---------------------- multipart/alternative attachment Sorry Ron, I was in Paris for some time and could not properly react. I think your cut off bar ideas are very interesting and of course I=20 would love to hear the differences between this and that instrument. Someday I hope to visit you and be able to listen to your instruments. btw..beautiful picture of the rims. How do you do that? (I am not a=20 real computer guy as you understand) Freindly greetings, Andr=E9 On vrijdag, apr 25, 2003, at 22:43 Europe/Amsterdam, Ron Overs wrote: > At 11:40 AM +0200 26/4/03, antares@euronet.nl wrote: > > I have been in this business for some time and I have never - really -=20= > understood the workings of the cut off bar. > > > Ideally, a piano should (all other things being equal) produce a=20 > superior tone if the long bridge is positioned at the center of the=20 > sound board. Of course, it is impossible to arrange for the bridge to=20= > be located perfectly thus, but an appropriately designed cut-off will=20= > help it follow this idealised situation more faithfully. > > While it is possible to produce an instrument with a most satisfactory=20= > tone, which nonetheless does not conform to this so-called 'ideal' of=20= > piano making, such an instrument may still have sounded a little=20 > cleaner and more controlled if it had a cut-off, allowing the long=20 > bridge to be more favorably positioned. > > Take a look at the following jpeg outline of a concert grand which I=20= > am designing at present. > <image.tiff> > For those who's email programme can't display the above image, I've=20 > uploaded it to; > http://overspianos.com.au/newslt.dec.02.jpg > (the image will be available for a couple of days. Please view it with=20= > your web browser). BTW, for those who were posting about log-style=20 > scales, the above long bridge conforms to a log-style design. > > Just digressing for a moment - that grand piano that you mentioned=20 > recently Bob I (when I was deeply immersed in sound-board-rib land) is=20= > crying out for a log-style scale down to D30, then a tenor with=20 > covered bichords from C#29 down to F21 (a silly place to cross in a=20 > 185 cm piano), with the complete removal of that suspended bass=20 > bridge. If the front duplexes are anything like the Hamburg=20 > alternative they will be screamingly noisy - definitely a de-tune=20 > required here - this means you get to play with your angle grinder.=20 > I've had local enquiries for rebuilding of this model which I've=20 > turned down on account of the unbelievable number of design problems=20= > which the instrument presents - its just too hard to make a buck with=20= > all the changes that are required. I've rebuilt three of them, and now=20= > would prefer to 'run for cover'. I can't understand how these builders=20= > persist with that model and continue to take themselves seriously.=20 > Nevertherless, it is possible to make it into something, as long as=20 > your prepared to ditch practically everything OEM. > > (and now its back to the subject at hand, which doesn't have a lot to=20= > do with hammers or rebuilding as such) > The RH piano image illustrates a case fitted with a typical small=20 > angled cut-off, which achieves little more than to provide a=20 > talking-point for the salesman's further boredom of the punters. The=20= > LH image shows just how an effective cut-off design can disable the=20 > unwanted distortion-promoting bass corner of the sound board. Corners=20= > make very poor shapes from an acoustical perspective. The curved=20 > cut-off will do much to eliminate the unwanted bass corner and to=20 > allow for the otherwise overly-long ribs, which span the board to the=20= > bass corner, to be shortened. Big sound boards do not necessarily=20 > produce big tone. The piano with the biggest sound board on the planet=20= > has a serious dynamic problem which is well known to students of piano=20= > design. > > Our future production pianos will not only have a curved laminated=20 > cut-off, but the bass corner area behind the cut-off will be filled=20 > with a structural plywood fill-in, which will be veneered with the=20 > same veneer as the inner surface of the outer rim. I can't see the=20 > sense in wasting valuable belly wood, for the sole purpose of blocking=20= > an unwanted hole. Much better to use 19 mm ply in its place, which=20 > will further enhance the lateral rigidity of the cut-off system. The=20= > saving in belly wood can be considerable in the case of a concert=20 > piano such as the one illustrated above. Also notice that the sound=20 > board with the real cut-off resembles a 'bent tear-drop' shape. This=20= > board will conform to that other ideal of a reducing sound board area=20= > from the bass to the high treble. > > =A0What I do remember however is the older Uebel & Lechleiter uprights=20= > without cut off bar, that sounded impressively nice, with the emphasis=20= > on mellowness and lower partial characteristics. > > > The old Ubels were indeed a fine sounding instrument, and proof that=20= > it is possible to build a nice sounding piano that is a bit 'rough at=20= > the edges'. They even had the good sense to place the break at=20 > D30/D#31, which was reasonably forward thinking for 1900. Some of the=20= > contemporary commercial manufacturers might well benefit from looking=20= > over a Ubel and pondering over these musically satisfying but=20 > economical creations. You never know, the production of a pleasant=20 > sounding cheaper instrument might even prove to be a new talking point=20= > on the sales floor, or am I being a bit old fashioned? > > Ron O. > > Now Andr=E9, I've had enough of this - thanks anyhow! Its 2.40 am here=20= > in Sydney, so I'm going to get horizontal for a while. > > -- > > _______________________ > > OVERS PIANOS - SYDNEY > Grand Piano Manufacturers > > Web: http://overspianos.com.au > mailto:info@overspianos.com.au > _______________________ > A. Oorebeek, The Netherlands see my website at : www.concertpianoservice.nl ---------------------- multipart/alternative attachment A non-text attachment was scrubbed... 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