[pianotech] Finger Cymbal Sounds Answer

[Ron Overs]

Steven,

>Thanks to all for the suggestions.  In the end it was duplex noise.

I've been following this thread, expecting it to be duplex noise. If 
the C7 is thirty years old I think it will be a C7B. If it hasn't 
been re-strung it will be due for it. But it likely will have a dead 
board in the first capo string section. Furthermore, the scale 
lengths at F21 are far too short in this piano (no 7 foot piano with 
a plain wire F21 can work), so it would benefit from a tenor bridge 
if and when it is rebuilt. The C7F was a major scaling improvement, 
with a 23 note bass which resulted in G#23, the first note on the 
long bridge, having a percentage of break at around 36% (the same as 
the 183cm F21 first long bridge note on the S&S model D). The note 
F21 on the C7B had a percentage of break in the low twenties. It was 
gutless on that note and refused to stay in tune if the weather dared 
change. Just turning on the air conditioning in the room was enough 
to completely stuff the tuning. All the C7 pianos before the C7F 
broke at E20/F21 and were a scaling mess, whereas the C7F is quite a 
respectable instrument compared to many other offerings in the 7 foot 
class.

>Once muted everything was fine.

Well sort of. The muting will tend to kill the duplex noise, but it 
will also be damping all energy which bleeds across the capo to the 
duplex segment. This will result in less sustain for those notes 
which have damped duplex segments.

>   I thought it was in relation to my filing and voicing but I now 
>realize that we had just moved this piano from a proffessors small 
>office to an auditorium.  I believe the acoustics are what helped 
>pronounce the noise which was probably already present in the small 
>room but was not as audible?  I will know for sure when we move it 
>back after the recital Sunday.

Indeed. Its likely that the professor's room be will less lively at 
around 3.5K, relative to the auditorium, which will allow you to hear 
the duplex noise more easily in the auditorium.

>It is interesting that the proffesor did not hear the noise until I 
>pointed it out to him while explaining the "funny" mute job in the 
>non speaking length of the strings.

The prof's ears might have done a bit more work than yours, and he 
very likely has considerably more roll off. Older ears, in general, 
are less likely to hear duplex noise.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
_______________________