Everything you always should have known about pick-up cartridges*
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*But didn't know to ask
Think about this: if you play records and you have a marvellous turntable, a
magnificent amplifier, great loudspeakers and a poor cartridge, the sound will
be as good as... the cartridge. Yet a cartridge is often chosen with much less
care than the other components of a music system.
Music enthusiasts and high fidelity cognoscenti agree: the cartridge,
positioned in the tonearm of the turntable, is the key factor in the
reproduction of musc from records. After all, it makes the first and only
contact with the record. Thus, cartridge quality determines sonic performance
even before sound is amplified and played through your loudspeakers. We know
that two things would happen if music lovers knew more about cartridges in
general. First, their music systems and their enjoyment of music would be
significantly enhanced. Second, Ortofon cartridges would be part of even more
music systems around the world. To understand how important the cartridge is to
any music system we must know a little more about records.
First, Making the Tape
Just how does music get on a record? Well, first there is the musical
performance which is put onto tape. Often, each instrument and/or singer is
given a separate microphone and a separate channel. Professonal tape recorders
may have as many as 32 channels. Thus, the sound of each instrument can be
individually balanced, adjusted, and enhanced. Different channels can even be
recorded at different times. Now all of the channels recorded in the studio
have to be "mixed down" into one stereo channel before a record is cut. At this
mixing stage, record producers make many of the decisions that determine the
sound quality of a performance. The 2-channel master tape with the balance,
adjusted and enhanced sound of all 32 channels is then used to make the master
disc from which all other records are made.
Making the Record
When the tape is played, its magnetic patterns are converted into electrical
signals and sent to a cutterhead (on a lathe). The cutterhead converts these
signals into mechanical motion causing a cutting stylus to move as dictated by
the signals on the tape. Thus, an incredibly complex groove is inscribed into a
master disc. Moulds are then made from which the records in your home are
stamped.
How to Get the Music Out
You might imagine many different ways to extract the music from the record
groove. But, in fact, the only way is with a pick-up cartridge. A cartridge
consists of three basic elements.
One of these is the stylus (needle) that traces the record groove. Another is
the cantilever, the part on which the stylus is mounted. The third is the
generating system that converts the motion of the stylus and cantilever to
electrical replicas of the sound and sends it on for amplification.
The stylus
The stylus is the only part to make contact with the record. A force must be
exerted by the tonearm to keep the stylus in the groove when the record is
spinning.
This tracking force is usually low, between one and two grams.
But, because the stylus makes contact with less than one millionth of a square
inch of the record surface, it exerts a tremendous pressure: 6000 pounds per
square inch! At such enormous pressure, any roughness or irregularity in the
stylus would cause record damage. The stylus must also be hard or it will wear
out quickly. For these reasons, high-quality styli are made from the hardest
material known to man: pure diamond.
The Shape of Things Right Now
There are three commonly-used shapes for styli. The spherical (also called
conical) shape is the least expensive to manufacture, and is commonly used in
low cost cartridges. Unfortunately the spherical stylus can not trace the
highest musical tones accurately.
The more expensive elliptical stylus, has a narrow profile enabling it to follow
the petite undulations of the groove with greater precision. It is used in the
majority of high quality cartridges. A third stylus shape, which Ortofon calls
the Fine-Line, provides more faithful tracking of the groove. It has an even
narrower profile than the elliptical shape. It makes contact with a wider area
of the groove, reducing the tremendous pressure the stylus exerts on the
delicate record surface. Thus, the Fine-Line shape reduces record wear.
The Naked Truth
Because diamonds are so expensive, they are positioned only at the extreme tip
of most styli and are glued to another, less expensive material which makes up
the rest of the stylus.
The finer cartridge has a stylus of pure diamond. This is called the nude
diamond stylus. Such a stylus provides the lowest possible moving mass, and
crisper, more accurate response, especially in the upper registers of the music
The Cantilever
Now that we've got this precious diamond moving at tremendous speed through the
complex groove of a spinning record, what transmits its motions to the
generating system?
