even tone?

[A440A@AOL.COM]

Stephen writes:
>The curious thing is that similarity of spectra is not a characteristic
>of 18th and 19th C pianos, and, in fact, composers frequently took advantage
>of tonal differences between registers, both conciously, for instance when
>passages are repeated at the octave (e.g. Pathetique, 2nd mvt.) 

Greetings, 
   Astute post there,  I like it when people start talking about sunrises in 
music.  I would like to delve deeper into the use of octave transpositions 
for tonal shaping.  
   In the Waldstein,(Op.53) we see a theme introduced in Emaj in measure 35,  
(for the really warped among us, this is the "Johnny Carson Show" theme at a 
different tempo!(:)}})  In virtually any of the tunings of the day, this is 
going to be a very contrasting key to the opening tonality of this piece.   
This passage is then played an octave lower in measure 39.  
    On the piano of 1800, I understand that this would cause a profound 
change in the spectra, since the registers would be so different, but was 
that the major reason? What I notice on the modern grand, ( In something like 
a Kirnberger)  the dropping an octave results in halving the tempering, with 
the "expression" also subdued.  This produces a much more relaxed feel to the 
theme's (originally brilliant) restatement after 4 bars.  
    My question, for Stephen is , is the effect of tempering less influential 
in this situation than the difference of voice to be found in the registers?. 
(Ya see, I have these pet theories that I MUST go out and find proof for and 
I certainly need to be careful not to let the facts get in the way.....(:)}}
Regards, 
Ed Foote