<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi Ron, <p>Thanks for the reply. I should have remembered that you have been doing work in this area as well. I have the same question as Fred. <p>Don <br>  <blockquote TYPE=CITE> <pre>Subject:             Re: Capo bar revisited       Date:             Thu, 29 Jan 2004 08:29:45 +1100      From:             Overs Pianos <sec@overspianos.com.au>         To:             College and University Technicians <caut@ptg.org>  References:             1   Hi Lance,   Thanks for the update and sorry to hear it did not work out to your satisfaction. It is clear from previous discussions   that there is no guarantee all the cures mentioned will work. Regarding the capo, sometimes we get lucky, sometimes   not. I have been leaning towards the school of thought that suggests good tone can be achieved without the front   duplex section ringing at a higher harmonic of the speaking length. Yes, that would mean major rescaling for Steinway,   etc. (Not likely to happen :-) It seems to me that a lot of problems could be solved by this design. Pardon me if I'm   incorrect, I believe Del has proposed this on the lists and in the Journal.   Don Don, Lance and all, If you measure the front duplex lengths relative to the speaking lengths, of Steinway and Yamaha grand pianos in particular, you will find that both have attempted to set the front duplex lengths to a harmonic length of the speaking length, ie.  a 1/2, 1/3, 1/4, 1/5 . . . 1/10, 1/11  etc.  This practice is a sure-fire way to allow for the production of lots of string noise. Furthermore, most manufacturers do not harden their capo and duplex bars to prevent the strings from deforming the bar profiles - if indeed they bother to shape them properly in the first instance. Yamaha harden their capo bars but leave the front duplex bars soft (we know this because we have reshaped several late Yamaha piano capo bars and front duplex bar sets, and their capos are quite hard when removing metal with the die grinder tungsten burrs). Both capo and front duplex bars are capable of producing noise. Steinway Hamburg claim to be hardening their capo bars with a laser treatment, but an inspection of any modern Hamburg piano will reveal that their bars are being deformed very nicely by the piano wire, regardless of their claimed hardening process. When we harden the bars of our pianos there is no deformation of the bar from the string. Indeed, the strings can be aligned with ease throughout the service life of the piano, since they don't cut grooves into the bars as they will when the bars are too soft. I know that Mr McMorrow is not in favour of hardening capo bars, and I should like to discuss this matter with him at some time should the opportunity arise. But we have found that when hardening is combined with careful shaping of the bearing surfaces and a deliberate detuning and shortening of the string segments, the result is highly satisfactory. One disadvantage of hardened bars is that the tuning pins fields must be aligned properly to the speaking lengths segments, to allow the strings to run straight from the tuning pin through the various string segments. If the string segments are not in line there will be a tendency for the strings to migrate along the duplex and capo bars as the piano is tuned. Thankfully if the bars are hardened the alignment process is simple, but its annoying if the strings continue to wander throughout the service life of the instrument. I have proven to my satisfaction that tuning the front duplexs to their respective speaking lengths is a recipe for disaster. I have conducted experiments whereby a moveable front duplex is set precisely to a harmonic of the speaking length and it definitely causes those levels of string noise which many of us have come to detest. After moving the front duplex to detune it from the speaking length the noise disappeared. However, if the chosen duplex length is around 40 mm it will be noisy no mater where it is positioned. So the typical grand piano front duplex lengths chosen by many manufactures is a contributing factor to the production of string noise. Notice that you rarely hear string noise from upright pianos, yet there is often a short string segment between the V bar and the pressure bar which is undamped. The short, typically around 20 mm, string segment of the upright piano tends not to produce string noise because it is too short to be active. In the grand piano, with front duplex lengths which are often up to 40 mm or more in length, noise is almost guaranteed. Our approach to this problem in recent years has been to remove the original front duplex bars with an angle grinder, and manufacture a new set of bars with a small radius rounded apex which is hardened to prevent deformation. After measuring the speaking lengths of the string sections concerned we enter the information onto a spreadsheet which is designed for the purpose, choosing the shortest possible de-tuned front duplex lengths for each note. We then move to the plate which has been previously levelled (if necessary, with motor-vehicle body filler) to accept the new set of duplex bars, to determine the height of the duplex bars in their new positions to establish the correct height for the bars (which will be tapered in height along the length of each bar) to allow all strings to run to the capo at the desired string angle. We set the string approach angle to no greater than 15 degrees or less than 12. A higher approach angle will tend to produce less string noise, but any angle over 15 is likely to allow the small radius hardened capo and duplex bars to act like string cutters, and will shorten the string service life. We have found 15 degrees to be the practical maximum angle which will allow for a satisfactory service life with the bar radii that we use. Of course you could use a larger bar radius with a higher string approach angle and that would be fine, but with the small radius bars we use 15 degrees is the maximum approach angle. For those of you who haven't heard a piano with a deliberately de-tuned hardened small radius capo and front duplex system, please link to the mp3 sound samples of our piano no. 3 online at; <A HREF="http://overspianos.com.au/samp.html">http://overspianos.com.au/samp.html</A> The treble tonal clarity of this piano is not a fluke. All our pianos (including the rebuilt instruments) have the same characteristics. It is satisfying to have found that it is possible to put the problem of string noise behind us, provided that we are prepared to step beyond slavishly following that standard which was set over a 100 years ago. Ron O. --  OVERS PIANOS - SYDNEY    Grand Piano Manufacturers _______________________ Web <A HREF="http://overspianos.com.au">http://overspianos.com.au</A> <A HREF="mailto:info@overspianos.com.au">mailto:info@overspianos.com.au</A> _______________________</pre> </blockquote> </html>