Capo termination, was Re: Why NOT to polish bass strings.......

[Frank Emerson]

> Sounds like that might be Baldwin.

Bingo!

> I'm not so sure the hard 
> termination is at fault, but rather the long front duplex the 
> termination piece defines.

I did a study of this, which confirmed what my ear was hearing.  I used a
spectrum analyzer to create an FFT (Fast Fourier Transform), graphing the
partials for each note in the capo range.  Unlike other pianos with
traditional v-bars, the notes with termination pieces all had a prominent
non-harmonic partial, about the frequency of C8, present in every note.  I
have to believe that the hardness of the termination is a contributing
factor to this condition.  I have seem other pianos, with traditional v-bar
design and similar front duplex lengths, which do not exhibit this
phenomenon.  

Even in some vertical pianos, with two separate pressure bars for the tenor
and treble sections, the front "duplex" length is very close to the length
of the speaking length of C8.  This arrangement produces a rather pleasant
and unusually clean high treble.  Perhaps it has more to do with the
smaller angles of deflection than the lengths defined, but in any case,
there is none of the objectionable stuff produced by the termination piece. 

> Laying in a half round of 
> appropriate depth to provide a second counter bearing and 
> effectively shortening the front duplex to 10mm clears up all 
> the objectionable front termination generated garbage (which 
> is substantial) and leaves the thing sounding as clean and 
> pretty as the rest of the piano allows.

Brilliant!  I wish this idea had come to my attention when I was in a
position to implement it.

> As a means of tying 
> the capo to the plate flange for increased stiffness, I think 
> these were a very good idea just not well implemented.

yep

I have a final observation about termination pieces.  I don't know what
this might have to do with the price of tea in China, but I find it very
curious.  In a piano with a traditional v-bar, if you pluck the front
duplex, the most prominent frequency that you hear is that which is defined
by the front duplex length (as you might expect).  When you pluck this
length within a termination piece, the more prominent frequency you hear is
that of the speaking length!  What's with that? 

Frank Emerso