<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE>Re: Counterbearing (& Kowmung report)</TITLE> <META content="text/html; charset=iso-8859-1" = http-equiv=Content-Type> <STYLE type=text/css>BLOCKQUOTE { PADDING-BOTTOM: 0px; PADDING-TOP: 0px } DL { PADDING-BOTTOM: 0px; PADDING-TOP: 0px } UL { PADDING-BOTTOM: 0px; PADDING-TOP: 0px } OL { PADDING-BOTTOM: 0px; PADDING-TOP: 0px } LI { PADDING-BOTTOM: 0px; PADDING-TOP: 0px } </STYLE> <META content="MSHTML 5.00.2919.6307" name=GENERATOR></HEAD> <BODY bgColor=#d8d0c8> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A href="mailto:sec@overspianos.com.au" = title=sec@overspianos.com.au>Ron Overs</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A href="mailto:davidlovepianos@earthlink.net" = title=davidlovepianos@earthlink.net>davidlovepianos@earthlink.net</A> = ; <A href="mailto:pianotech@ptg.org" = title=pianotech@ptg.org>Pianotech</A> </DIV> <DIV style="FONT: 10pt arial"><B>Cc:</B> <A href="mailto:tourism@oberon.nsw.gov.au" title=tourism@oberon.nsw.gov.au>tourism@oberon.nsw.gov.au</A> ; <A href="mailto:esi@lisp.com.au" title=esi@lisp.com.au>Hans = Guldberg</A> ; <A href="mailto:morganisation@ix.net.au" = title=morganisation@ix.net.au>Barbara Morgan</A> ; <A href="mailto:suspence@ozemail.com.au" title=suspence@ozemail.com.au>suspence@ozemail.com.au</A> ; <A href="mailto:john.a.spence@au.pwcglobal.com" title=john.a.spence@au.pwcglobal.com>John Spence</A> ; <A href="mailto:peterdickson@bigpond.com" = title=peterdickson@bigpond.com>Peter Dickson</A> ; <A href="mailto:robertsmith@ozemail.com.au" title=robertsmith@ozemail.com.au>Robert Smith</A> ; <A href="mailto:llobster@ozemail.com.au" title=llobster@ozemail.com.au>llobster@ozemail.com.au</A> ; <A href="mailto:santon@ozemail.com.au" title=santon@ozemail.com.au>santon@ozemail.com.au</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, March 30, 2003 = 4:00 PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Counterbearing = (& Kowmung report)</DIV> <DIV><BR></DIV> <DIV>Hi David and all,</DIV> <DIV><BR></DIV> <DIV>I've just returned from a weekend away at the Kowmung Music = Festival<FONT color=#0000ff> (held each year in the picturesque Blue Mountains = town of Oberon, 2 hours drive west of Sydney)</FONT>. Visiting artists the = Kutrowatz Duo (Eduard and Johannes) from Austria were again most impressive. = Similarly impressive performances were given by a number of Australian pianists = and instrumentalists over the two weekends of the festival. On Sunday 22 = the Sandy Evans quartet performed in the first jazz concert to be featured at a = Kowmung Festival. Her outstanding artistry on Saxaphones was complimented by = drummer Toby Hall, bassist Lloyd Swanton and pianist Allister Spence, with = guest artist Peter Jenkin on bass clarinet. For many Kowmung patrons, this performance would have been their first attendance at a jazz concert. = The standing ovation they gave the quartet would tend to suggest that jazz = will become mainstream, alongside classical, for future Kowmung = Festivals.</DIV> <DIV><BR></DIV> <DIV>For those who may be interested, the English language version of = the Kutrowatz Duo website can be found at;</DIV> <DIV><A = href="http://www.duokutrowatz.com/English/english.html">http://www.duok= utrowatz.com/English/english.html</A></DIV> <DIV><BR></DIV> <DIV>The Kutrowatz Duo performed on our piano no. 3 and a = Bösendorfer 225. The original plan was that they would use two of our pianos, but since we = are still building piano 4, we hired the Bösendorfer 225 form the ABC = Ultimo Center. While Eduard and Johannes are most proficient and sensitive = classical pianists, they seem equally capable of turning their hand to jazz = repertoire when required. Their two piano transcription performance of Dave = Brubeck's<I> Blue Rondo A La Turk</I> was most exhilarating. Although it was not = included in the programme, neither was the heavy rain on the tin roof of the = Middle Creek Cattle shed. In the true spirit of professionalism, they decided = treat the audience of 300 with a work which would cope with the poor signal = to noise ratio. The audience responded to the outstanding duo brothers with a = standing ovation.</DIV> <DIV><BR></DIV> <DIV>At 6:58 PM -0800 29/3/03, David Love wrote:</DIV> <DIV><BR></DIV> <BLOCKQUOTE cite type="cite"><FONT size=-1>I meant to ask one = other question.  My recollection is that the ideal angle leaving = the capo section up to the counterbearing bar is 17 degrees.  I'm = not sure why that number sticks in my head--I may have gotten it from a piece = that Ron Overs wrote, or I may be mistaken entirely.