Musical instruments such as guitars and basses can produce only so much volume. To boost this level of volume and signal, musicians have to reply on amplifiers. Many of today’s combo amps are basically all-in-one models which consist of a speaker, preamplifier and power amp. These are typically smaller, relatively easy to carry around and highly versatile. This makes them ideal for practising and playing in small areas and why just about every guitar and bass player owns one. However, amps are also used for drum machines, keyboards and synthesizers.
The roots of the first amplifier systems can be traced back to the early 1900s. Early models consisted of vacuum tubes but transistors became more common in the 1960s. However, some models still use tubes. In general, tube-based amps provide a richer/warmer sound with a vintage steel and more distortion while solid-state/transistor models offer a crisper, clean sound.
Amplifier head units are also available and these are standalone components which are used in combination with external speakers. These are typically quite a bit more powerful than head units which are incorporated into a combo amplifier. The head unit consists of a preamp and power amp. With a standalone amp head you’ll also need speakers or a stack of them to boost the volume.
The size of the amplification equipment needed generally depends on how much power and volume is needed and this generally comes down to the size of the venue you’re performing in. For example, a huge amplifier or large speaker stack isn’t needed if you’re playing in a small, intimate setting or practising at home. On the other hand, if the amp is too small for a large venue then it will be hard for many listeners to hear you play.