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George Brock-Nannestad wrote:

> ----- 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.

For totally in phase modulation, mono, then the stylus moves in a pure
lateral or side by side movement.

For out of phase or more correctly polarity flipped signals then the
stylus moves in the vertical or up an down plane only.

For a signal containing left OR right ONLY then weŽd see the above
mentioned 45 degree movement.

So in fact weŽd expect to see movement from all directions inbetween 45
degree slant to side by side depending on the stereo width only.

And for those rare cases where a polarity flipped signal occurs even
vertical modulation will be produced.

So, in fact, a stereo pickup will be able to move in all directions from
lateral to vertical and everything in between.

> Blumleins own design was
> for vertical and horizontal  (lateral).

In British Patent Specification 394,325 of Dec 14, 1931 AD Blumlein
states:

"In all the devices described above, the angles of the axes defining the
movements of the sapphire can be altered by suitably connecting the
windings; for instance, axes which are normally inclined at 45 degree to
the wax surface can be converted into pure hill and dale and lateral cut
axes by arranging that the windings are in series aiding for one channel
and opposing for the other channel. In like manner any axis conversion
can be effected by suitably combining the channels through transformers"

End qoute.

So in fact any movement from purely lateral to purely verical or
anything inbetween not only 45 degrees as implied by you could be had by
the 45 degree mounting arrangement of the driving coils when fed by
varying signals whose PHASE content is different between the two
channels which will produce different VECTOR forces on the cutting
stylus.

> 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).

For the moving magnet pickup cartridge its essential to provide the
correct electrical loading impedance which is set to nominally 47 kohms
loading shunted by 100 to 500 pF of capacitive loading to get the
manufacturer specified frequency response.

Any change from this means a non flat frequency response and should be
avoided if quality results is to be had from the disk to be transferred.

The correct way to do this is to use a phono preamplifier with the
correct replay equalisation for the disk to be replayed and do the
matrixing by mono the left and right signals, L plus R equal to Mono or
lateral sensing, or inverting the polarity of one channel and then
summing, L minus R equal to difference sensing, S, or vertical sensing
only.

This way will not compromise quality.

> 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 channel separation of a stereo cartridge has nothing to do with its
ability to provide pure lateral sensing or vertical sensing.

This is a matter of the phase response between the two channels only and
if they are perfectly alike then pure vertical or a pure horizontal
sensing will be perfect.

Stereo separation by itself can be arbitrarily set by using M/S
techniques to slightly widen the separation to any figure wished for.
But that has nothing whatsoever to do with vertical/lateral sensing as
such.

> The only way to  obtain that is to use a mono pickup.

ThatŽs one way to do it.

Albeit a very good way to do it.

Another way is to simply mono, L plus R, a stereo cartridge.

This will net you a 3 dB increase in S/N compared to any other way and
rid you of boatloads of distortion and rumble and subsonic shit from
warped disks free without the need to filter it out.

> 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.

This sounds wrong to me since no mono cartridge done by Ortofon is
vertical sensing.

I would think that this is correct since youŽre speaking about "> pure
lateral mono"> in the following sentence:

> 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

Pinch effect does NOT excist in mono only pickups. In stereo pickups you
get rid of pinch effect by mono the signal or L plus R.

BTW, the use of an elliptical stylus will negate scanning losses, treble
loss, in the inner grooves near the center of the disk where the linear
velocity is much slower compared to the start of the disk since the
scanning radius of such a tip will better follow the much smaller
curvature of the treble frequencies.

 -  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.

Yes, since you need several such costly cartridges for each stylus size
you wish to use since the stylus cannot be removed from the cartridge
body and changed to a different one as can be done with a moving magnet
cartridge.

--
Best,

Goran Finnberg
The Mastering Room AB
Goteborg
Sweden

E-mail: [log in to unmask]

Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther