The Components of a Turntable

There are a great many record players on the market today, ranging from all-in-1 devices priced from around £30, to high-tech, astronomically expensive audiophile designs that’ll set you back the cost of an upmarket London flat. The models you’ll find in a typical high street big box retailer or on a marketplace such as Amazon will likely belong to the former category.

When choosing a turntable, it’s important to take the value of your collection into account. If you exclusively purchase new records, each record will set you back anywhere between £10-£25, and often more if you spring for limited edition reissues and box sets. The value of a collection quickly adds up, with the cost of 5 new records today averaging around £100.

Of course, used records can be obtained for much less but that doesn’t mean they don’t hold value, especially if they’re in good condition. I’ve been collecting for years and have come across many hidden gems inside job lots often purchased for less than the cost of a single new LP. Some of these records have been valued at hundreds of pounds. It is therefore important that when you consider a budget for a new turntable that you also take into account the monetary and sentimental value of your record collection.

Many of the most popular record players for sale today are of an all-in-1 design, meaning that the record player, amplifier and speakers are housed within the same case, which is usually of a retro design in a portable space-saving form factor. These devices can be purchased for less than £100, which compared to even a budget system comprised of a separate turntable, amplifier and speakers can make them seem like excellent value for money. To assess whether or not this is the case, we first need to see what actually makes a turntable tick.

Components

The Platter

A turntable is a relatively simple mechanical device consisting of a few key components. The first crucial component is the turntable platter, usually topped by a felt or rubber mat to prevent your records slipping or becoming scratched. Those mats serve another purpose too, controlling the resonance of the platter. A good platter should be inert as any ringing can cause a colouration of the sound being picked up by the stylus. Some turntables are designed such that the record can be safely placed directly on the platter with no mat.

The platter’s top surface should make even contact with the vinyl across the entire diameter of the disk. Many records, particularly those released between the 50s and 80s feature a slightly curved lip around their outer edge. Some turntables feature a mat which is slightly curved to match the profile of the record. This offers a stable, flat surface to the stylus to aid tracking.

A good platter should also have high inertial mass. Many platters concentrate their weight towards the outer edge and taper toward the centre. When spun this creates a flywheel effect, much like freewheeling down a steep hill on a bicycle.

The Bearing

Supporting the platter is the main bearing, responsible for ensuring the platter is level and rotates in a smooth, consistent motion. In order for the stylus to accurately track the record, the platter must remain perfectly level during each revolution and must spin freely with minimal drag. The bearing must also run quietly as any residual bearing noise will travel into the platter and into the record, eventually being picked up by the stylus and transmitted through the speakers.

The Motor

Of course, the platter won’t turn without a motor, of which there are a couple of different types. AC motors rely on the alternating current supply from your wall outlet which is supplied at a set frequency depending on your country (50Hz in the UK) to spin at a consistent speed. DC (direct current) motors use a much lower voltage power supply with an electronic circuit governing the speed of the motor. The motor drives the platter either via rubber belt, a rubber idler wheel, or a direct drive system. There is much debate as to which is the superior drive method, but the reality is that there are pros and cons to all 3, discussed in Part 11, Turntable Drive Systems.

The Tonearm

The tonearm, or ‘arm’ sits off to the side of the platter and supports the cartridge and stylus, a typical radial or pivotal arm designed to allow the stylus to trace the record in an arc from its outside edge towards the centre. There are also tonearms known as linear or parallel tracking arms which trace the record from the outer edge in toward the centre in a perfectly straight line, exactly as the record was cut during the manufacturing process. The advantages of this method are detailed below, suffice it for now to say that such tonearms are usually reserved for the highest end turntables, and most of the turntables on the market today feature a standard radial or pivotal tonearm.

A tonearm consists of a few main parts. The headshell is the flat area at the front end of the arm to which the cartridge is mounted. Some arms, particularly those found on traditional DJ turntables such as the Technics 1200, feature a removable headshell to facilitate easy switching between multiple cartridges. Towards the back of the tonearm, you’ll find the bearing which is the point on which the arm pivots. In order to accurately track a record, the bearing must hold the arm steady, as well as provide a low friction pivot point on which the arm can rotate. An arm with a loose bearing will produce chattering, as the arm quite literally shakes as the stylus tracks the record. Chattering causes the stylus to mis-track, losing contact with the groove wall resulting in not only poor sound quality but damage to both the stylus and vinyl. There are technical advantages to having zero play in a tonearm bearing too, covered in this white paper from Rega.

