PowerTube

The PowerTube is a 500-series module that places a 12AX7 vacuum tube in a class-A signal path. An internal non-radiating charge pump raises the tube's supply to 140 volts, which gives the stage the headroom and character associated with high-voltage tube amplifiers. The tube feeds a class-A balanced output stage, and the combined gain reaches 60dB, enough for most microphones.

The input is transformer-coupled with a Jensen transformer, and the electronics are hand-selected, fully discrete class-A parts. An Air switch adds a slight edge to vocals or sparkle to acoustic guitar, while a high-pass filter reduces low-frequency resonance.

The module is a single-width design, and its powering scheme lets eight units run in a Workhorse power rack without losing dynamic range. This suits multi-channel live recording. It can also be placed after an instrument input such as the Omniport on a Workhorse, Cube or PowerStrip for bass, and be followed by a compressor or amp simulator.