>I have been seeking a technical and practical clarification about the >DUPLEX question raised briefly on Piano-Tech last week. > >Quite obviously the effect of Duplex on the note diminishes as the >proportion of speaking length to tuned string length becomes smaller >and the stiffness, MOE, of the strings themselves increases. Yet, I >have observed duplex wedges going well past points where I would have >considered any inducement to sympathetic resonance or harmonics would >have been identified let alone capable of being tuned! The apparent stiffness of the string changes, but the MOE is constant for the material, regardless of length of diameter. While some duplexes possibly are too short to add much to the sound, and, in fact, are more probably constraining soundboard movement, they do serve to establish a string termination height, and down bearing at the bridge.. > >The whole question of sympathetic resonance in strings between >hitch-pin and bridge and the value of Aliquot strings in Bluthner etc. >seems to be confused by inconsistency between manufacturers and Piano >people generally. > >1) What do you believe are the merits, if any, in duplex ? *More sound. >2) Should felt wraps be threaded through un-tuned bridge-to-hitchpin >strings on pianos without duplex wedges ? *Only if they are noisy enough to detract from the desired sound, or interfere with the tuning (S&S model D, for one). >3) Should Aliquot strings be removed from Bluthners ? *No opinion, I haven't played with one. >4) What desirable partials and/or un-desirable harmonics are excited >into these Duplexed areas. *I don't really know. The purpose of the duplex is to make noise. It isn't necessarily 'tuned' to anything specific, and there isn't necessarily any correlation between pitch of any given note and the pitch of it's corresponding duplex. For any note struck in the piano, some duplex segment, somewhere in the scale, will respond. Serendipity sometimes supersedes intent. >5) How does a Duplexed string effect the practicalities of Tuning the >Piano itself ? *It adds more garbage to work around. If you mute off the duplexes when tuning, you notice how clear and clean the piano sounds during the process, and how shallow and lifeless the result is. When you uncover the duplex, the piano comes back to life. I don't normally mute duplexes when tuning, but I've run into a few instances where it was necessary, particularly in the front duplex. >6) add more questions ..... ? > >The following observations have been made by a UK corespondent and I >will be interested in comments from Technicians on Piano-Tech. Neither >my Bechstein C or Ehrbar have tunable duplex and there seems to be a >complete lack of definitive instructions for tuning the wedges on >Yamaha and Steinway etc. > >-----Original Message----- >From: Dr. Clive Woods >Sent: Saturday, June 13, 1998 5:11 AM >To: Alan W Deverell >Subject: P.S. Re: Tuning Duplex > >It occurs to me that in some makes (Bechstein? Bosendorfer? Seiler? >Grotrain?) there are not wedges for the Duplex scale, --snip-- >Ever seen a piano with _front_ duplexes? Same idea, but it is the bit >on the keyboard side of the plate bridge that is duplexed. An old >Steinway B in Sheffield Cathedral is like this. It sounds terrific, >but I'm not sure how much is due to the duplexes! Theoretically this >should have much less effect, of course, so it was very quickly >dropped by Steinway. > >Clive *The reason there are no instructions for tuning these duplexes is pretty straight foreword. There isn't much point. The designer either had a devilishly clever and obscure reason for placing the aliquots where he did, or it was done entirely arbitrarily. The resulting sound, in either case, is going to be very similar. Ron
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