cite" cite>. . . The duplex can be way out of tune and many pianists as well as audience may<br> not mind.</blockquote> <div><br></div> <div>Similar to some concert tunings and CD recordings. And sure, a number of pianists are just 'key pushers' and similarly with regard to audiences, many will be cloth-eared. But there will always be a couple who can hear.</div> <div><br></div> <blockquote type="cite" cite>Your note does include an interesting idea that has been used successfully by</blockquote> <blockquote type="cite" cite>tuners who tune duplex scales.</blockquote> <blockquote type="cite" cite>The idea of "massaging" the duplex scale.</blockquote> <div><br></div> <div>Yes Dave well said. But it has been mentioned on this list before. Maybe you weren't paying attention DD.</div> <div><br></div> <blockquote type="cite" cite>Basically what this is is stretching, as when putting new strings on a<br> stringed instrument. This does bring the string down and provide a stretch</blockquote> <blockquote type="cite" cite>and evenness to the string .</blockquote> <div><br></div> <div>I don't agree - I've gone through this all before on the list - twice at least.</div> <div>What if the duplex tension was low and the block too close to the bridge also, causing the duplex pitch to be sharp even though the duplex tension is low? Will rubbing the duplex segment to tune it by lowering its pitch 'provide a stretch and evenness' as you put it? No - by rubbing the duplex length in this situation to tune it, the duplex tension would be rubbed down to be even lower in tension, relative to that of the speaking length. If the situation as described<font color="#0000FF"> (at paragraph start)</font> were to occur, assuming that the duplex and speaking length were in fact tuned at the previous tuning by rubbing and not moving the block, the speaking length would creep flat as the duplex went sharp<font color="#0000FF"> (since the duplex tension would be lower)</font>. This creep would gradually occur since the changing dimension of the hygroscopic bridge cap, which causes the strings to rise and fall while in contact with the bridge pin<font color="#0000FF"> (as Ron N so beautifully described in his Reno bridge class)</font>, would encourage the string to creep across the bridge cap slowly in an effort to equalise the tension on either side of the bridge<font color="#0000FF"> (you see Ron N, while you were discussing vertical bridge movement in your class and its predisposition to falseness, I was thinking off topic about its relevance to the way in which string creep occurs when the string segments aren't at uniform tension - I had previously understood the reason, but not the facilitating agent for string creep at the bridge - and no, DD, creep will not occur around the hitch pin since the steel hitch pin is not hygroscopic)</font>. This would cause the duplex to go sharp and the speaking length flat. This would tell us that the block is too close to the bridge.<font color="#0000FF"> Is that all as clear as mud in a beer bottle now?</font> You see, if you were to rub the duplex to lower the pitch without moving the block, the unequal tension would in this case be made more unequal. Hence the tuning stability would be worse not better. On the other hand, since we determined that the block was too close the bridge, when we move the block away from the bridge, the duplex pitch drops maybe going through pitch to flat, then we rub the speaking length to bring the duplex up into tune. What happens if we move the block too far away from the bridge when we adjust it. Well when we rub the speaking length we will have to rub too hard to get the duplex up, causing the duplex tension to be too high even though it is in tune. During the inter-tuning period, the reverse will occur, the duplex will go flat while the speaking length goes sharp. What do we do then at the next tuning<font color="#0000FF"> (when we find out that we stuffed up last time)</font>, we move the block back in closer to the bridge, by what we hope is about half of the original adjustment. And on it goes - incremental refinement is the name of the game.</div> <div><br></div> <blockquote type="cite" cite>But as to the application of this stretching to</blockquote> <blockquote type="cite" cite>a tuning job, I can not recommend it if it is used in lieu of placement of</blockquote> <blockquote type="cite" cite>the harmonic bridge.</blockquote> <div><br></div> <div>Yes and no! Massaging the string cannot be used in lieu of moving the block, or vice versa. The two procedures must be used together as described in the previous paragraph, with an understanding of what's actually happening regarding the string tension on both sides of the bridge. But it should ideally be done at the time of a subsequent tuning. In my experience, it is necessary to return to a previously tuned piano (and I mean tuned with a proper hammer technique - not a tuning where the 'tuner' is swinging the pitch all over the place like a flag in a breeze), in order to fully understand where the string segment tensions and the block positions are at. It is when the piano is subsequently retuned after a solid and accurate tuning that we get to understand which blocks are positioned correctly and which they are not - by reading the string creep across the bridge. When the bridge creep ceases, and it will eventually if the designer and builder have done their bit properly, you know you've finally arrived. That is, provided that the piano scale was designed in such a manner that the percentage of breaking strain is uniform from note to note - provided that the information was transferred accurately from the CAD drawing to the real world piano, then the piano just might stay in tune - provided that hammer technique . . . . . . .provided that the pin block is  . . .provided that. . . Isn't this fun !!