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.