If you’re a vinyl enthusiast, you know that the quality of your turntable’s sound depends on a variety of factors. One of the most important components is the phono cartridge.
But what exactly is a phono cartridge, and how does it work?
In this article, we’ll dive into the basics of phono cartridges, including their purpose, construction, and different types available on the market.
Whether you’re a seasoned collector or just starting out, understanding the role of your turntable’s cartridge is crucial to getting the most out of your vinyl listening experience.
So let’s get started!
What Is A Phono Cartridge
A phono cartridge is a small electro-mechanical component that is mounted at the front of a tonearm on a turntable. It consists of two main sections: the cartridge body and the stylus assembly.
The cartridge body houses the wire coils that generate the electrical signals, which are then transferred via the tonearm wires to the phono stage in the amplifier. The stylus assembly consists of a plastic molding with a cantilever (or tube) and stylus (or needle) which vibrates as it traces the record grooves. The stylus is the needle-shaped tip of diamond at the front end of the cantilever.
The performance potential of a record playing system is defined by the capabilities of the phono cartridge. Tonal balance, response range, clarity on musical peaks, stereo separation and imaging, and freedom from noise and distortion are all affected at the outset. The selection of this first component is critical to the full enjoyment of the rest of your system.
The Purpose Of A Phono Cartridge
The purpose of a phono cartridge is to convert the physical movement of the stylus in the groove into electrical signals that are then amplified and sent to speakers for us to hear. The technical function of a cartridge is a “transducer” since it converts energy of one form (the physical modulation of a groove) into another form of energy (electrical voltage).
The phono cartridge is arguably the most sonically critical part of a record player since it directly affects the sound quality. The tonal balance, response range, clarity on musical peaks, stereo separation and imaging, and freedom from noise and distortion are all affected by the phono cartridge. Therefore, selecting the right phono cartridge is critical to the full enjoyment of your record playing system.
The cantilever end of the stylus arm actually contacts the record grooves, which pick up the vibrations. These vibrations are then carried up to a moving magnet assembly in the cartridge where the voltage is created. The cartridge body houses the wire coils that generate these electrical signals, which are then transferred via the tonearm wires to the phono stage in the amplifier.
How A Phono Cartridge Works
The phono cartridge is responsible for transforming the undulations in the record groove to electrical oscillations that are then amplified in an amplifier to finally drive the loudspeakers in the HiFi system. The cartridge works by using a diamond stylus that mechanically follows the record groove, transmitting its modulations via a cantilever to a miniature generator, which in turn transduces the mechanical movements into electrical currents/signals.
When the stylus traces the movements of the grooves, it vibrates the cantilever. The rubber suspension allows the cantilever to pivot so that the stylus can accurately track the grooves. Vibrations from the stylus tip travel along the cantilever to the magnet. As the magnet vibrates, its magnetic field varies. These variations in the magnetic field generate a small voltage in the coils, which corresponds to the movement of the magnet.
This signal is then passed through a phono preamp (for RIAA equalization) before reaching the amp/speakers, which convert the electrical signal into sound. To get a stereo signal (left and right channels), this configuration is essentially doubled. Two magnets are attached to the cantilever at a 90-degree angle each with a corresponding set of coils.
Construction Of A Phono Cartridge
The construction of a phono cartridge is a complex process that involves precise engineering and the use of high-quality materials. The stylus is the only part of the cartridge that makes contact with the record, and it must be made from the hardest material known to man – diamond. The stylus construction and shape are also crucial factors in sound quality.
There are two common types of stylus: bonded and nude. Bonded stylus is a more cost-effective option used in entry-level cartridges. It consists of a diamond chip attached to a steel shank, which adds mass to the cartridge and is not ideal for high performance. On the other hand, a nude stylus has a shaped diamond attached directly to the cantilever, which is a superior way to transfer the kinetic energy that creates the signal. Although it costs more than a bonded stylus, it can significantly improve your listening experience.
Moving magnet and moving coil cartridges are the two common types of pick-up cartridges in use today. In a moving magnet cartridge, the diamond is attached to a rigid cantilever, which is controlled by a suspension system. The movement of the cantilever causes a magnet attached internally to it to move, interacting with coils of fine wire inside the main cartridge body. This creates an electrical current that represents the original music signal.
In contrast, moving coil cartridges use a lighter moving system, allowing for easier and more fluid movement of the cartridge’s components. The coil is attached to the cantilever system, while the magnet sits within the main body. The electrical generation is the same as in moving magnet cartridges; however, because moving coil has less mass, its output is typically lower.
