further remarks.

[clifford wright]

Thank's for the replies. But I'm afraid you are WAY off timewise.
Many years ago I actually had a couple of early "balanced armature" magnetic
pickups. They were @$%#@##$ enormous with a tracking force measured in
pounds! Being hi Z they produced an output nearly as high as a high output
ceramic.
"Crystal" pickups were common in my own youth over 50 years ago, but I've
never seen any pre WW2 ones. I still use a later one to make CD's from my old
78 collection.
I guess one of those early 30's pickups would be reasonably OK but to keep in
period it may yet come to the old carbon button mic in an old acoustic arm,
which was used very early on occasionally.
Research will continue.
Clifford Wright Helensville New Zealand.

[Richard Knoppow]

"clifford wright" <c.c.w...@paradise.net.nz> wrote in
message news:Xns9FE538B2...@216.196.97.131...

I can't find an original post for this.
Crystal pickups became popular about the mid-1930s. The
patents were held by Brush Development Company in the US and
licensed to a number of other companies. Crystal pickups
have the virtue of very high output and very high impedance
so they work directly into the grid of fairly low gain
tubes. The amount of energy they absorb from the record
depends on the design but, in general, the higher the output
the more energy they must absorb and the more the record
will wear. Most crystal pickups were designed for high
output for use in cheap phonographs but a few were designed
for light tracking pressure and wide frequency range.
The balanced armature design can also be adapted to
either fairly high output or high fidelity applications. The
early pickups, dating from the introduction of electrical
recording in the mid-1920s were generally very heavy and had
tracking pressures up to perhaps five ounces. The magnet
materials available at the time did not allow smaller units.
Later developments led to all sort of related devices with
quite low tracking pressures and small sizes. Up to about
the end of WW-2 most high quality pickups for broadcast use
were either moving coil (Western Electric for example) or
ribbon types (RCA for example). But some manufacturers like
Audax made what amounted to moving armature pickups with
fairly light tracking pressure. These older broadcast
pickups typically tracked at around 1oz to 1.5oz, this was
considered light! After the introduction of the Lp record
in 1948 a number of higher quality pickups began to be
available. Some, like the Fairchild pickup were refined
moving coil types but the variable reluctance type, which is
related to the balanced armature type, proved more
economical and some very high performance pickups, like the
General Electric PR series became very popular. The first
ones tracked at around 15 grams (half an ounce) but this was
soon lowered to around 5 grams. In general the forces
involved from 78 coarse groove records required heavier
tracking pressure but pickups like the GE would still
perform well at around 15 grams.
The nature of the stylus support is very important.
Ideally a pickup for lateral records should have very high
compliance for both vertical and lateral motion but no
sensitivity to the vertical component, which in a lateral
monaural recording contains only distortion products. For
vertical (hill and dale) records the motion is almost all
vertical so lateral compliance is of less importance than in
a latera pickup but its still desirable. BTW, vertical
records have an inherent distortion due to the lack of
automatic cancellation of the even harmonic distortion
caused by the difference in tracking path of the sharp-edged
recording styli and the spherical playback styli. This is
aleviated to some extent in both vertical and stereo
recordings (which are a combination of vertical and lateral)
but the use of eliptical styli which more closely resemble
the cutter. A trick sometimes used in vertical recording was
to re-record with the polarity reversed (upward motion in
the original became downward in the copy) in order to try to
cancel some of the distortion. I am not sure how well this
worked or how widely it was ever used. Vertical recording
had a resurgence for transcription use in the mid-1930s
because of the Western Elecric Type 1-A recorder, a vertical
recorder with feedback, the first commercial recorder to
employ it. Despite the advantages of lateral recording this
device was so much better than anything else avaible that is
established vertical recording for a time as a standard.


--

--
Richard Knoppow
Los Angeles
WB6KBL
dick...@ix.netcom.com

[Richard Steinfeld]

On 1/30/2012 1:08 PM, Richard Knoppow wrote:
....
RK wrote a marvelous and informed groove overview. Thanks, Richard.

Let's turn to Clifford's problem and a possible solution.

Clifford, the first thing that you need to do is to determine
what sort of cartridge was used in the original player, or looked
at from the opposite direction, what the input stage needs to
drive it. I think that it's most likely that it was a cartridge
working on the piezoelectric principle: a crystal pickup. Ceramic
elements are latter-day replacements for the old natural
crystals. It's possible that the machine had a klutzy magnetic
design, but there's probably a workaround for a repair.

As we can see from the interchanges between William and Adrian,
the natural crystal cartridges were prone to being damaged by
humidity. Crystal cartridges could fail; the ceramics could fail,
too, but they'd last much longer before they did. The ceramic
elements started coming in during the mono LP era. By the way, my
hunch about these failures is that most of these were due to loss
of good contact between the piezo generator strip and its mating
electrode. In other words, contact contamination. My hunch, too,
is that a late piezo cartridge will probably outperform an early
magnetic cartridge.

So, the first thing to try is to take any record player that has
a piezo cartridge, hook it up to the electronics, put on a
record, and see what you hear from the speaker. At this stage, it
almost doesn't matter what you use. Piezo cartridges were made
with even more output varieties than have been our LP and stereo
magnetic cartridges, because for vinyl records and component
hi-fi, there were actual industry standards that the cartridges
adhered to.

So, if your test cartridge doesn't produce enough output from
your rig, it's probable that a different cartridge with much
greater output will be satisfactory. Richard's cartridge formula
is pretty simple:
Lower compliance, heavier tracking force, stylus jewel coupled
very close to the piezo generator = higher voltage output and
nastier record wear. The shellac records eat up tracking pressure
a whole lot better than vinyl does.

You may even be able to put a modern ceramic cartridge into your
machine, probably even wire a stereo cartridge for mono, and
mount it in an antique arm. Hot glue is your friend!

Richard
Author of The Handbook for Stanton and Pickering Phonograph
Cartridges and Styli.