Mechanical device and Tone arm

Mechanical device noun - Mechanism consisting of a device that works on mechanical principles.

Tone arm and mechanical device are semantically related. In some cases you can replace phrase "Tone arm" with "Mechanical device", this phrases are similar.

Tone arm noun - Mechanical device consisting of a light balanced arm that carries the cartridge.

Mechanical device and tone arm are semantically related. You can use "Mechanical device" instead a noun phrase "Tone arm".