<html> Hi Ed,            I'm Not sure if I have any answers, just lots of questions around this topic. Your tip of rock hard hammers is key to many questions, I'm in the midst of some research with regards to the PAZ section of RCT to try and find some simple applications re voicing, and stretch.   Since ET's are partial dependent, and the values recorded are both dwell time and inharmonicity dependent, a whole mess of anomalies creep into the discussion.   For instance, I have now re hammered and shanked 4 model C3 grands, on average the stretch factor drops from 40 to 30 cents after voicing from factory to acceptable ideal.( whatever that may mean.Classical players!)   The harder the hammer in the centre to treble the stronger the fundamental and the weaker the harmonic series. Hammer blow weight has to be very exact to obtain reproducible results. If fact calibration readings seem to require a ppp blow to obtain a sensible tuning curve. It would be interesting if some SAT users could feed back some info, with regards to sampling and dynamic range.   After working with RCT and PAZ for about 6 months I have come to the conclusion the a well voiced piano for classical use needs to have the partials decay exponentially in both amplitude and sustain.  In the Bass section I tend to look for a parabolic curve of partials, with as smooth a transition as possible.   The above is a very short over generalization of some early results, to help stimulate some feed back.  It leads us into several areas of potential discovery. 1. Dwell time and the harmonic series.  Cause and effect. Hammer elasticity and jack lost motion or clearance. I have measured differences in both. 2. String coupling re unisons, stretch factors seem to change, one string, or a near perfectly tuned full unison. I used a drop weight for consistency of blow after three repitions to break static friction. 3. Tapeing off rear and forward duplexing seems to effect results, test that I have done thus far are not scientifically valid, but I'm starting to get a gut feel. 4. Anomalies that creep into the system when measuring on the upward or downward slope of the modulus curve (60% point)   Newton's observations are valid for two reasons. 1. With very bright hammers the test weight of the blow is critical. 2. With the higher humidity, the hammer becomes a little more elastic, therefore a little better harmonic development.( in a classical sense)    Our hearing plays a lot of tricks on us, for instance tuning in the treble to the second partial, and it is barely there, do we revert to the fundamental sub consciously?  and correct for the best sounding octave?   As I said no answers just questions Regards roger At 08:56 PM 13/01/99 -0500, you wrote: >Newton writes: >< >change with the humidity changes from 15% to 85% on the same piano in >the same room.  At a university tuners tune the same piano time after >time after time and some things become obvious in that setting that do >not otherwise.>> > >      Hmm. I dunno.  The first example that comes to mind here is a 1910 9' >Chickering with an Al Sanderson scale and rock hard hammers.  This piano is >used in a recording studio and is known as one of the really "hot" country >pianos for recording work here in Nashville.  >     I tune this piano about 100-150 times a year, and was tuning the piano >aurally from about 1978 until my SAT arrived in 1992, at which time, I >recorded my working tuning and began using the machine.  >   The producers and players have never noticed a difference through all >ranges of humidity over this time, and neither have I.  This may be because >there are none,  or it may (more likely) be that I didn't know where to look >to hear it (:/}}} >    What changes would show themselves aurally ? Does A's inharmonicity go up >or down with a rise in humidity? >(Thinking, What have I been missing...................?.) >Ed Foote > <div>Roger Jolly</div> <div>Baldwin Yamaha Piano Centre</div> <div>Saskatoon and Regina</div> <div>Saskatchewan, Canada.</div> <div>306-665-0213</div> Fax 652-0505 </html>