h'chord LM

[fssturm@unm.edu]

    I'll echo Dave Doremus. The issue of how far a key should depress 
before the plectrum comes in contact with a string is definitely not a 
simple one, and if you have never staggered a set of jacks (meaning 
adjusting bottom screws - if the jacks have bottom screws - so that the 
choirs of jacks pluck in order, evenly spaced), you should probably 
avoid messing with them. 
    In general, when the harpsichord is fully coupled (all choirs of 
jacks engaged) one wants the first jack (usually 4 foot) to pluck 
almost instantly - just enough play to allow plectrum to get below the 
string and not buzz, with a bit of slack for humidity change. Then one 
wants the back 8 foot to come in contact just as the 4 foot completes 
plucking, and the front 8 foot to contact when the back 8 foot has 
completed plucking. This varies dramatically with how long the plectra 
are (which is affected by how evenly the nut bridge is pinned), how 
much the plectra extend under the string, and how strong/weak the 
plectra are. 
    Once you have well-staggered jacks, the "lost motion" for each 
choir should be pretty even from note to note (assuming you have a well-
finished instrument with even string spacing and evenly cut and voiced 
plectra), but it will vary a lot from choir to choir. Often the upper 
keyboard (usually the front 8 foot) will have quite a distance before 
plucking, due to being the last in the staggering order plus any lost 
motion between lower key and upper when they are coupled.
    Bottom line: there's a lot to learn before one should plunge in and 
do turn screws (one reason David Way decided not to have bottom screws 
on Zuckermann jacks - so the inexperienced wouldn't "screw" things up, 
as he put it). It's not all that hard to do - just like pianos, one 
must be finicky and consistent, and understand how one step affects the 
next - but it requires experience to do well.
Regards,
Fred Sturm
University of new mexico
Quoting Dave Doremus <algiers_piano@bellsouth.net>:

> At 4:08 PM -0500 3/19/03, Ed Sutton wrote:
> >Hi, Dave!
> >     What would you think of "the jack needs to apply pressure to
> the string
> >with the damper, and also just barely be touching the key cloth?"
> 
> Hi back at you, Ed. I would point out that that would be true in the
> 
> case of the 4' (if you pluck 4', < 8', >8') but the others would be 
> higher by a turn or two of the screw in order to follow the first. 
> And if you transpose you cant have any jack getting caught in the key
> 
> end cloth as you slide the keyboard over. I have no problem with 
> Richard Kingston, he makes very nice instruments, which is more than
> 
> I can do, but I learned to regulate and voice from someone I think is
> 
> much better. I have cut jacks to samples top and bottom (c's and f's
> 
> usually), turned in screws to match a bench guide and never once has
> 
> it been perfect. It will get you close. The jack rail needs to be 
> padded and shimmed as the last step. I have found that the short cuts
> 
> schemes are OK but not quite there. Several very good harpsichord 
> builders have argued that you can voice by using gram weights on the
> 
> keys to get an even touch, one used to grade his delrin in different
> 
> strengths, claiming no voicing necessary. Again, often close but not
> 
> quite. I do not think that shimming the keyboard is considered 
> necessary by the best bulders, (I may be out of date on this), 
> although your overlap will change and the jack rails may have to be 
> adjusted and that is where the jack adjusting screws can be useful. 
> But many times owners and others take it into their heads to play 
> with those, causing the poor technician even more headaches. Let me 
> mention that none of these modern improvements are present in the 
> originals which limped along quite nicely without all the
> adjustments.
> 
> ----Dave
> 
> 
> -----------------------------
> Dave Doremus RPT
> New Orleans
> algiers_piano@bellsouth.net
> ------------------------------
> 
> -- 
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