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.”
Putting the unit through its paces, I started with bass, where the Tube option made sense. The bass track popped forward in the mix, but not because the unit simply made it louder or brighter. It brought a more present quality while keeping the pick attack on the strings from jumping out ahead of the body of the note. This is exactly the sort of sound I associate with a good optical compressor, where it smooths and levels a take without sacrificing too much of the player’s pick dynamics. Bypassing the Pro VLA III did not produce a dramatic, special-effect moment, but the bass just seemed to step backward and become less finished sounding.
Mixing electric guitars demonstrated that the Voice switch is more than just a novelty. In Tube mode, the guitars stayed mid-present and substantial, with a pleasantly dialed-back top end and presenting upper frequencies that were rounded rather than dulled. It didn’t take long to get a thicker, more saturated sound that worked particularly well for rhythm tracks. Switching to Solid State brought more clarity through the mids and high end. I found this especially useful when a guitar track needed to pop out and occupy its own space without my EQ'ing away a tone I already liked. In practice, neither Voice setting made the other obsolete; in fact, each offered a genuinely useful and distinctly different way to fit a guitar into a mix. Moving beyond individual guitar tracks, I tried the Pro VLA III on stereo guitar sources heavy with modulation, delay, and reverb. As mentioned, when linked, Channel 1’s Output control becomes the master level, while Channel 2’s Output control becomes a balance trim. This feature made it easy to lightly compress and at the same time recenter a slightly right-side heavy, uneven image then level-match the processed and bypassed signals without grossly upsetting the stereo relationship between the two channels. It’s a smart feature that is not present on my original unit, having been introduced on the Pro VLA II. I found it particularly useful on stereo guitar tracks and buses.
In processing vocals, I used the Pro VLA III in dual-mono mode as a two-stage dynamics chain. Channel 1 handled primary compression in the Tube voice. I sent its output into Channel 2 in Solid State and set it more aggressively as a limiter. Here again, the versatility of the Voice switch proved useful, as did the expanded Ratio range. The result was a well-balanced vocal that stayed firmly in place without obvious pumping or flattened phrasing. Peaks remained under control, but the performance never sounded clamped down, and cascading both channels introduced no appreciable increase in the audible noise floor.
There are many praises to be sung about this unit, but I feel that a few additions would have given the Pro VLA III an even higher performance-to-value ratio. A sidechain high-pass filter would make the Pro VLA III much more flexible across full mixes, bass-heavy drum buses, or anywhere low frequencies can pull the detector around. Also, a wet/dry mix blend control would improve and simplify parallel compression without the hassle of additional routing. These are small grievances and ones I realize would potentially place the price point of the unit in a slightly higher tier. Neither omission prevented me from getting very useful results!
In the end, what mattered most to me was that the compressor still behaved like the Pro VLA I know while covering more ground sonically than either of the earlier versions. Despite the feature updates made to the series, the compressor still encourages you to listen rather than spend the session navigating controls. That, I think, is one of the Pro VLA III’s greatest strengths: it does its job with aplomb yet rarely calls attention to itself. It is exactly the type of compressor the series has become known for, in that you may not always be sure it’s there, but you certainly miss it when it isn’t. For anyone who wants an affordable stereo optical compressor that can move between gentle leveling, tonal shaping, and practical peak control, the Pro VLA III remains easy to recommend.