The ART Pro VLA II is a Vactrol® compressor / leveler amplifier based on tubes and designed to excel in any professional audio environment. Superior performance and an incredible tone make the ProVLA II an indispensable tool for mixing, mastering, dynamic control of live sound sources, etc.Capable of delivering a natural sound and unmatched sonic compression in its class, the ProVLA II uses an optoelectronic circuit instead of the more typical VCA level detection circuit. This VCA-less design coupled with a 12AT7 tube in the gain stage makes the Pro-VLA II the ideal dynamic control device for critical audio applications.Signal integrity is exceptional with extremely low noise and low distortion, which is achieved in the ProVLA II through the use of a transformerless design in all its parts.Vactrol®Technology Unlike typical compression units that use voltage-controlled amplifiers (VCA), the Pro VLA II's optoelectronic design allows for much more transparent and musical sound compression without sounding aggressive or unnatural. This Vactrol-based optical electronic circuit is the basic component of classic vintage compressors.