Yo Horace, Again yes, and no. From the first day (well, maybe the second) I heard the term "bridge roll", I've maintained that it's a *symptom* of soundboard failure, not a *condition* of anything. On second thought, I wouldn't rule out the fallen arches theory just yet. I too have seen/heard pianos that sounded far better than my probably debatable diagnostic criteria can account for. I'm just flailing about for some very general parameters here. I'm sure there is a whole lot more going on than I can account for with a few simplistic "rocks in the ocean" shots. One starts, however, by picking up a few rocks. Susan's "thinner ribs" idea was more to negate the effect of centering a bridge on the rib by making the rib asymmetric - thicker on one side of the bridge, thinner on the other. Good thought, as I stated. My original post proposed ever more and thinner ribs and a thinning of the board toward the treble to attempt to more nearly match the natural harmonic frequency of the board with the note frequency at any given point on the bridge. "That's no ordinary rabbit!" P.S. - Cool it with this talk about soundboard compression ridges. If word gets out, everyone will want one. Goon 'un to you, Ron At 06:23 PM 12/8/97 -0800, you wrote: > >Ron, > >I agree in part and demur in part. > >Some time ago there was a very great deal >of what propeller-heads would call vaporware >about bridge rolling. This product of creation's >nether reaches was held responsible for everything >from tuning instability to fallen arches, err, crowns. > >While it is quite clear that this _is_ >a substantive problem in some pianos, >I've certainly seen some pretty decent >instruments with what would have been >considered unacceptable levels of "bridge >roll"...and not a few that have been >severly damaged by attempts to "repair" >same. > >Was it Susan who suggested perhaps thinnner >ribs? (Sorry, braindead) In any event, several >of the AA and BB M&Hs I've done over the >years had not only more ribs, but smaller >ones (crossectionally). These instruments >came out sounding (largely) like M&H >pianos used to, and had minimal amounts >of surgery required to re-establish good >bearing and termination. > >Oh, yes, most of them did not exhibit any of >the tone-enhancing ridging we've heard so >much about recently... > >Best. > >Horace > >P.S. - Come back and I will taunt you yet >another time! > >hg > > > >At 06:21 PM 12/8/97 -0600, you wrote: >>Interesting thought. Might change the frequency response on one side enough >>to not cancel the other and kill the tone. >> >>Observation: Even if this minimized or canceled the immediate tone problems >>in that area, there would still be the problem of torque with humidity >>changes. I think this is what drives the board flat at this point far faster >>than it flattens elsewhere. Sort of a "saddle" effect, with the killer >>octave at the low point of the curve. I think both the tone problems and >>early failure in this area are from the same problem. Tag! >> >>Ron >> >>At 11:11 AM 12/7/97 -0800, you wrote: >>>Curiosity aroused: >>> >>>The "killer octave" has equal lengths of rib fore and aft of the bridge, and >>>the tone has trouble there. Has anyone ever tried making the ribs the same >>>length fore and aft, but making them much lighter and more flexible on one >>>side than on the other? >>> >>>What fun ... reminds me of that great string seating thread. >>> >>>Susan >>>----------------------------------------------------------- >> >> >> Ron Nossaman >> >> >> >> >Horace Greeley > >Systems Analyst/Engineer >Controller's Office >Stanford University > >email: hgreeley@leland.stanford.edu >voice mail: 650.725.9062 >fax: 650.725.8014 > > Ron Nossaman
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