The cantilever. In order that the cantilever may relay the rapid movements of
the stylus, it should be light weight so it can respond rapidly to the twists
and turns of the record groove. But it must be rigid, for any bending or
flexing would add distortion and sound colouration. Obviously, light weight and
high strength requires great ingenuity in design and materials.
The Generating System.
High fidelity cartridges are based on this law of physics; when material capable
of conducting electricity is set into motion in a magnetic field... or when a
magnet is moved near such conductive material (copper coils), electrical
voltage is generated. The direction and speed of the movement determines the
amount of voltage.
Thus the generating system of a cartridge converts the movement of the stylus
and cantilever into a voltage we call the output signal. There are three ways
of doing this
1. Moving the magnet
The most common generating method is to mount a magnet on the back of the
cantilever. As the motion of the stylus and cantilever causes the magnet to
move, the magnetic flux changes in the nearby coils, and voltage corresponding
to the changes is generated.
Moving magnet cartridges are less costly to manufacture since the coils can be
machine-wound. They have high output, and when the stylus wears out, you simply
slide the old stylus assembly out of the body of the cartridge, and slide the
new one in.
2. Moving the Iron
To improve tracking of the groove and achieve lower distortion we must lower the
mass of those parts of the cartridge that move - the "moving-mass". We can
remove the magnet from the rear of the cantilever as in the moving magnet
types, and substitute a tiny, very light, hollow piece of iron.
That iron would move in the field of a stationary magnet, changing that field
and generating a changing voltage in the coils. Voila! Lower mass, better
tracking, lower distortion with all the advantages of the moving magnet types:
moderate cost, high output and slide-in/slide-out stylus assemlby.
3. Moving Coil
The most sophisticated - and most expensive-way to generate voltage is the
moving coil system. Insted of a magnet or iron, carefully hand-wound coils are
mounted on the cantilever, and move in the field of a stationary magnet.
Voltage is generated directly, with a minimum of distortion. To keep moving
mass as low as possible, there are usually very few turns of the coil. For
example, stationary coils (as in moving magnet or moving iron cartridges) may
have as many as 3,000 turns of wire - the moving coil, only 15 or 20. But fewer
turns mean lower output voltage.
So unless your amplifier is already designed to work with such a cartridge, the
best moving coil models require an accessory that boosts output- a preamplifier
or a step-up transformer. Also, because the coils are part of the moving
system, the stylus usually cannot be replaced without disconnecting the tiny
wires inside the cartridge - a job for a technician. With all these
"requirements", why are moving coil cartridges so desireable? Performance.
Moving coil cartridges have a distinctive, unmatched musical sound. This may be
because the recording cutterhead also operates on the moving coil principle,
and the moving coil playback cartridge provides an exact complement - or it may
be because the voltage is generated directly in the coils. But moving coil
cartridges consistently win acclaim as the finest in the world.
Taking It Lightly
When the moving parts of a cartridge (the stylus, the cantilever and the moving
magnet, iron or coil) are low in mass they respond more faithfully to the
undulations of the record groove. Only when moving mass is low will the record
be safe from premature wear or damage.
While low moving mass is critical, low mass in the cartridge's fixed parts is
also a factor in the reproduction of music from records. That's because all
records are warped to some degree. Some warps are obvious and can be spotted by
the naked eye, but most are not easily seen - the tiny bumps and warps that
are"manufactured" into the record, together with eccentricities caused by
imprecise centering of the record hole. As it goes over a bump or warp, the
stylus of a high-mass cartridge responds to the warp as well as to the music.
When the cartridge climbs towards the crest of the warp, the stylus is
compressed towards the cartridge body. As the cartridge descends the far side
of the warp, the stylus is extended away. This motion causes the cartridge to
generate unwanted signals, and a host of related problems.
Mistracking: as the stylus is compressed and extended, it alternately digs into
the record groove, and pulls away from it. The stylus can even leave the groove
altogether. Premature wear: such stresses shorten both the record and stylus
life. In fact, mistracking can damage a record in a single playing. Distortion:
the unwanted signals of record warp get mixed with the recorded music, causing
audible intermodulation distortion. For these reasons, turntable manufacturers
have made low cartridge/tonearm mass a top design goal.