On the back of the arm sits a heavy weight, known as the counterweight. This weight is designed to balance the weight of the arm and cartridge, so as to control the pressure exerted on the record when the stylus sits in the record groove. This is known as vertical tracking force. The goal is to place enough weight on the stylus so that it is able to track the record groove without losing contact, but so that it does not cause undue wear to the record.

The friction generated as the diamond stylus traces the record groove is enough to cause an immense amount of heat at the stylus contact point. The stylus also exerts an enormous amount of pressure on the groove walls. Vinyl is a relatively elastic material meaning that under normal conditions it is able to withstand this heat and force over thousands of plays with minimal wear. However, excessive tracking pressure can scrape away at the walls of the record groove, meaning that the vinyl does not return to its original form causing permanent, irreversible damage. The reverse is also true. To little tracking pressure can cause the stylus to lose contact with the groove walls.

Contrary to popular belief, a stylus tracking too lightly will do far more damage than one tracking heavily, within reasonable levels of course. Record damage caused by mis-tracking is usually visible as white streaks across the record. Too little tracking force can also cause the stylus to leave the groove entirely and skate over the record, usually resulting in a visible surface scratch which will either be heard as a persistent pop as the record plays or may even render the record unplayable.

Many cheaper turntables do not feature an adjustable counterweight, and their tracking force cannot therefore be altered. Some of the cheapest all-in-1 turntables feature no counterweight at all, meaning that the entire weight of the arm and cartridge is placed on the groove, scraping along in the grooves of your treasured records. That’s usually somewhere between 5 to 12 grams, akin to riding a motorbike through soft butter.

A good tonearm will also feature a method of anti-skating, sometimes known as bias adjustment. As the cartridge traces the V-shaped record groove, moving towards the centre of the record, centripetal force tries to pull the arm toward the centre of the record. Anti-skate is designed to counteract this force to equalise the lateral pressure on the walls of a record groove, keeping the stylus central within the V. This not only results in a more balanced sound, but also reduced record wear. Again, cheap all-in-1 turntables don’t feature any form of anti-skate compensation, which essentially means that the left wall of the vinyl groove will wear faster than the right, resulting in a permanent imbalance in the audio channels effectively becoming part of the record.

Linear Tracking Tonearms

As we discuss in section 7, How to Install a Turntable Cartridge, a pivotal tonearm traces the record in an arc, with a couple of degrees of tracking error accept at 2 null points. When a record is cut, the cutting head cuts inwards from the record’s outer edge in toward the centre. A linear tracking arm mimics this motion, offering several advantages. Firstly, there is no tracing error, as the stylus is at all times perpendicular to the groove. There is also no need for bias compensation as there is no centripetal force pulling the stylus toward the centre of the record. Linear tracking arms therefore usually offer superior stereo separation, better tracking and lower distortion over their pivotal counterparts.

However, linear tracking arms bring complexities of their own. The arm itself is mounted to a carriage, which slides along a system of guide rails running on bearings which must be almost entirely free of friction. Some systems utilise an air bearing whereby the arm rides upon a cushion of air. While this means that the arm movement is entirely free of friction, the required pump, tanks, pipework and other hardware take up a considerable amount of room and produce some mechanical noise, which in anything but the largest rooms can be a distraction.

It’s also important that an air bearing tonearm be designed such that the air pressure is equalised across the length of the bearing. Unequal pressure will cause excessive vibration of the arm assembly. Air bearing tonearms are usually reserved for the most exotic turntable systems, though a model known as the Terminator can be had for under £1000 and fitted to just about any turntable on the market.

Other designs run on mechanical bearings, relying on the pull of the stylus to drive the arm across the record. These typically have high moving mass and can if imporperly designed result in excessive record wear to the outer groove wall of the record, not to mention the stylus itself.

Other designs use an electronic control system to drive the arm carriage across the record. A design popularised by Technics in the late 70s which was produced until the late 90s drove the carriage via a small DC motor and a system of gears and drive cord. The arm, which had a small amount of movement in either direction would trigger a sensor as it tracked the record groove, causing the turntable to advance the carriage in tiny steps. This system proved extremely reliable and had the advantage that the tiny stylus wasn’t burdened with dragging the heavy arm assembly across the record. However it did generate some mechanical noise which was sometimes picked up by the cartridge, audible as a tiny thumping during quiet musical passages or blank grooves.

Pioneer’s competing system was similar, though it used electromagnets to move the arm across the record. This produced far less noise and allowed finer control of the arm. Though the electronics involved are extremely complex and thus the reliability isn’t quite as good, many of those turntables are still running to this day.

