Choosing an Acoustic Guitar Pickup
I often get asked the difference between the common guitar pickups on the market, it's very hard to choose between the types.
Hopefully this article will help you weigh up your options!
Types of acoustic guitar pickup
Undersaddle Pickups
These pickups work living under your bridge saddle, the piezo element works on the pressure change as you pluck a string. A small hole is drilled in the saddle slot for the cable. There are many types around, some have a small preamp which is connected directly to a jack socket/strap pin unit.
Some are available as "passive" and don't require a battery.




Fishman Matrix Infinity Artec EPP-PZ system B-Band 22 R pickup Highlander iP-1
Pros - helps to reduce feedback
Cons - the piezo unit under the saddle affects the coupling between the saddle and the guitar top
Contact pickups
This type of pickup is glued to either the bridge plate or the soundboard inside your guitar. Because this type of pickup is listening to the sound board, the guitar is susceptible to picking up tapping on the body. Often these systems also use Piezo elements.
They're great at providing an even string balance and sometime its a good option for instruments with a weird saddle slot.



K&K Pure Mini LR baggs IBeam B Band AST 1740
Pros - balanced string to string output
Cons - will pickup tapping on the body and finger noise
Soundhole Pickups
These pickups suspend directly over the soundhole, it's possible to uninstall these relatively easy leaving no permanent marks. There are some models available where you trail the cable out of the sound hole to your amp so you don't even need to install a jack socket.
They work on sensing the magnetic properties or your strings, similar to electric guitar pickups.




Seymour Duncan Woody Artec WSH12 Fishman Rare Earth LR Baggs M1 Active
Pros - minimal modification to the guitar itself
Cons - different tone, visible, no use on nylon string guitars
Multi Source Pickups
Right, these pickup systems are the most complicated as they blend together 2 or more sound sources. I have seen ones which blend a microphone, an under saddle pickup and a magnetic sound hold pickup all in one.
While they have the most options for tailoring your sound they often need a control panel installing.



Fishman rare earth blend LR Baggs Anthem SL Highlander iP-2 Dual System
Pros versatile sound properties
Cons - pricey, often bulky and most commonly misunderstood by the user!
Internal Microphones
Microphones inside guitars tend to give a nice natural sound however they are very prone to feedback. Many players use these in recording and less so when on stage or in loud environments. You often see them as part of a blend system so that they can be turned down and let the piezo take over for live use.



LR Baggs Anthem Highlander Internal Microphone GHS acoustic soundhole microphone
Pros nice tone reproduction
Cons - big on screeching feedback
Endpin Jacks
Endpin jacks are a great way of combining your strap pin and jack socket into one. They're very discrete!
Preamps
Preamps offer advantages when it come to sound shaping, some have controls and some are preset. The ones with controls often need a control box mounting onto the guitar. I can install these no problem, you just have to be sure that you want it as installing preamp boxes is very intrusive and permanent!
The upside is that you can get a variety of gadgets which are included like tuners, feedback suppressors, phase controls, EQ controls or even USB ports built in!
Batteries 
Batteries can be annoying, you need somewhere to mount the battery whether it be inside the guitar or mounted to the outside face. Don't forget that you will need to keep a spare inside your guitar case as the battery will only run out on stage in front of large crowds.
I hope that this page has helped you make a decision to choosing a pickup for you guitar. I can install and supply all the pickup systems listed here and more, the ones on this page are ones that I recommend.
-Jack