</div> <div><br></div> <blockquote type="cite" cite>The duplex portion of the string is comparatively short and the most<br> effective method of tuning this segment, and having it stay in tune is to</blockquote> <blockquote type="cite" cite>adjust the placement of the harmonic bridge (duplex) to a point on the plate<br> that promotes a fundamental duplex tone that is in harmony with the speaking</blockquote> <blockquote type="cite" cite>length.</blockquote> <div><br></div> <div>From my experience, yes and no. Sure we want to achieve an in tune duplex segment, but moving the blocks alone won't get you there with stability. You cannot achieve tuned duplex stability by moving the blocks alone without also massaging the wire (on whatever side of the bridge is determined to be appropriate). It would not be possible to just move the blocks around to achieve a tuning of the duplexes, without also taking stock of what's also happening with regard to duplex tension. One cannot just use a simplistic approach to this stuff. Paolo Fazioli was the first person to bring tuning of the duplexes to my attention back in 1994, when I spent days at the factory with Hiener Sanwald discussing this and many other matters. I believe that it takes experience doing it combined with a modicum of thinking it through, when working with duplex tuning to understand what is happening. If we are going to discuss this stuff, then let's think through what is actually happening DD. It was only a couple of weeks ago when you were calling  the front-detuning fraternity the naysayers, not a particularly helpful turn of phrase perhaps. Well I can tell you DD that some of those 'naysayers' have thought about this stuff for years as I'm sure you have too, and some of them have even gone to the trouble of building pianos of their own, after rebuilding everyone elses stuff for about fifteen years for a backgrounding - while modifying the manufacturers products all the while to prove or disprove a point.<font color="#0000FF"> (Steinway Hamburg seem to have heard of our little 'workshop of ill repute', judging from some of the grapevine comment that has returned over the years, and their threats of legal action for modifying their precious designs. Once in 1996 I was accused of using non-Steinway agraffes in a D, but they were Steinway New York agraffes instead of Steinway Hamburg - I had tried to get Hamburg agraffes but the relationship had gotten so frosty with Hamburg that the local dealer wouldn't supply. I never did get to tell them what really happened, but then again would they have listened? - talk about the left hand not knowing about the right hand)</font> Anyhow, so called enquiry can come occasionally with its unwanted pressures, even if we are only involved in the tiny piano industry - I digress. Furthermore DD, some of those 'naysayers' have deliberately sought out folks who disagree them along the way so that they might, together, slog it out to reach some sort of truth - though occasionally only a truce. Several months ago John Hartman and I had a disagreement on this list, in which it became obvious that we both had very different yet strongly held views about bridge capping. Now, after further reading some of John's Journal articles on other topics, I have come to understand that he is a very knowledgeable technician. Sure there are differences in approach between us which are still very much I suspect as they were, but I would very much like to have a frank and friendly discussion with John at some future time - it would be interesting I'm sure. We don't have to all agree, but at least we should all think about why we think the way we do. Let's at least think about the parameters we are dealing with here before taking off irretrievably on our particular tangents. You never know, sometimes we think we're saying something different, when closer attention can reveal that occasionally, two different folks can be saying the same thing from opposite sides of the fence (or the ditch), without realising that there are more similarities than differences. I'll shut up now - keyboard's due for an oil change.</div> <div><br></div> <div>Hey Terry, how's that jpeg coming along? Yes Ron N. soon I'll compose a draft on the pare.</div> <div><br></div> <div>Ron O.</div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div><br></div> <div>-- <br> Overs Pianos<br> Sydney Australia<br> ________________________<br> <br> Web site: http://www.overspianos.com.au<br> Email:     mailto:ron@overspianos.com.au<br> ________________________</div> </body> </html>