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 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 ? 2) Should felt wraps be threaded through un-tuned bridge-to-hitchpin strings on pianos without duplex wedges ? 3) Should Aliquot strings be removed from Bluthners ? 4) What desirable partials and/or un-desirable harmonics are excited into these Duplexed areas. 5) How does a Duplexed string effect the practicalities of Tuning the Piano itself ? 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, but rather there is a ridge in the iron frame, a bit forward of the hitch pins, which is covered with a brass capping that is pretty well straight except for following the general curve of the bridge (i.e. it is not "notched" as is the bridge). The idea is the same (i.e. unstruck part of the string nearest to the bridge is undamped), but as the brass capping (defining the lengths of the duplexes) is securely located on the frame then it is definitely not adjustable by the tuner. Also, if we think about trichords, and if we assume that the centre string has its duplex tuned correctly in this system, we see immediately that the RH duplex for each note must be sharp and the LH duplex for each note must be flat! I suspect they found it didn't really matter much... 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
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