There are many different types of guitar amps on the market today from the combo amp to the full stack. You also have a choice from a all tube amp to a hybrid design. Below we included the descriptions of each amp type.
Combo Amplifiers - Combo amps are named because they combine the amplifier and speakers into one cabinet. They are convenient to set up because no additional speakers need to be connected before the amp can be used. Also, the speaker cabinet design usually is well matched, since they are designed as a single unit.
Head and Cabinet Amplifiers - In this configuration, the amplifier is separate from the speaker cabinet. The head usually sits on top of the speaker cabinet. Usually, these are fairly high powered systems designed for concert hall use. Separating the components of the amplifier allows selecting and matching the speaker cabinet to the head Also, these speaker cabinets are often very large. Combining the amplifier with the speakers would make for one HUGE amp, which is not convenient for those of us who don't travel with forklifts. A head combined with a cabinet containing 4, twelve inch speakers is often called a "half stack." Two of these cabinets make a "full Stack."
Rack Systems - This configuration allows the player to individually select every component in the amplifier system. A separate component serves each function of a typical combo amplifier. The rack system consists of a preamp, power amp, effects/signal processors and the speakers. The individual components are mounted into a cabinet designed to accommodate the standard sizing of these pieces called a rack which is 19". For many players, the rack system provides flexibility not available with the other configurations.
Mini Amps - Mini amps also known as small practice amps are like small combo amps in design where the speaker and electonics are combined in one unit. Mini Amps are great for the traveling guitarist, since you can use batteries to operate them and their small in size.
Solid State Amplifiers - This is the circuitry most commonly used in modern amp designs. Typically, they are affordably priced and quite reliable. They use transistors to deliver the output to power the speakers instead of tubes. Solid state amplifiers are available in both combo and head configurations.
Tube (valve) Amplifiers - Tube amps use glass vacuum tubes to shape the tone and deliver the output power to the speakers. Tube amps are typically associated with a warmer, more complex tone than solid state amplifiers. The tradeoff is a higher price tag, maintenance issues (like tube replacement) and, since the tubes are made of glass, these amps can not be abused then expected to work properly when you get to the gig. However; most serious players agree that for pure tone and feel, tube amps are the way to go.
Hybrid Amplifiers - These amps are designed to bridge the gap between solid state and tube amplifiers. Their preamp section uses one or more tubes (usually 12AX7) to shape the tone. Transistors take over to deliver the power to the speakers.