A combo guitar amplifier includes all amplifier components in a single enclosure. Unlike separate "stack" amplifiers, where the amplifier and speaker cabinet are individual units, a combo amp is self-contained and designed for portability. Combos come in sizes, configurations and power levels to suit every need, and are popular with beginners and professionals alike.
The benefits of combo guitar amplifiers are portability, ease of use and--on some models--expandability. No separate connection of the amplifier and speaker is necessary for normal use, but some combos can be attached to larger external speaker cabinets or additional amplifiers, if desired. Depending on the make and model, combo amplifiers have all the power and features of stacked amplifiers, but with fewer speakers.
While combo guitar amps offer many benefits, their only limitation is the number of built-in speakers. With few exceptions, combo amps come with one speaker for lower-powered models, and two for higher-powered models. In comparison, half-stack amplifiers typically use four speakers, while full-stacks use eight. The advantage to having more speakers is better sound coverage in larger performance venues. But since many combo amps allow the attachment of additional speakers, the choice between a stack or combo comes down to personal preference.
Tube Combo Amps
Tubes, originally used in the first guitar amplifiers, are still popular today. There are numerous tube combo amplifiers on the market, but they tend to be more expensive than solid-state units. Tube amplifiers are known for their distinct sound, but they are subject to periodic maintenance, and tube replacement can be expensive. Some combo amplifiers use "hybrid" technology, where a tube is placed in the preamplifier circuit to produce a tube sound, with the power amplifier is solid-state. Hybrids offer the sound of tubes with the reliability of solid-state.
Solid-state Combo Amps
Solid-state combo amplifiers are a popular and cost-effective alternative to tube amps, especially for smaller practice or studio combos. Solid-state amplifiers require no maintenance, and there are no tubes to replace. Although the "tube versus solid-state sound" has been debated for many years, again, it is a matter of preference. Solid-state amps are known for providing reliable performance and for producing a "cleaner" guitar sound at high volumes than tube amps.
Modeling Combo Amps
Modeling combo amps use tube, solid-state or hybrid circuitry, and include digital processors to emulate the sounds of different amplifiers and effects. These amplifiers allow you to dial-in numerous preset sounds, and some include the option of creating your own sounds in addition to the presets. Modeling technology was once very expensive, but is now available on many entry-level combo amps.