Yes , Heintzman did this on several models, including their concert grands. I was told that the theory was that the out of tune partials kept the energy going to make the notes sustain longer. Fortunately, partial tones grow weaker on the ascending notes, for if they were more audible tuning them would be even more miserable than are. I am certainly no acoustician, but common sense tells me that if sustain was increased by this means, then this would also apply to out of tune unisons.. If anything , the opposite may be true. If the condensations and rarefactions in two frequencies are nor the same, there must be a tendancy to be out of phase. At its extreme, the frequency might even be cancelled. For instance, the carrier frequency in an FM radio signal is 19KHertz, which would be audible to young ears, so FM radios generate the same frequency in opposite phase, resulting in canceling both. Try holding a vibrating tuning fork vertically close to an ear and rotating it on its axis slowly. There are four almost dead spots, caused again by being out of phase. and we are all aware of the weak sound if hammers are not properly fitted to the strings, also partly caused by the unison strings not moving simultaneously. Overall I generally found that the bridge design seemed to make little difference.Theoretically it should, as the differing string lengths violate the principle that all three strings have the same ratio of the stiking point to the string length. More serious is how most pianomakers ignore this priciple in the bass bichords. and poorly design the bass bridge. A well desgned bass bridge would have identical strings on a bichord, including pairing the hitchpins so that the backstring lengths and downbearing are similar. To do so would not increase cost, and one can only attribute the failure to do so to indifference or ignorance. I applaud makers like Bluthner, Ron Overs and I believe, Kawai who do this correctly. Dave Roberts in The Calculating Technician states that the strings of the bichord can differ in length by 3/8" without affecting tone, which is true, but the higher partials in the bass are very audible and will beat very rapidly. Thus, the tuning is affected, and so many pianos do not have clean sounding bass unisons. I think this arises from designers who are not tuners, so are not aware. Ted Sambell ________________________________ From: Don <pianotuna at accesscomm.ca> To: caut at ptg.org Sent: Tue, November 16, 2010 5:07:57 PM Subject: Re: [CAUT] Baldwin D bridge Hi all, Heintzman made a model "K" grand with this feature on the treble bridge. At 01:49 PM 11/16/2010 -0600, you wrote: >On 11/16/2010 1:35 PM, McCoy, Alan wrote: >> Has anyone seen this before? These pics (not great quality, but what can >> you expect from a phone, ;-)) are of a Baldwin D #141772. The top bridge >> section is notched normally, with the notch parallel to the capo. The >> mid treble bridge section is notched such that the bridge pins are in >> line with the bridge and at an angle to the capo. Then the notching >> returns to normal in the tenor section. What were they trying to achieve? > > >Hi Alan, >Yes, or something similar, and in pianos besides Baldwin. The idea was, >I think, to add some "sparkle" to a typically not terribly responsive >area of the soundboard by putting three different speaking lengths in >the unisons so they can't be tuned dead clean. I guess the tuned >duplexes weren't enough to save them. > >Ron N Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. Non calor sed umor est qui nobis incommodat mailto:pianotuna at yahoo.com http://www.donrose.ca/ 3004 Grant Rd. REGINA, SK, S4S 5G7 306-539-0716 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/caut.php/attachments/20101117/e9f7af2f/attachment.htm>
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