From: Patent Tactics, George Brock-Nannestad
Hello,
there were two kinds of bifurcated stylii (to give them the correct
designation). One was for playing a negative and one was for polishing away
little crystal growths. The former would not damage a negative. And
incidentally: the negative is very, very sensitive to damages to the "active"
surface. It is not like a positive, where the information is well protected
because it is dug into the material.
Offhand I cannot remember which was which, but there were two fundamental
patents on bifurcated stylii. One type was by George Alexandrovitsch (I
probably can't even spell his name right!). One was one diamond with a sort
of screwdriver end, into which a notch was polished, with rounded edges so
that it could straddle the ridge that is the negative of a groove. The other
was a composite of two diamonds side by side, each being a cut-off of a
"normal" conical stylus. They met in such a way that the V between them had
the appropriate radii of curvature.
The one that Expert Stylii could make would be the latter. However, due to
the increased weight of the stylus, it would probably be advisable to use
half-speed or less reproduction, and that would also throw the rumble further
into the insensitivity of a dynamic pickup.
For those who do not wish to venture into the manufacture of new bifurcated
stylii (and stocks have been depleted), I have a suggestion which I have
tried once. That is to use a broad truncated elliptical stylus to play
between two ridges: in effect a groove. In a stereo pickup, one channel is
one flank of one ridge, and the other channel is the opposite flank of the
neighbouring ridge. I only tried it before DAW became widespread, so I only
listened to one channel. But it ought to be perfectly feasible to delay one
signal one revolution with respect to the other and to re-synchronise. This
works best with a ridge that has a 90 degree top (modern groove). For earlier
grooves, which were very steep near the land, there is a risk of wear when
you play a negative this way with a stylus that is not broad enough, because
the vertical work will be considerable. The advantage of this process is that
there is no careful straddling to be done; the stylus stays put.
Kind regards,
George
> >White man speak with forked needle. What does this mean?
> >Cary Ginell
>
> >> But, playing metal parts with fork needle - is it kind of
> >> damaging them? No?
> >> Milan
>
> Metal parts are negative images, thusly must be played with
> a forked needle. Ask Seth Winner..
>
> -Matt Sohn
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