Wound Trichords

[Erwinspiano@aol.com]

---------------------- multipart/alternative attachment
 

List 
   I too am not a fan of trichords but the trichords on S&S  D' do not bother 
me aurally & no doubt lends to there power & unique  sound. By now some one 
has surely rescaled this piano with bichords for the top  7 bass trichords & 
has an opinion as to the sound?
   The only spot I've ever employed tri-chords with success is on  the first 
2 tenor notes of Mason BBs & S&S B. On the S&S B the  tension is sooo low, 
ie.105 lbs per string at note 21. INstalling these 2 notes  as  wrapped tric 
-hord unisons gets the tension up into the 140 lb range  & provides for a quite an 
improved good transition from bass to tenor.  Not perfect though.
    Also as RonN points out  it's a difficult string to  wind & get right. 
And such is the case that now  GC will no longer make  them for me so I called 
Arledge. God bless him, he's willing to try anything. I  love a can do attitude.
  I was told by my bass string maker that this spot on both pianos is  too 
long for bichords. Any one else confirm this?  The B  really needs  about 5   
pair of bi-chords liike the S&S A's & no doubt  a shorter in length & placed 
transiton bridge.
 I recently put a new belly in a 6 ft Weber that had 4 pair trichord  in the 
top end of a 26 note bass. They sounded  poor. I  rescaled it  for bichords 
with good success. I filled the extra plate holes with appropriate  sized rubber 
buttons. & it looks fine. 
  Good discussion. Enjoyed it.
    Dale Erwin
   


Not  a bad idea so much as a less than ideal fix. Putting the wrapped 
bichords  on the low end of the tenor bridge will likely make it less bad, 
if it can  be made to fit into the scale. For instance, that 38.75" C#-3 
with plain  wire trichord will be at about 24% of breaking tension 
(regardless of wire  size, within reason). That's pretty low, and will be 
very reactive to  tension changes resulting from humidity fluctuations, 
meaning it will go  out of tune quicker and farther than unisons farther 
up-scale, or down  scale in the high bass. Tension will be determined by the 
wire size used  there. For instance, unison tension with #20 will be about 
404 lbs, or  about 369 lbs with #19. Going to a bichord unison, dropping two 
or three  half sizes for the core, and figuring wrap to get back near the 
unison  tension that was originally there will raise the break% to around 
40%.  That's going to be a more stabile unison with humidity changes, and 
sound  better too. The trouble is, that puts you at the bottom of the list 
of  available copper wrap sizes, requiring about a 0.007" wrap to keep the  
tension down around where it was with the plain strings. Arledge uses as  
small as 0.006" for copper wrap. That takes care of C#-3, if the impedance  
and inharmonicity connects reasonably with the high bass. Now you'll  
probably want to go 2-4 notes higher with wrapped bichords to blend the  
impedance and inharmonicity into the rest of the treble. What happens? You  
maybe need 0.006" wrap for D-3, and smaller than is available for the next  
one or three. There's the problem, and the reason this doesn't always work  
that well, and the reason for transition bridges. The speaking lengths are  
too long at that pitch for wrapped strings. What you can get away with  
depends on the individual scale and what you have to work with.

Ron  N


 

---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/c3/e9/11/cc/attachment.htm

---------------------- multipart/alternative attachment--