The Pure Mini is a transducer-only system. No battery, no onboard electronics, just the pure pickups. Don't be fooled by the sound of some competitors' "thin sounding" passive systems. The Pure Systems are definitely different. They sound full and rich and have sufficient output to drive most amps and PA systems directly, without a preamp! Advantages of the Pure Guitar System The special Pure surface transducers transmit a significant portion of the soundboard because they are not as close to the strings as an under-saddle pickup. Each of the 3 transducers is designed to pick up a specific string pair, but also "listens" to the adjacent area around the bridge. The Pure pickups are not under pressure and therefore do NOT sound percussive or harsh. The Pure System reproduces all strings nicely balanced, a known problem with under-saddle pickups. The Pure System sounds great just in passive mode! Unlike under-saddle pickups which passively can sound thin and trebley, the passive PURE system puts out a nicely balanced, warm, full range signal. Feedback Resistance How safe is the Pure System with feedback? Due to the Pure System's location on the bridge plate under the bridge, feedback resistance is comparable to under-saddle transducers. Technically, a pickup installed in or on the bridge is a lot less likely to feedback than one which is attached to the open sound board. The 1/8" thin sound board can act like a diaphragm and vibrate along with loud sound-signals from speaker cabinets. This is the kind of feedback you experience on an acoustic guitar. The thicker bridge area is a lot harder to be set into vibration from an outside source simply because of its mass. In our tests with both, steel string and classic guitars equipped with an under-saddle pickup plus the Pure System, we were able to achieve about the same gain-before-feedback with both systems.