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From: Patent Tactics, George Brock-Nannestad

Friends, it was great to see some of you, if briefly, at the ARSC  Convention
in Philadelphia. Nice to put faces to names you have  only seen on the list.

On 10 Jun 2003 at 9:18, Mike Richter wrote:

> James L Wolf wrote:
> >Steve, (meaning Steven Smolian)
> >
> >     Can a cartridge wired this way produce a stereo signal reflecting
> >right and left groove walls? Or does any stereo cartridge rely on
> >vertical movement? Thanks.
>
> No, a stylus wired to sum left and right channels as recommended will
> provide only a monaural signal. (That remains true even if both channels
> are driven.) It is a quick and easy solution to reducing vertical rumble
> and related faults but works as intended only if the two channels are
> perfectly balanced. In the real world with unbalanced channels, the result
> is as though a monaural cartridge is slightly skewed in its mounting.
>
> All stereo cartridges rely on vertical and horizontal displacement to get
> the separate channels.
>


----- I must take exception to that. Since 1957 most stereo  cartridges have
relied on having one set of coils sensitive in a  slanted direction 45
degrees to the right and another set of coils  sensitive 45 degrees to the
left of vertical. The stereo information in  such stereo records are cut for
those directions, termed right and  left channel. Blumleins own design was
for vertical and horizontal  (lateral). You can obtain one type of signal
from the other type by  so-called  matrixing, in which you add and subtract
the signals  suitably. For 45/45, I obtain lateral mono from a stereo output
by  summing the signals from the coil sets, and I obtain vertical mono  by
taking the signal in the reverse from one of the coil sets and  summing
(series connection is summing). I have built in a hearing  aid switch of
negligible weight into one of the headshells I use for  performing this
reversal of one coil connection.

Now, the channel separation of a stereo cartridge is rarely more  than 20 dB
over a wide frequency range. For this reason there is no  way to obtain a
pure vertical or a pure horizontal signal by summing  as described, not even
with a balancing control. The only way to  obtain that is to use a mono
pickup. And here Ortofon have a genial  solution: they have revived a
cartridge from 1949, it is dynamic  (moving coil), and it has a high vertical
compliance. That will give  pure lateral mono, except for pinch effect, which
is reduced if you  use an elliptical stylus that is oriented as the cutting
stylus was -  vertical tracking angle has to fit as well as any rotation of
the  original cutting stylus in its holder. If you want to use several kinds
of stylus on this cartridge it is going to be expensive.


Kind regards,

George