But their efforts have been limited by a simple physical fact. The tonearm is a
lever. The parts farthest from the pivot make the greatest contribution to
effective mass. Because the cartridge is located at the end of the tonearm,
lower cartridge mass is the most effective way to achieve low mass in the
entire cartridge/tonearm system.And low system mass means better tracking,
reduced record wear, and cleaner, clearer sound.
Finding a Perfect Match
Because the tonearm is "suspended" on the stylus/cantilever during record
play, and because the cantilever has a spring-like action, they form a
vibrating system. Like all vibrating systems, this one has a favourite place to
sound off. It's called a "resonant frequency." Obviously it's important that
the resonant frequency - the sounding-off point - of such a vibrating systm
fall in a "safe" range above the frequencies of record warp and below the
frequencies where the music takes place. The only way to avoid this is to
carefully match the compliance - "springiness" - of the cartridge's cantilever
with the weight of the cartridge, headshell and tonearm. Here the advice of a
knowledgeable dealer (like one selected by Ortofon) or an audiophile friend is
invaluable.
Ortofon High-Output Cartridges
Ortofon offers three series of high output cartridges. The low mass, LM
series provides astonishingly reduced mass.
The standard-body VMS Series offers superb performance at modest cost. The
Concorde Series, ideal for universal-mount tonearms, combines a cartridge and
headshell in a single entity, yet each model weighs less than most cartridges
or headshells alone! There is an Ortofon model with the correct compliance for
every tonearm
The VMS System
All Ortofon high-output cartridges share the extraordinary performance of the
patented Variable Magnetic Shunt (VMS) generating System. With VMS, a
minuscule, hollow armature moves in the field of a tiny, stationary ring
magnet. When it moves, a portion of the magnetic field is shunted
(short-circuited) causing voltage to be generated in nearby coils. (Diagram
shows one channel only).
VMS provides unparalleled tracking ability, reduced distortion,
high output, consistent separation and high frequency clarity.
Moving Coil Cartridges and Accessories
Ever since Ortofon patented the moving coil cartridge in 1948, it has
retained leadership in moving coil design. Moving coil
playback cartridges are the only type that are precise complements, of the
moving coil recording cutterhead, so it is no accident that the Ortofon Moving
Coil Cartridge Series is the most highly acclaimed in the world.
And, if your amplifier does not already have a built-in step-up device for
moving coil cartridges, it's a good idea to examine
Ortofon's full line of high-performance, step-up transformers and
pre-preamplifiers.
A Little about Ortofon
As far back as 1945, Ortofon established a reputation as the leading designer
and manufacturer of the cutterheads that inscribe master records. But the phono
playback cartridges of that time just were not good enough to test our
cutterheads for low distortion and wide frequency range. So we made our first
playback cartridge for ourselves. Not long afterward, we offered Ortofon
cartridges to the public.
To this day, Ortofon is the only company that makes both recording cutterheads
and playback cartridges. And, because of the skills involved are intimately
related, Ortofon maintains a unique advantage over competitors.
The Final measure
The final measure of any cartridge is sonic performance. In this respect,
Ortofon has earned the most enviable reputation in the world. Musicians, music
lovers and critics agress - an Ortofon cartridge means that records can be
played with exquisite fidelity.
The 5 Golden Cartridge Rules
- It always pays to change to a better cartridge. It is the component in a
Hi Fi system that makes the first and only contact with the record groove. So
it can never be too good.
-
Be sure to choose a cartridge with a compliance that matches your type of tonearm
-
Never play old or damaged records with a new cartridge. This may ruin the
diamond stylus which in turn will spoil your new records.
-
Remove dust from records and stylus each time you play. When necessary, use
a recommended cleaning fluidd.
-
Have your cartridge checked regularly (at least once a year) at a good Hi Fi dealer.