Today linear tracking tonearms are rarely seen on all but the most expensive turntables. The cheaper Japanese designs have yet to be reborn following the vinyl resurgence, leaving only a smattering of high-end linear tracking arms behind.

The Cartridge

The last major component of a turntable is the cartridge and stylus. The cartridge, which holds the stylus (or needle), is installed into the end of the tonearm and converts the microscopic vibrations of the stylus into electrical energy. The stylus cantilever, which is the tiny shaft that holds the stylus tip itself, is supported by the rubber suspension within the cartridge, allowing it the freedom to move in both vertical and lateral motions. The electrical energy produced by the cartridge is then, via an amplifier, converted into the sound that you hear.

Cartridge Types

There are 4 main types of cartridge in use today, excluding capacitance FM, MMC and optical pickups, all of which are beyond the scope of this article but may be explored in a future post. The cartridges all differ in their mechanical construction.

Ceramic

Ceramic cartridges are the cheapest cartridges in use today. More correctly referred to as a piezoelectric pickup, a ceramic cartridge features a stylus attached to a ceramic rod. The vibration of the stylus within the vinyl groove causes the ceramic rod to bend, thus generating an electrical signal.

Moving Magnet (MM)

Moving Magnet (MM) cartridges consist of a magnet which is mechanically connected to the end of the cantilever, and moves within a pair of coils to generate a stereo signal. A typical moving magnet cartridge tracks somewhere between 1.5 and 2.5 grams, with very few designs tracking above the 3.5 gram mark. Moving Magnet cartridges are found in many hi-fi turntables, and most DJ cartridges such as the legendary Stanton 500 series are moving magnet designs.

Moving Iron (MI)

A Moving iron (MI) cartridge is similar in design to a moving magnet cartridge, though the magnet is substituted for a tiny piece of iron (or another ferrous alloy), which is lighter, requiring less downward tracking force and improving tracking accuracy. A larger fixed magnet positioned over the coils then provides the necessary magnetic field. Few manufacturers offer a moving iron cartridge, though because their electrical characteristics are similar they can be used with any system that can accommodate a moving magnet cartridge.

Moving Coil (MC)

Moving coil cartridges are found in higher end turntable systems and are favoured by audiophiles as they offer greater detail and accuracy. They are essentially an inverted moving magnet design, as the magnet is stationary within the body and the coils are moved by the cantilever. They generate a much smaller electrical signal than their MM counterparts and as such generally require a further stage of amplification, though there are some high output moving coil designs on the market which can be used with a moving magnet preamplifier.

Pros and Cons

There are advantages and disadvantages to all of the above cartridge types. A ceramic cartridge, for example, generates a much higher output voltage than a magnetic cartridge and therefore requires.simpler (and cheaper) amplification circuitry, but simplicity comes at a price. That price is heavy tracking pressure, typically anywhere between 5 and 10 grams. Couple that with the poor quality styli found on many such cartridges, and it’s easy to see why you wouldn’t want one anywhere near your records. They’re typically found in the aforementioned all-in-1 turntables, and should be avoided.

MM, MI and MC cartridges however place far less pressure on the grooves of the record resulting in less groove wear. Further to this, these cartridges are better able to faithfully track the record groove as their designs allow the stylus greater freedom of motion. In a magnetic cartridge, the stylus need only move the comparatively lightweight coil or its housing, and thus is able to achieve a more extended frequency response. However, the stylus of a ceramic cartridge needs to be able to deform the ceramic element enough to produce the sufficient electrical energy, which it cannot. Thus a ceramic cartridge is often unable to accurately reproduce high frequencies, while at the same time producing excessive low frequencies. This is one of the reasons a turntable fitted with a ceramic cartridge usually sounds tinny and lacking in bass.

Ceramic, moving magnet and moving iron cartridges do share a common advantage however, and that is stylus replacements. These cartridges usually feature a removable stylus assembly, which can simply be unclipped from the cartridge body and replaced should the stylus become worn or damaged. Moving coil cartridges however do not feature replaceable styli due to the nature of their design, necessitating that the entire cartridge be repaired or replaced should anything happen to the stylus. Of course there are exceptions to the rule. Some of the cheapest ceramic cartridges don’t have replaceable styli, nor do some higher end magnetic cartridges including those from British manufacturer Rega Research.

The Stylus

Let’s talk for a moment about the stylus itself. Contrary to what many believe, the tip of a turntable stylus isn’t always spherical in shape. This belief stems back to the days when records were played using steel needles, which would vibrate a thin diaphragm, producing an acoustic sound which would be heard through an amplifying horn. When electrical amplification came along so did early Ceramiccartridges with large 3MM styli designed to play back Shellac records. In 1948 the first modern microgroove LPs were introduced, and with them smaller spherical microgroove styli..

