<HTML> <HEAD> <TITLE>Re: Research for fine tuning unisons</TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF"> > Concerning changing (lowering) the pitch of a solid wire by rubbing th= e > wire with a brass dowell, > Dan Jackson wrote... >  >snip> >>Have you thought about trying to measure the pitch or the tension<B= R> >>change (if any) in the duplex area and between the tuning pins and = capo >>or agraffes? It seems pretty important in order to establish a comp= lete >>idea of what is happening. Checking the duplex area aurally would b= e >>possible but maybe not accurate enough.? >  >Dan J in Wmbg VA > > Dan Jackson, >      Thanks for your input. I will try some a= ural tests in these areas you > mentioned.      Here are the  findings of my  resea= rch so far... > Today, I played with lowering the pitch of a solid wire by the 'heatin= g' > method... that is, rubbing the wire with 6 to 8 ten inch strokes, usin= g a > brass dowell with a rounded groove cut into the tapered end. I am stil= l > amayzed at how much of a pitch change that 'simply' rubbing the wire c= auses. I am > applying as little downward pressure as possible, so as not to pull th= e > wire through its termination points. I am also surprised at how the pi= tch > climbs right back up, when the unison is played. It takes about 30 sec= . for > the pitch to come back up, and of course it can be heard coming back t= o 'about' beatless, as one plays the unison, about 10 times. >     The theory I am trying to 'prove', with the ru= bbing method, is that the > wire will not come up to 100% of it starting pitch, after rubbi= ng. During its fall, can 100% of the 'loss' be recovered?  There is als= o a > possibality, that some wire which has some slight uneveness in the len= th being > rubbed, and will 'strighten out, and therefore lengthen, and drop in p= itch.  I > say this, because one can feel the bumps in some wire, when using this= tool. >     My test for pitch involves using Maj. thirds (= which produce a fast beat speed) and maj. 6ths., and comparing the beat spee= ds of two solid > wires, and then lowering the 'high' wire with the rubbing method. Ther= e is the > temptation to force the wire to pull through its termination points, t= o cause > a greater change, because the net effect of rubbing seems to be minima= l. (The more > aggresive method, that of pulling the wire through its termination poi= nts, > is useful, and more commonly used, but I am limiting this study to wha= t our > fellow technician Graeme Harvey correctly idenitfied (I beleive) as he= at induced change, by rubbing, > causing the wire to lengthen slightly( lengthening is my guess).) But,= minimal change is O.K. for some > unisons, oui? i.e., this method might work well when very small change= s are > useful for nailing a unison. I am looking forward to modifying the str= oke > amount/length of stroke etc., to see if there is a reasonable, predict= able > method that can be used. For now, I have limited the stroke to about o= ne > half the length of the speaking length of the wire, and have been test= ing in the two octaves starting from about middle c - up.    >     The piano I am testing on, is one that gets tu= ned once a week, (about a > 30 year old 9' Baldwin) so I have the luxury of spending time trying t= o > clean up unisons. Dan Reed Dallas Chapter </BODY> </HTML>