Understanding the Vinyl Record Stylus

There is more to the stylus used for vinyl records than meets the eye, and it certainly should not be called a vinyl needle as it is finely honed for transcribing the vibrations in the grooves.

Vinyl Record Player Technology Includes:
Vinyl technology - the basics     Turntable     Pickup arm / tonearm     Pickup cartridge     Stylus technology    

Although the term stylus is often used interchangeably with the overall pick-up cartridge when discussing vinyl record equipment and technology, the actual stylus is the small tip of the cartridge cantilever than is in contact with the record grooves.

This small stylus must stay in contact with the groove despite the enormous forces exerted upon it to ensure the faithful reproduction of the sounds contained within the grooves.

Close-up of a vinyl record cartridge stylus

Vinyl record styli vs needles

Although people often refer to the styli used in modern vinyl record players, they are not needles, but finely manufactured styli.

The term needle is more correctly used to describe the steel needles used with the old gramophones that were in use prior to the invention of the modern vinyl record player.

The needles were made of hard wearing steel, and they also had much larger dimensions and therefore they are totally unsuitable for the modern vinyl records.

It is still possible to obtain the old needles for 78 wind-up gramophones, but it is necessary to go to specialist vintage gramophone dealers for these.

Modern vinyl record styli basics

Modern styli used for modern pickups are generally made from diamond to provide the required level of hardness to reduce wear and provide a long and useful lifetime.

Considering the enormous forces applied to the stylus, an incredibly hard wearing material is required for this.

Close-up of a vinyl record cartridge stylus

It is important that any stylus used is not unduly worn, otherwise damage can result to the vinyl record. A correctly set up system and little worn stylus will not rapidly degrade the record groove, so it is always best to replace the stylus before any undue wear occurs.

As the cost of diamond is obviously relatively high there are a number of approaches that are used:

  • Use of diamond only stylus:   The best option is to use what is sometimes referred to as a "nude" stylus, because it uses only diamond int he stylus. This gives the best transmission of the vibrations to the actual transducer via the cantilever. However it is also the most expensive. However, with industrially made diamond, the costs may not be as high as might have previously been expected.

  • Composite stylus:   Some of the lower end cartridges and their styli may be a composite construction having a diamond tip, but another hard material to interface the stylus tip to the cantilever.

  • Sapphire:   Another alternative, which is less used these days is to use a sapphire stylus instead of diamond. Although very hard, the sapphire wears more quickly and will obviously need replacement more often. The economics of this may be dubious these days.

the profile of the stylus is also very important. There are several types of stylus profile that are used. Each type brings its advantages and disadvantages, so it is worth understanding what each type is.

  • Spherical:   Spherical styli are bar far the most commonly used type of styli and they are most basic profile. This type of stylus has a conical shape and the sip is spherical with a radius of around 0.6 to 0.7 mil, i.e. 15 - 18 microns.

    They are lower cost because they are easier to manufacture, but they pick up less information from the record wall and also they place higher levels of pressure on localised parts of the groove. Essentially the contact area for the stylus is about half way up the groove and also its contact span is too large to pick up the shorter wavelengths, i.e. those for the higher frequencies.

    The maximum frequencies will depend upon the position on the disc - as the inner of the disc has a smaller circumference fort he groove, the maximum frequency will be less that at the outer reaches of the disc where the groove circumference is much greater. This translates to a maximum frequency of just under 10kHz for the inner and 48kHz for the outer areas of the disc for a typical elliptical stylus.

  • Elliptical:   Elliptical styli have their sides polished so they read more of the groove, but are still at the more affordable end of the price spectrum.

    The major radius if the elliptical stylus sits across the groove so that it maintains the correct position in the groove, but having the shorter radius in the direction of the groove, it can correctly track the shorter wavelengths, i.e. higher frequencies much more accurately.

    Using a typical elliptical stylus, the maximum frequencies for the inner of the disc tend to be around 11 kHz. Also the distortion levels are less because the elliptical stylus matches that of the cutting stylus for the original master disc much more accurately. Even so, distortion levels of around 4% at 8 kHz may be experienced at some points.

  • Shibata styli:   These styli use a parabola instead of a cone shape. This achieves a contact area of four times that of the spherical stylus. This improves tracking, it reduces wear and also doubles the stylus resonant frequency.

There is a lot more to the technology behind the stylus used for vinyl records than might be thought at first glance. Understanding the physics and general technology behind them enables a better understanding of the performance to be obtained.

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