Acoustic Guitar Pickups
At first glance, the idea of pickups for an acoustic guitar may sound a little off. After all, the whole point of an acoustic guitar is that it doesn't rely on pickups and amplifiers. However, sometimes you want the sound of an acoustic guitar but you need to fill a space that's too large for the un-amplified instrument on its own. That's where electro-acoustic guitars come in, combining acoustic sound with electronic amplification. All you need to do is add pickups.Undersaddle Pickups
Perhaps the simplest pickup option is to go with undersaddle pickups. Based around a set of piezoelectric crystals, these pickups are not very exy and are extremely reliable. The crystals mount under the bridge, one for each string, and create a current from the vibrations. They are entirely passive, but produce weak signals so you usually have to mount a preamp inside your instrument. This is usually a permanent installation.Magnetic Pickups
Another way to do it is by installing magnetic pickups into the soundhole. The good thing about this approach is that you can add them for one performance and remove them for the next without affecting the integrity of your guitar. They pickup string vibrations just like an electric guitar, and send them on to the amplifier. The one drawback is that some people find they sound too much like an electric guitar.Contact Pickups
Another under the bridge option is to go with contact pickups. The big advantage here is that they are able to pick up both the string vibration and the top vibration of the instrument, so they retain the acoustic sound. You can get feedback at higher volume, but they work very well for anyone seeking top sound fidelity.Blended Options
Blended options add a microphone to one of the existing pickup types. This gives a greater accuracy of sound and offers more flexibility as you can often choose either or both inputs depending on the situation.