I have seen a demonstration of coupling strings with a staple-like device in order to tame excessive false beating. It was interesting how far out-of-tune with each other they could be before you would hear a beat. The coupling done in this fashion weakens the higher partials and so in the plain wires is usually utilized only on two strings of a unison. In the bass weakening the the higher partials would be a blessing on some the of cheap Asian "pianos" I've tuned. I do like the Sauter treble, I have an Omega here at the store and it also has titanium pins etc. Strong, well balanced trebles, do seem to be the hallmark of all the Sauters that have passed through this store. Andrew Anderson On Jun 10, 2009, at 4:57 PM, Ed Sutton wrote: > If you can hear the string, it's fair to assume the soundboard is > moving at frequencies similar to some of those in the string, > therefore it's reasonable to assume that the bridge is also moving. > Thus it is also likely that when frequencies are very close, > coupling will occur. The amplitude of the wave in the string will > play a role as well. Perhaps when it becomes too small to move the > bridge, the strings de-couple, at least at that particular partial. > > This may not involve all the partials of the unison at all times. > For example, in the higher octaves the first partial may become > inaudible almost immediately. The Sauter concert grand with titanium > armor in the top octaves is remarkable for the clarity and sustain > of the first partials in octaves 6 and 7. > > Ed S. > > > ----- Original Message ----- From: "Richard Brekne" <ricb at pianostemmer.no > > > To: <caut at ptg.org> > Sent: Wednesday, June 10, 2009 6:01 PM > Subject: Re: [CAUT] String Coupling / SB and Bridge stiffness > > >> Hi... no bites on this so I thought I might try phrasing it a >> different way and see if I could get any feedback. >> If the string terminations were infinitely stiff, then there would >> be no mechanism for string coupling .... yes ? You could in theory >> have a piano unison, excite the strings in the usual way with the >> hammer.... but the infinite stiff terminations would not allow for >> any coupling, there by the strings would each vibrate completely >> independent of one another. Ok.... so add a set of non infinitely >> stiff bridge pins and leave everything else about the terminations >> infinitely stiff. You still have the same situation, tho the bridge >> pins become some form or another of an extension of the string. >> Perhaps this scenario would open for false beats on individual >> strings at best, but there is still no mechanism for the three >> strings to couple given the infinite resistance to vibration by the >> bridge itself. So no pitch drop due to coupling is possible as no >> coupling is possible to begin with. Yes ??... So at some point the >> bridge becomes non-stiff enough to allow for this coupling. And >> the more non-stiff the bridges becomes... the greater the ability >> for the strings to couple, hence the greater their influence on >> each other... and hence the more evident (greater degree ?) of >> pitch drop.... Or what ? >> >> Cheers >> RicB >> >> Got to thinking abit about string coupling and the mechanisms that >> are at work that account for the pitch drop and got to wondering if >> it is viable to think of the degree of pitch drop when 2 and 3 >> strings are coupled in on a unison as an indicator of SB/bridge >> stiffness at any given note. >> >> Or... is this another one of my rabbit holes ? >> >> Cheers >> RicB >> >
This PTG archive page provided courtesy of Moy Piano Service, LLC