Dan Franklin wrote; >3. BuzZing duplexes. If by testing it can be ascertained that the duplex >portion of the string is causing a buzz, the simplest remedy is of course to >mute it. Muting the front duplex will 'kill' the note. Yes I know that some factory tech's mute noisy duplexes for the international piano competition pianos also (I've seen it many times) but its still a poor solution. Jim Coleman posted an excellent solution to this problem last year, when he suggested placing a drop of glue onto the centre of the offending duplex length. This increases the effective mass of the duplex wire, lowering its pitch to detune it from the speaking length. I have used this technique many times since to good effect. Thank you for the tip Jim. Some months ago when tuning a Steinway O, note G71 had a screaming duplex on the left unison only (the duplex lengths varied for the three unisons since the duplex bar on this Steinway is continuous, and not individual blocks for each note). Obviously, (to me after doing experiments on tuned duplex problems in August 2000) the problem appeared to be that the left hand duplex length was nearly in tune, causing the string noise. After placing a drop of glue on the offending duplex, the string noise totally disappeared, and it remained absent at the next tuning also. There you go Dan, after doing the experiments firstly in the workshop, then finding a problem in the field, the field trials supported the findings at the workshop. You mentioned in a post a couple of days ago that the 'naysayers' hadn't done any experiments to support their theory on the need for duplexes to be detuned. I disagree with you. I have done experiments in this area, and Jim's solution adds further weight to my own findings. >However, I have never heard or seen any scientific data or >experiment that proves that tuning the duplex causes the buzz. You are probably not looking hard enough Dan. Information on this very matter was posted to this list during the past week. You must have missed it. If you would like to see a copy, email me at; mailto:ron@overspianos.com.au and I'll send you a copy of my post to the list. >I highly doubt >it. However it may be possible that the bearing of a duplex scale does not >conform to mfg specs and altho the duplex may be in tune, the bearing may be >insufficient producing a buzz. Check out Ed Foote's post of a couple of days ago. He knows where it's at. >But this is conjecture on my part. It certainly does seem to be. Was it you Dan who mentioned on this list a couple of days ago that you thought it was inappropriate for technicians put forward views which were after all only opinions, without having done the experimental work to support their views? Yes I thought it was you. Sincerely, Ron Overs -- ______________________________ Website: http://www.overspianos.com.au Email: mailto:ron@overspianos.com.au ______________________________
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