The construction and design of phono cartridges vary depending on their type and quality. For instance, Decca phono cartridges were unique in design, with fixed magnets and coils. The stylus shaft was composed of a diamond tip, soft iron, and an L-shaped cantilever made of non-magnetic steel. The iron was placed very close to the tip (within 1 mm), allowing for accurate tracking of tip motions referred to as “positive scanning.” Vertical and lateral compliance were controlled by the shape and thickness of the cantilever.
Moving Magnet Vs. Moving Coil Cartridges
When it comes to phono cartridges, there are two main types: moving magnet (MM) and moving coil (MC). The main difference between these two types of cartridges is how they function mechanically. MM cartridges have static coils and a moving magnet, while MC cartridges have a magnet that stays still while the coils vibrate.
One of the advantages of MM cartridges is that they are generally less expensive than MC cartridges. However, they do have some drawbacks. For example, MM designs are heavier than MC setups and exhibit greater inertia when it comes to reading the subtle changes within the grooves. This means that MM designs are less competent at tracking very high-frequency content, and therefore some listeners may feel they lack transient detail.
On the other hand, MC cartridges are preferred among audiophiles in large part because they use far less moving mass. With less mass bearing down, the stylus and cantilever are more nimble in the record groove, which in turn allows the stylus to reach more of the surface area therein (and to react accordingly to it). It should be noted here too that less moving mass makes the job of the suspension much easier, improving tracking ability. As a rule, MC cartridges are far lighter than MM designs and can achieve ‘better’ sound quality because they’re capable of transcribing more micro-detail, particularly in the high frequencies.
However, there are some drawbacks to MC cartridges. They are more complex and difficult to maintain unless you’re an expert. This is partially because the mechanism that moves coils is lighter and more intricate than one that moves magnets. Because of their lightness and intricacy, MC cartridges are more precise and create a more delicate sound. They also cost more to manufacture and upkeep than MM cartridges.
Other Types Of Cartridges
Apart from the three main types of cartridges mentioned earlier (moving magnet, moving iron, and moving coil), there are other types of cartridges available on the market. One such type is the ceramic cartridge, which was popular in the 1950s and 1960s. Ceramic cartridges are less expensive than other types of cartridges, but they tend to be less accurate and have a higher level of distortion. Another type is the optical cartridge, which uses a light beam instead of a stylus to read the record groove. Optical cartridges are known for their low noise levels and high tracking ability, but they are less common and tend to be more expensive.
Another type of cartridge is the strain gauge cartridge, which uses a different method for generating electrical signals. Instead of using wire coils, strain gauge cartridges use a small piece of metal that is attached to the cantilever. As the cantilever vibrates, it causes the metal piece to bend slightly, changing its electrical resistance. This change in resistance is then converted into an electrical signal. Strain gauge cartridges are known for their high accuracy and low distortion, but they require a specialized preamp to work properly.
Finally, there are also hybrid cartridges that combine elements from different types of cartridges. For example, some hybrid cartridges use a moving magnet design for the lower frequencies and a moving coil design for the higher frequencies. These hybrid designs aim to provide the best of both worlds in terms of accuracy and sound quality.
When choosing a cartridge for your turntable, it’s important to consider your budget, listening preferences, and system requirements. Each type of cartridge has its own strengths and weaknesses, so it’s worth doing some research and listening tests before making a decision. Ultimately, the right choice will depend on your individual needs and preferences.
Choosing The Right Cartridge For Your Turntable
When it comes to choosing the right cartridge for your turntable, there are several factors to consider. The first decision you will need to make is whether to go for a moving magnet (MM) or moving coil (MC) cartridge. MM cartridges are more common, have a higher output, and are typically sturdier in design. They are also easier to replace the stylus on. On the other hand, MC cartridges are less heavy which results in a more detailed and accurate sound, but they are also more delicate and require replacing the entire cartridge when the stylus wears down.
Another important factor to consider is the shape of the stylus. Elliptical styli have a smaller contact radius than conical styli, which allows them to trace grooves more accurately and extract more musical information, especially high frequencies. However, they wear down faster than spherical/conical styli, which put more pressure onto the record and have a smaller contact area.
The cantilever is also an important consideration. It needs to be as stiff and light as possible to effectively transfer vibrational energy from the stylus tip to the magnet or other generating element. Aluminum alloy is the most common material used in cantilevers, although carbon, boron, and certain copper alloys are often used.
Finally, trackability is an important spec that describes how well the stylus can track a modulated record groove. It is influenced by many factors, including stylus shape, cartridge alignment, and tonearm compatibility. The higher the trackability spec, measured in micrometers (μm), the better.
When choosing a cartridge system, it is advisable to either test them in person or make sure that the online description matches what kind of sound profile you are looking for. Ultimately, the right cartridge for your turntable will depend on your personal preferences and budget.