Electric banjos are becoming more and more popular as players are using the banjo in many different genres and playing on bigger stages in bands that feature electric guitars, drums, and other loud instruments. Trying to use a microphone to amplify a banjo in these instances can prove to be very frustrating as a banjo will tend to cause the microphone to feedback when the volume is turned up loud enough to be heard both on stage and out in the audience.
In the late 1980's, Deering invented the electric Crossfire banjo to solve this problem. This banjo was used by Bela Fleck when the Flecktones were together. Bela had also modified his Deering Crossfire banjo with an additional MIDI pickup which allowed him to create all sorts of sounds on his banjo. The problem with the Crossfire was that it caused the banjo player to purchase an additional banjo for playing with loud bands and for acoustic situations to use a traditional banjo.
Banjo pickups were on the market, but they didn't work very well. They sounded generally pretty bad and they would still feedback quite a bit when turned up loud enough to compete with loud electric guitars and drums. Some of these traditional pickups for banjos were piezo and Fishman pickups. You could turn your banjo into an acoustic / electric banjo, but the electric part didn't really work.
Finally the Kavanjo pickup came out on the market about 5 years ago. This pickup, which is handmade by pickup master John Kavanaugh in Salt Lake City, Utah solved these problems. The Kavanjo pickup is esentially a humbucker pickup that would be used for an electric guitar, on the underside of the head of the banjo. It is sold premounted to a head so all you have to do to install it is change your banjo head.
This banjo pickup has been quickly picked up as the banjo pickup to use, with artists such as Mumford & Sons, Taylor Swift, Dropkick Murphys, and many more using this pickup.
You might think that a pickup like this might sound too "electric" sounding, and not acoustic sounding enough but the handwinding of the pickup that John Kavanaugh does and the way it mounts to the head really brings more acoustic qualities out of your banjo than you would think.
The only trick to the instalation can be in how to mount the output jack. To solve this probelm there are a number of options available for the jack. The most common and easiest would be to purchase the Kavanjo pickup with the jack premounted to the head. For openback banjos there is an option available where the jack mounts to the coordinator rods or dowel stick via velcro straps. The most complicated option is to mount the jack through the rim, and for resonator banjos to then put the jack on the flange. This last option can be tricky due to the different type of flange designs and resonator sidewalls. You might have to carve out a bit of the resonator sidewall with a Dremel and/or drill a hole or expand a hole in the flange.