There are two distinct types of amplifier cabinets used in the design and manufacture of musical amplifiers: the combo or combination amplifier and the divorced or stack amplifier. An amplifier typically consists of two main components: the amplifier head and the speaker enclosure or cabinet. Amplifier cabinets often feature either closed back or open back designs. Another popular option that is used with amplifier cabinets is a semi-open or ported back design. Amplifiers are also classified as either solid state, also known as transistor amps, or tube amps.
Much of the tone and sound quality delivered by any amplifier is a product of the style of amplifier cabinets used. The combination amp incorporates a single cabinet to house both the amplifier head and the speaker or speakers. This design is popular with beginning guitarists and keyboard players, and is also used in a studio setting. Usually incorporating one or two speakers and a solid state power system, the combo amp is also commonly the least expensive choice in amplifier designs. The ease of portability and the quiet operation are two of the main reasons that players choose this style of cabinet.
Often used for live performances due to the increased volume and massive presence on stage, the divorced amplifier cabinet, or the stack as they are commonly called, uses a separate amplifier unit called the head to power the speaker cabinets or cabs. These amplifier cabinets are typically arranged in units known as half-stack and full-stack amplifiers. Half-stack amplifier cabinets employ a single speaker enclosure that consists of four speakers mounted in a square cabinet. The full stack includes the half stack and places a second speaker enclosure on top of it, which consists of four speakers mounted inside a slant-top cabinet. The top two speakers in the slant-top cab are pointed slightly higher than the other six to provide added volume to the farthest reaches of the venue.
Typically, the stack design provides the most volume and power of the two designs. Both of the designs commonly offer versions with closed cabinet backs as well as open backs. The closed-back design is used when added low-frequency sound is required, while the open-back amplifier cabinets claim to offer higher frequency sound. While the combo amps are typically solid state styles, the stacked amps are usually tube type amplifiers, however, solid state versions of the stack amp are also offered.
