ART’s Pro VLA [Tape Op #37] has always occupied a funny little corner of the compressor world. It isn’t boutique, it has never been especially expensive, and it is not the sort of box that sends engineers down rabbit holes over its sonic lineage. And yet, in one form or another, the Pro VLA has remained in production for nearly three decades. It is unapologetically its own thing: the working engineer’s compressor. It does a useful job, does it musically, and has done it for considerably less money than many others on the market.
I still own my original, Rochester-built Pro VLA, and I still use it for a variety of tracking and bus duties. The original used a pair of 12AX7 tubes, Vactrol optical elements, and simple Fast or program-dependent Auto attack and release settings. Its successor, the Pro VLA II [Tape Op #74], expanded the options of the original by adding variable timing controls, revised metering, and some improved specifications. Although I never upgraded to the Pro VLA II, I have used those units and found the updates to mostly work quite well. The new Pro VLA III continues that evolution with further refinements and some new added features. ART claims increased headroom, lower background noise, and improved channel symmetry in linked stereo operation. The published maximum output has increased by 3 dB over the Pro VLA II, and the Solid State voice carries a much lower published distortion figure than the older model. Noise and dynamic range remain unchanged, according to the manuals.
At its core, the Pro VLA III remains a two-channel, soft-knee optical compressor that can operate as two independent mono channels or as a linked stereo pair. The most significant addition is the Voice switch; the optical gain-reduction stage remains in use either way, but the switch selects between a single 12AT7 tube gain stage or a solid-state stage. It would be easy to assume this is simply a “clean versus dirty” switch, but in practice I found that the two voices gave the compressor a much broader range of tonal usefulness yet still provided the familiar and forgiving behavior that made the older units so easy to use. If I had to characterize the difference, I would describe the Tube voice as something of a harshness-cutting “smootherizer,” while the Solid State voice brought some added clarity through the upper-mids and a bit of presence and openness on top.
The Ratio control now extends down to 1.25:1, compared with the 2:1 minimum of the previous models. Attack and Release remain variable. Link mode places Threshold, Ratio, Attack, Release, Bypass, and Master Output under the Channel 1 controls. Channel 2’s Output control then becomes a Balance control. In use, the lower ratio setting was quite useful, particularly when paired with the Solid State voice. This is especially impressive on a mix bus if, like me, you’re coming from the original Pro VLA unit. The familiar Pro VLA sound, which already had a nice clarity to it, can now produce even cleaner, more glued-together behavior, providing gentle gain reduction without leaning too heavily on the source.
Like the previous model, the front panel provides trimmable analog-output VU meters, separate LED gain-reduction meters, and a center LED input meter with average and peak-hold behavior. It’s a lot to take in, but it leaves little to question when in use. Also retained from the previous model are the detented potentiometers, a feature I wish were on my original unit! For anyone who recalls outboard settings from session notes or a phone photo, you know exactly what I mean. “Threshold at the twelfth click” is considerably more repeatable than “somewhere between ten and eleven o’clock.”