K&K Double Helix Upgrade System

K&K Double Helix Upgrade System, in addition to the Pure Pickup, comes with one K&K Double Helix soundhole pickup, hum-cancelling dual-coil pickup for steel-string acoustic guitars, it features a phase switch and a unique tone switch that allows players to easily change from a bright GLOSS setting to a more substantial STEAM setting, K&K Dual Channel Pro Preamp ST preamp, compatible with both piezo and magnetic pickups, one stereo input, two outputs, a main/mix out and an individual channel output, internal 3-band EQ for both channels, 2 x volume control, frequency range 10 - 30,000 Hz, input Impedance: 1 Mega Ohms, output Impedance: 3 K Ohms, average current: 3.5 mA.