Unison Width

[A440A@AOL.COM]

Terry writes: 
>I too, have tuned 
quite a few "cheaper" or older uprights/grands, where it does indeed seem 
that the margin for tuning a unison beatless, is RAZOR thin. <<

 Greetings,  
     It seems that the most noticeable unisons are the ones that stick out.  
If you have an octave or so of near-perfection going, with limpid, glowing, 
resonant unisons,  and then come across a trichord that has a real riot 
happening in one or more of its strings, it is going to stand out.  If, on 
the other hand, every single one of those trichords is cursed with the false 
beats,  a good tuning requires that they all howl the same.  
     On request for a "honky tonk" sound, I once used a SAT to move one 
string on all trichords above G4 up by 2 cents,(using the SAT for this keeps 
a level of consistancy here so that intervals don't get too cloudy).  The 
piano didn't really sound out of tune when played, (it sounded like there was 
signal processing going on).  Everybody soon got used to it.  I did get one 
complaint about a dead note, and when I arrived, I found that the raised 
string  had slipped, BACK INTO TUNE!  The clear unison stood out.   
      A consistant out of tuneness stops being perceived as "out of tune".   
I would also submit that this applies to harmony as well as unison, as 
evidenced by so much acceptance of ET, which has everything "out of tune".  
(Anyone ever talk about temperament around here? (:)}))
      There are no absolutes, and the purest of pure unisons may not be the 
most desired state,(see Weinreich). With this in mind, perhaps  the cheaper, 
more tonally deficient pianos  require a wider margin to their unison width, 
as in, don't make ANY of them pure, but rather, compromise them all so that 
they sound the same.   
     Width also doesn't completely describe what three strings are doing.  
Width might be accurate for two strings, but the addition of the third means 
that another level of complexity is in the signal.  Whereas two strings 
describe a distance,(width), three describe a space.   The phase manipulation 
available to the tuner becomes  more extensive here, as moving one string can 
create several different relationships.  These differences create the sound 
of the unison, and there is room to shape them on a good, clean piano.  
Studio unisons, for me, occur most consistantly when I tune the outer strings 
to the SAT and let my ear settle the middle pitch down amongst the 
"envelope".  This produces a pretty consistant sound through the microphones, 
and consistancy is what sells.  (Oops, I digress,  I think we started on 
old/cheap pianos!)   
   Ah well,  unisons can be a very deep subject, on levels both techical and 
personal.  Unison between not only three vibrating wires but also among those 
of us fascinated by such arcane angels dancing.  Happy Thanksgiving to all. 
Regards, 
Ed Foote RPT 
Nashville, Tn.