Roll Music VacbaxThe Roll Music VacBax 500 is an all tube single channel 500 Series two band baxandall EQ. The Roll Music VacBax 500 uses a passive design and boasts a fixed 150Hz Bass frequency and offers a choice of two frequencies (8kHz or 16kHz) for the high band. In addition, it includes a switchable 100Hz hi pass filter. The VacBax 500 uses Roll Musics proprietary high voltage internal voltage booster which delivers 200V internally from the + 16V and +48V rails