</FONT></BLOCKQUOTE> <DIV><BR></DIV> <DIV>I believe that, where possible, the counterbearing angle behind = the agraffe section should not exceed fifteen degrees or be much less than = 10. While it is possible to set the counterbearing behind the agraffes to = be higher than 15 degrees without risking wire breakage, it will tend to accelerate the deformation of the agraffe.</DIV> <DIV> </DIV></BLOCKQUOTE> <DIV><FONT size=2>This has not been my experience. (See my Journal = articles <EM>V-bars, Pressure Bars and Duplex Scales</EM>, June 1995 and = <EM>Front Duplex Stringing Scales</EM>, August 1995.)  There doesn't seem to be any perfect answer to this question. The string deflection angle is = a function of the string segment length between the V-bar and/or the = agraffe and the first counterbearing bar. If this string segment is very short--as = in the typical vertical piano design--the string deflection angle can be rather = shallow (5º or 10º may be adequate. If this string segment is = longer--say something of 35 or 40 mm--the string deflection angle is going to have to be some = greater. In this case a deflection angle of 20º or 25º will be = required.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV> This will lead to premature 'string noise'. Furthermore, = while it is desirable to have quite a short string segment between the agraffe = and the counterbearing bar/felt, the tendency of a great many manufacturers is = to overdo it. If the segment is made too short, it will tend to 'shut = down' the freedom of the speaking length. I ran some experiments back in 1995 = which proved this to my satisfaction. Now while I'm not prepared to publish = details of this on the Pianotech list, for those of you who are interested, = conduct your own experiment to draw your own conclusion. Just remember that = human flesh has high hysteresis loss characteristics<FONT color=#0000ff> = (quite a number of default 'experiments' are taking place elsewhere in the = world as we speak)</FONT>. So if you are tempted to hold a test piece of metal in = your hand, you will need to insure that you de-couple the hysteresis loss.</DIV></BLOCKQUOTE> <DIV><FONT size=2>This is always a balancing act. Short string = segments work just fine with rather shallow string deflection angles. This is the = arrangement typically found in vertical pianos and is one which works quite well. = Problems arise when the shallow deflection angle is coupled with longer front = string segments as is found in the Steinway (and clones) vertical designs. And = when steep deflection angles are used with short front duplex string segments.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <DIV><FONT size=-1>     What is the maximum = angle in the capo section that you can get without risking breaking = strings.</FONT></DIV> <DIV><BR></DIV> <DIV>I would not recommend over fifteen degrees in the capo sections.</DIV></BLOCKQUOTE> <DIV><FONT size=-1>It depends on the length of the front duplex string = segment. Typically, in a grand piano, this is going to be somewhere in the = vacinity of 25 to 35 mm and a string deflection angle of somewhere between 15º and = 20º will work quite nicely.</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>We have not found deflection angles up to about = 25º to be any problem when used with the extremely long front duplex string segments = sometimes found in oddly designed pianos.</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <BLOCKQUOTE style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: = 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px"> <BLOCKQUOTE cite type="cite"> <DIV><FONT size=-1>I would assume the materials would make a = difference too.  In the capo section where the strings bear against cast = iron, I would assume that they would tolerate less of an angle = than where the strings where redirected by softer brass agraffes.</FONT></DIV></BLOCKQUOTE> <DIV><BR></DIV> <DIV>I'm not so sure about this, but I have not conducted experiments = to prove it either way. However, once the piano wire has cut a significant = groove into a brass bar or agraffe<FONT color=#0000ff> (and it will)</FONT>, the = friction can be considerable, regardless of the base material softness.</DIV></BLOCKQUOTE> <DIV><FONT size=2>"Brass" agraffes are not always made of "brass." For = some time Steinway used a material called (if memory serves) <EM>Silnic</EM>. This = is a silicon bronze alloy also containing a small amount of nickel. The = material is actually somewhat harder than the typical gray iron used in piano = plates. It is an excellent material and the agraffes would have been quite good if the = machining had been just a bit better.</FONT></DIV> <DIV> </DIV> <DIV><FONT size=2>Del</FONT></DIV></BODY></HTML>