12AU7 Preamp

The Hagerman Amplification 12AU7 Preamp is an all-analog vacuum-tube preamp designed primarily for acoustic guitars and piezo pickups. A JFET input stage provides a high 5 MΩ input impedance to preserve low-frequency response when connected directly to piezo pickups, while the 12AU7 tube adds warmth to the signal. Its tone controls provide adjustment for a more natural amplified acoustic response. A galvanically isolated XLR output allows direct connection to a PA system, with a side-mounted ground-lift switch to help reduce hum and buzz. The preamp can also be used with bass and synthesizers. It provides up to 15 dB of gain, a 50 Hz–20 kHz bandwidth and 2.5% distortion at 500 mV.