So, you’re upgrading your cartridge? That’s one of several fine ways of improving the analogue listening experience. But it’s important to make sure your cartridge is compatible with your turntable. There are several things to take into account, but the very first one is: will it fit? And that depends on the type of mount the cartridge uses.
- There are two kinds of “mount” used to attach a cartridge to a turntable tone arm
- The Standard Mount (or 1/2-inch Mount) is by far the most common. You can identify it by the two round holes on the top, 12.7mm apart, which are used to fix the cartridge to the head shell of the tonearm
- The P-Mount is much rarer, and consists of a squarish plug on the end of the cartridge which fits in the end of a P-Mount turntable.
- Which you choose will depend entirely on the tonearm fitted to your turntable
- Some cartridges are available with your choice of mount, such as the Grado Prestige range.
Two types of mount
The cartridge “mount” is the way that the cartridge is attached to the turntable tonearm. For it to work well, it needs to be firmly attached, in the right position and at the right angle. There are two types of cartridge mounts for quality turntable equipment, plus one interesting variant we’ll deal with separately.
The Standard Mount (aka 1/2-inch Mount)
This is by far the most common cartridge mount, as the “Standard Mount” name suggests. And as the alterative name suggests, the two holes on the top are one half inch or 12.7mm apart. Suitable tone arms have two parallel slots, each about a centimetre long. You won’t be surprised to learn that they are 12.7mm – half an inch – apart. The standard mount cartridge is fitted to those slots. There’s usually room for fore-aft adjustment to allow the stylus overhang to be set correctly.
At the back of the cartridge are four signal pins, two for each channel. Four wires inside the tonearm are connected to these, one by one.
While I’ve said that the cartridge mounts to a tonearm, some tonearms use a detachable head-shell. That is, the part of the tonearm with the slots to which the cartridge is attached can itself be removed. Just about all detachable head shells use a scheme developed by Danish cartridge maker Ortofon and popularised by UK high-end tonearm maker SME. These head shells have a round shaft with four contacts on the end. They slide into a receptacle on the end of the tonearm, and a collar on the tonearm is tightened to hold the head shell securely in place. High-end tonearms tend to eschew removeable head shells because they add mass, complexity and additional electrical contacts. But they do have the advantage of allowing relatively easy switching of cartridges. For example, you may prefer to play mono LPs with a mono cartridge, or you may like to sometimes play 78s (which require a much thicker stylus).
The P-Mount or T4P
This is the other main kind of cartridge mount. I hesitate to call it common because, after following audio for several decades I had been unaware of it until very recently. It turns out it was introduced in around 1980, in part for convenience and in part to work better with linear tracking turntables.
P-mount turntables have a square-section shank with fits into the end of P-Mount tonearm. A screw is inserted into the side of the tonearm through the shank to ensure it stays in place.
As with Standard Mount cartridges, at the back of the cartridge are four connection pins. However these mate with a connector in the shaft of the tonearm. They are somewhat thinner than the connection pins on a Standard Mount cartridge.
How to mount a P-Mount cartridge, from the manual of an old Technics turntable
All P-mount cartridges have the same major dimensions, particularly from the rear to the stylus, along with the relative stylus height. All tonearms which are designed for P-Mount cartridges are designed around those dimensions. That makes installation of P-Mount cartridges extremely easy since there’s no fiddling around with cartridge alignment. Just install and then balance the tonearm.
P-Mount cartridges are more common with linear tracking turntables. These are very rare. Instead of using a tonearm on a pivot, the arm is mounted on a rail so that the whole arm slides evenly towards the middle, with the cartridge remaining at a tangent to the groove at all points, instead of varying by several degrees.
Because P-Mount cartridges are all physically compatible with each other, there are adaptors available which you can use to make a P-Mount cartridge work with a Standard Mount. There seems little point in buying a new P-Mount cartridge simply to use it with a standard turntable. However this can be a useful solution for those with a much-loved P-Mount cartridge that they wish to continue using in the absence of a compatible turntable.
A confusing variant
Finally, at least one brand offers several cartridges that are designed to fit a tonearm with a detachable head shell. They have a round shank, just like the head shell, and can be fitted straight into the receptacle on the tonearm. These will be mostly seen in DJ-style turntables. The lack of a head shell and the pointed design of these cartridges allow a DJ to place the stylus into a groove with greater precision.
But remember, DJ cartridges are optimised for greater robustness – they do have to cope with records being rotated the wrong way – and typically employ heavier tracking pressures. With high fidelity cartridges, the design imperatives are elsewhere directed.
I could say: “If in doubt, use the Standard Mount”. But there’s never any reason for doubt. If the tonearm to which you intend to attach a cartridge has those two slots on the top half an inch apart, you’ll know you want Standard Mount. And that will be the case for more than ninety nine percent of quality tonearms.