From K & K:
The Pre-Phase Preamp is a miniature, onboard preamp that provides volume control and a phase switch for Pure pickups. It provides truly astonishing sound quality in an extremely small and light-weight package!
The addition of the phase switch is one of the most important tools for live sound amplification of any acoustic instrument. Your unplugged acoustic guitar resonates in a given phase. The amplified sound needs to match this phase! Out of phase sound feeds back, has phase cancellations on some notes, and sounds quacky and tinny overall. Phase problems cannot be sufficiently solved with EQ. Any amp/PA/effect-unit/preamp may or may not flip the phase, the only way to be sure that your guitar is in phase with the amp-sound is a phase switch in your signal chain! In our opinion a phase switch is the #1 control for any amplified acoustic instrument.
The volume control wheel allows for convenient adjustment during performance. With the Pre-Phase you are able to plug your acoustic guitar into any amp or PA directly. Simply use the EQ on the amp or mixer channel to adjust your tone.
Battery life is about 150 hours with alkaline battery.
You can order the Pre-Phase as an integrated element with any single-source passive pickup, or as an Add-On for an existing pickup. Simply unscrew the existing endpin jack, remove it from the endpin hole, and plug it into the 1/4" plug of the Pre-Phase Add-On. The 1/4" plug has a self-adhesive fastener, which can be secured inside the guitar. The lightweight thumbwheel control mounts with a peel-and-stick installation to the inner edge of the sound hole. Mount the new endpin jack into the endpin hole, and you're done!