What is a phono cartridge?

Think of it as a mechanical microphone. As a microphone converts air pressure changes into a corresponding voltage, a phono cartridge converts the mechanical topography of a record groove into a corresponding voltage. How does it do it? To begin, let’s look at the anatomy of a phono cartridge from the vinyl up. Given the general simplicity and relatively few parts that comprise a phono cartridge (and the precision with which it must execute its job), each component plays a significant role in the success of a design. No single component is fully isolated from the others, and any deficiency in one will adversely affect the task of the others.

Stylus – The material that contacts the record surface. Its mass and shape are instrumental in its ability to accurately trace the specific type of groove cut into the record surface. The goal is for the stylus to hold the groove despite mechanical conflict between it and the record surface.

Cantilever – A rod or tube that connects the stylus to the generator of the cartridge.

Suspension – An elastic device (typically a variety of rubber) that secures the cantilever firmly in position yet allows it to remain compliant enough to allow it to move as the stylus does.

Suspension Wire (MC cartridges only) – On the generator end, a wire is attached to the cantilever that can be pulled to create a tension of the coil assembly against the suspension elastomer. This tension defines the behavior of the suspension in relation to the mass and tracking force of the cartridge. It is a critical adjustment when building the cartridge.

Generator – The part of the cartridge that converts stylus movement into voltage. There are many different types of generators. We will focus on what Sumiko offers, which are moving magnet and moving coil designs. The amount of movement in either the coils or the magnets is miniscule. To achieve uniform voltage output from all angles of movement as directed by the stylus, the tolerance and positioning of the various components that make up the generator must be very precise.

Cartridge Body (mounting structure) – The assembly that houses the generator and provides the attachment method of the generator to the tonearm.