If ever you want to build your own guitar amplifier, here’s the first thing you need to build. This is because guitar preamp are not usually sold as a kit unlike amplifiers. Guitar preamp are actually simple and usually consist of 2 stage, first – gain stage which amplifies the signal coming from the guitar and second – the filter stage which boost or cut frequencies that is determined by the user. Some preamp also includes effects such as distortion and reverb as the most common.