The Joyo JE-306 is an acoustic guitar pickup system with a built-in preamp, designed to amplify the sound of an acoustic guitar for live performances or recording without relying on external microphones. Here are the key features of this device:

1. Pickup Type: The Joyo JE-306 is typically a piezo pickup system that can be easily attached to an acoustic guitar. Piezo pickups are popular for acoustic instruments because they capture the natural sound from the vibration of the guitar body.

2. Built-in Preamp: The unit comes with an integrated preamplifier (preamp), which amplifies the signal from the pickup before sending it to an amp or PA system. This ensures a stronger, clearer signal, reducing noise and interference.

3. Control Options: Many acoustic pickups like the JE-306 include simple controls for volume, tone, and sometimes even equalization (EQ), allowing you to adjust the sound directly on the guitar without needing external gear.

4. Ease of Installation: The JE-306 can be easily mounted on the soundhole of the guitar, which makes it a non-invasive option compared to some pickup systems that require drilling or permanent modifications to the guitar.

5. Battery-Powered: The preamp requires a small battery (often a 9V battery) to operate, providing enough power to boost the signal.

This system is particularly useful for players who want a plug-and-play solution for amplifying their acoustic guitar with minimal setup. It's ideal for live performances, especially in situations where feedback control is crucial or where the player needs to maintain the natural acoustic sound without relying on stage microphones.