<HTML> <HEAD> <TITLE>Let-off button felt compression vs let-off timing </TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF"> ---------- From: "Dan & Martha Reed" <pianoman@airmail.net> To: carpthos@televiso.com Subject: Let-off Date: Fri, Feb 25, 2000, 10:52 PM <BLOCKQUOTE>Tom:     I really like your awareness of this problem. I hav= e wondered about this, but never thought to single out the reasons why.      I would be willing to bet the bundle on co= mpression of the knuckle, as the #1 reason that let-off moves away from = the wire, faster than compression of the let-off button felt tries to move e= scapment  closer. The weight of the hammer is constantly compressing th= e knuckle, as it sits on the jack. Try this test. Place a piece of thin felt= , like key bushing cloth)  or even something as thin as a business card= between the knuckles and the jack tops. Now compare the "new" hei= ght, in relation to the hammer height adjacent to these. Because the hammer = is way out on the end of the lever, a little movement of the knuckle (compre= ssion) is magnified greatly. (I would guess about a 10 to 1 relation here.)<= BR>    The #2 reason would be that the hammer felt has wo= rn away. Before dismissing this 2nd. reason, compare a new hammer with a wor= n one on these old pianos.     Any other felt compression would not change the let= -off position. Compression of the back rail cloth, balance rail punching, ca= pstan contact felt, hammer rest felt or even movement of the key bed, won't = change let-off timing. These other changes will reduce how far the whippen (= i.e. jack) travels, and these changes can be so limiting that the jack won't= complete its let-off function.      The blow distance is usually 2" plus in = these actions, with let-off happening 1/4 plus from the wire. The jack is ma= king it to the let-off button, but there is usually not enough remaining jac= k travel to get the desired after-touch. Of course, the real problem here is= : no control of pianissimo:and poor "average" response.)     The real clairifying test, to check out what these = other compressed felts do, is to crank the capstan up or down, and measure i= f this changes where let-off occures.      I am teaching a class at the National convent= ion this summer very much relating to let-off timing. It is called "Performance Regulation / Voicing in Everyday Service.&qu= ot; If you can't make it, and are interested more in this subject, please ke= ep in touch. Dan Reed </BLOCKQUOTE> </BODY> </HTML>