Basics

Preamp/Poweramp

The are two parts of an amp that the guitar signal travels through before it arrives at the speakers. The first part is the preamplifier where things like the amount of overdrive is generated. The second stage is the power amplifier which is where the signal is amplified. There is also an EQ stage in amplification which is usually within the preamp section.

How Many Channels?

Most amps have two channels. Channel one is for clean sounds and channel two is for Overdrive. The channels can be switched via foot pedal which allows guitarist to change between clean sounds to overdriven sounds when playing live. Some amps can also have 3 or even 4 channels which creates a wide range of versatility in an amplifier.

Effects Loop

If a guitarist wants too use effects such as stomp boxes with their amp they’ll need to use the amps effects loop. The most important part off the effects loop is where it is placed in the amps signal. This is after the preamp stage and where the overdrive sounds are generated and before the power amp stage where the overall signal is amplified. Having said that certain effect pedals such as overdrive, wah wah, and compresson are best placed in the input stage of the amp. Modulation effects such as delay, chorus, flanger and phaser are best routed via the effect loop.

Combo or Stack?

A combo is a ‘combination’ of the preamp/power amp and all controls with the speaker contained in one unit, hence the name ‘combo’. This makes things much more convenient and easier to transport compared to the other amp type which is called a ‘Stack’. The stack system requires a ‘Head’ which houses the preamp/power amp and all other controls. This is connected with speaker cables to a wooden speaker cabinet, otherwise known as a ’cab’. There are two types of ‘stack’ a half ‘stack’ which has one speaker cab and a full ‘stack’ which has two ‘cab’s’. Two of the most common cabinet sizes are 2×4’s which have 2 speakers that are 12” and 4×4 which have 4 speakers that are 12”.