These days the tip of a turntable stylus is actually cut and shaped with microscopic precision to one of several advanced shapes, designed to more accurately trace the groove of a record. When playing a modern microgroove record, it is not actually the point of the stylus that is responsible for tracking the record, but instead the 2 sides of the tip which make contact with the side walls of the groove where the stereo signal is imprinted. The deeper the stylus sits within the V-shaped groove, the better its ability to reproduce the musical content of the record.

Spherical Styli

The most common stylus shape is the conical or spherical stylus, which typically measures 0.7 mil (.0007 x .0007 inch) in diameter. It is the cheapest of the stylus shapes to produce, and is typically found on modern ceramic and budget moving magnet cartridges as well as DJ cartridges as it’s the best tip for scratching. Conical styli sit somewhat on the surface of the groove and require a higher tracking force than other shapes.

Elliptical Styli

An elliptical stylus has the same front to back dimensions as a conical stylus, though is of a narrower profile and therefore sits deeper within the groove. They usually require less tracking pressure than conical styli and offer more accurate reproduction of high frequencies. They’re slightly more expensive to produce though not extravagantly so, and there are some very good cartridges including Audio-Technica’s rather exceptional AT95 on the market for less than £30 which feature an elliptical tip.

There are several other stylus shapes including Hyperellipticle, Nude Elliptical, Microline (sometimes known as Micro Ridge) and Shibata. All of these shapes have been designed over the years to combat issues such as inner groove distortion and record wear, and are all of varying shapes and sizes. Such shapes are usually reserved for higher end cartridges however, as they’re costly to produce and require careful setup of the turntable itself.

Stylus Materials

Let’s talk a little about the materials used in stylus construction before we move away from the fascinating subject of styli. There are 2 materials commonly in use today, diamond and Safire. Safire tips are found on the cheapest ceramic cartridges, and some of the cheapest all-in-1 turntables. They’re extremely soft, and will wear to the point where they will cause severe record damage after playing for only 20 or so hours.

Diamond of course is a much harder substance. A properly manufactured diamond stylus can withstand 2000 hours of playback or more. If we assume that each record is around 45 minutes in length, that’s a minimum of 2666 albums. In reality a diamond stylus can last considerably longer if you play clean records and take good care of it, though 2000 hours is a good guideline.

A worn stylus will damage your records faster than anything else, as the flattened areas of the stylus scrape away the vinyl from within the grooves. Though some refuse to believe that the hardest substance on earth can be defeated by a piece of soft plastic, the fact that diamond styli wear is not a myth and can be verified using an old stylus and a basic microscope. That is of course assuming that you can’t hear the difference, which is quite obvious. A worn stylus will produce splattering sounds when reproducing high frequencies, and may even cause visible physical damage to your vinyl such as white powder forming on the vinyl surface.

Cantilever Materials

The stylus cantilever itself is also made from 1 of several materials. Aluminium is the most common, with some more exotic cartridges featuring cantilevers made from Boron, Beryllium, carbon and expensive gemstones such as Ruby. While aluminium is the most common cantilever material in use today, low mass materials such as Boron are able to better trace the pattern inscribed in the groove wall, particularly in the high frequency ranges where the audio modulations are smallest and thus the stylus movement more rapid.

Some of the cheapest ceramic cartridges, usually those with Safire styli, use plastic cantilevers. Plastic is one of the worst possible materials to use in the construction of a stylus, and is reserved for the worst turntables money can buy.

The stylus tip is mounted to the cantilever in 1 of 2 ways. Bonding, in which the stylus tip is mounted to a mounting block and then glued to the cantilever, and nude mounting where the tip is glued directly to the cantilever. Nude mounting is the technologically superior method as the use of fewer materials results in lower overall mass of the stylus assembly. Many higher end cartridges however feature bonded cantilevers and in reality other aspects of the cartridges design will have a greater impact on the sound quality.

A few cartridges have been produced over the years with single-piece cantilevers, where the cantilever and stylus tip itself are cut from the same stone. This results in an extremely low mass assembly, and if properly manufactured results in a stylus tip that is in perfect alignment with the cantilever. Such an assembly is however expensive to produce and extremely fragile, requiring that the entire stylus assembly be replaced should the stylus become worn or chipped.

This article is part of our Guide to Turntables and Vinyl series. Continue reading: Part 3, A Guide to Phono Stages.