At 01:57 -0500 10/03/2011, George F Emerson wrote: >...I suspect that, at that time, they did not have an adequate >understanding of the effects of longitudinal mode partials, or how >to calculate their frequencies. It is correct the longitudinal >mode is not affected by tension. Thank you for your informative post, Frank. Thatˆs roughly how it appeared to me. Iˆm not sure Iˆve ever seen a formula for calculating the longitudinal frequencies. Have you got such a formula_ >...usually on the low side of the 20 KHz limit. That being the >case, how can it be that longitudinal partials are so significant in >that range of the piano's scale, where they are inaudible to the >human ear? This is not to discount the phenomena of what is called >a whistling sound in the upper range of the piano, but rather to >attribute it to the transverse modes of vibration in the >non-speaking segments of the strings, not the longitudinal modes of >these segments. Yes, thatˆs what I, and presumably a lot of other people, have always assumed˜ hence my surprise at what I read in the patent. >The longitudinal mode is of more significance in the bass range of >the piano, but that is another subject. So far as I remember this was the area Conklin was concerned with, so much concerned that he designed a very complicated bass string making machine to produce strings with predictable longitudinal frequencies. I doubt if it was practical, having seen the design, but thatˆs another matter. >Most "modern" thinking is that duplex scaling does more harm than >good. There is a finite amount of energy delivered from the hammer >to the speaking length of the string. If that energy is dissipated >too quickly, being used up in exciting the vibration of the duplex >segments, it robs the speaking length of the energy required for a >desired longer sustain-time. At risk of raising the ire and >ridicule of the disciples of this logic, I must disagree. I must say I was amazed to find duplex scaling on this ancient Brinsmead concert grand -- which I forgot to mention also has a cast-in front bridge (capo) throughout. And Steinway copiers like Yahaha and Rachals were quite quick to adopt duplex scaling. I wasn't aware of this "modern" thinking -- my impression was that in recent years almost all previously "plain" makers, such as Bechstein, had introduced duplex scaling. Are you saying there is now a movement away from it? >...For this reason, I have to agree, in part, with the claims of the >Steinway patent that duplex scaling bolsters the harmonic structure >of the speaking length, and not only enriches the sound, but >contributes to a greater sustain, by producing a more efficient >system of recapturing already spent energy from the soundboard. >Those who would disagree with this would question if I have object >measures from testing to verify this. The answer is that I do not. >All I can offer is subjective observation that the tone is >noticeably weakened when duplex segments are muted out. It would be good to have scientific measurements but there is certainly a special and very desirable richness of tone associated with the Steinway and other well-made pianos with duplex scaling. >...For the desired effect, it is, of course, critical that the >duplex segments match the frequencies of the harmonic partials of >the speaking lengths. It is not good enough to rely on measurements >of lengths. One must tune the duplex segment, moving the duplexer >in or out to match the musical interval defined by the mathematical >relationship. With a continuous duplexer, the best that can be done >is to tune the first and last duplex segments of each continuous >duplexer. If the design of the duplexer is accurate, the >intervening notes should be in tune with their respective speaking >lengths, as well. I attach a couple of pictures of the Brinsmead showing the front bridge and the duplex arrangement. Though the piano is in fine condition, the hammers were re-covered about 15 years ago and I shan't be able to judge the tone properly until I have installed some good new hammer-heads. JD -------------- next part -------------- A non-text attachment was scrubbed... Name: brinsmead_02.jpg Type: application/octet-stream Size: 79990 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20110310/4ceb1edf/attachment-0002.obj> -------------- next part -------------- A non-text attachment was scrubbed... Name: brinsmead_01.jpg Type: application/octet-stream Size: 97523 bytes Desc: not available URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20110310/4ceb1edf/attachment-0003.obj>
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