Signal Processing
Pro VLA II
Two Channel Vactrol-based Compressor

The ProVLA II is a tube driven Vactrol®-based Compressor / Leveling amplifier designed to excel in any professional audio environment. Superior performance and an incredible tone makes the ProVLA II and indispensable tool for tracking, mixing, mastering, dynamic control of live sound sources or for use in broadcast audio.

Capable of delivering a far more musical natural sounding and sonically transparent compression than competitive units in its class, the ProVLA II uses an Opto-electronic circuit rather than the more typical design VCA driven level detection circuit. This VCA-less design coupled with a 12AT7 vacuum tube in the gain stage makes the Pro-VLA II the ideal dynamic control device for critical audio applications.

Exceptional signal integrity with extremely low noise and low distortion is achieved in the ProVLA II by utilizing a transformerless design throughout.

Vactrol® Technology
Unlike typical compression units that use Voltage Controlled Amplifiers (VCA's) to handle level detection, the Pro VLA II's Opto-electronic design allows a far more transparent and musical sounding compression without sounding aggressive or un-natural. This Vactrol based optical electronic circuitry is the basic component of the classic highly sought after compressors of past.

Vactrol® design allows the ProVLA II to react to audio signal in much the same way the eye naturally adjusts to fluctuations in light levels - smoothly, quietly and almost imperceptibly.

Soft Knee Leveling
The ProVLA II is a soft knee leveling amplifier by design. Although capable of providing dramatic compression effects, the ProVLA II was designed to excel in any application where transparent, expressively musical dynamics control is desired.

Comprehensive Metering
Large highly visible backlit analog VU meters accurately display input and output levels while extremely fast 10-segment LED's display gain reduction. For added functionality, the LED's display either average level for mastering & mixing applications or peak hold for monitoring individual sources when tracking audio.

Versatile I/O
XLR and 1/4-inch TRS balanced inputs and outputs are provided to ensure the ProVLA II can connect with any audio source or hardware. A +4dBu/-10dBu mode switch optimizes ProVLA II I/O for either consumer or professional equipment.

  • VCA-Less Vactrol Opto-Compression Design
  • Mastering Quality Audio Signal Path with Tube Gain Stage
  • Enhanced Link Mode - While in stereo link mode, channel 1 level control acts as a master output level and channel 2 becomes a balance control between them, - optimizing the Pro-VLA II for use as a mastering tool
  • Variable Threshold, Ratio & Output Controls
  • LED Backlit VU Input/Output Level Metering
  • LED Metering Indicates Both Average Level And Peak Hold
  • Accurate Ten Segment LED Gain Reduction Metering
  • +4dBu/-10dBu Mode Switch Optimizes Pro-VLA II For Interface with Professional OR Consumer Grade Components
  • Active Balanced XLR And ¼-Inch Inputs & Outputs
  • Toroidal Transformer Reduces Mechanical & Electrical Hum

Vactrol® is a registered trademark of Perkin Elmer Optoelectronics

Equivalent Input Noise @+4dBu: -99dBu (''A'' weighted) / @-10 dBV: -107dBu (''A'' weighted)
Maximum Attenuation 30dB
Input Impedance 10K Ohms
Maximum Input Level +20dBu (in +4dBu mode) / +10dBV (in -10dBV mode)
Maximum Output Level +20dB max
Frequency Response 10Hz to 100KHz (+/- 0.5dB)
Dynamic Range > 100dB (20-20KHz)
Attack Time 0.25msec. to 50msec. variable
Release Time Variable 150ms to 3s
Total Harmonic Distortion <0.1% (typical)
Slope Variable 2:1 to 20:1
Dimensions 3.5" x 19" x 9.2" (8.9cm x 48.3cm x 23.3cm)
Weight 10.5lbs (4.76kg)
Pro VLA II - Two Channel Vactrol-based Compressor
Pro VLA II - Two Channel Vactrol-based Compressor