Let me preface this by saying that while I realize this unit falls more in the "budget" category, in my opionion the quality of this unit makes it worthy of a review here.
Introduction:
The ART VLA Pro II is an optical stereo tube compressor based on its predecessor, the VLA Pro. Improvements to the original include attack/release controls (the original VLA Pro had auto settings only), LED output level metering, and an enhanced link mode where the channel 1 level control acts as a master output and the channel 2 output becomes a pan control.
Fit and Finish:
Being made of mostly plastic, the VLA Pro II is lightweight for a 2U unit but the build quality appears to be quite decent. The prefab internals are simple and clean, consisting of a pair of chassis mounted PCB's connected by a pair of ribbon cables. The switches are of decent quality and the detented knobs are a very nice touch, making for easily repeatable settings and a more "professional" feel. Upon unpacking and racking, the unit was completely functional with no blemishes or defects, although I did need to recalibrate one of the VU meters (which was simple to do, since ART conveniently provides the means to access the calibration pots through the front panel).
The VLA Pro II uses a pair of 12at7 tubes in its gain stage, and I found the tubes shipped with the unit to be of much better quality than I expected from an off the shelf unit. After experimenting with different sets of tubes (JJ ECC83's, Philips JAN NOS 12at7's, and GT 12ax7's), I actually found that I preferred the sound of the EH 12at7's that came stock in the unit.
Application:
Tracking: The VLA Pro II is well suited to this purpose, being fairly transparent at even high compression settings. Turning the gain up increases the color of the unit, giving you a nice array of tonal options. The VLA Pro II became a quick favorite of mine for tracking bass as well as certain vocalists. The amount of dynamic control is wonderful; you can really flatten a source with virtually no detectable compression artifacts.
Vocals: My results varied the most here, and were strongly dependent on the source. On some vocals I was floored and on others I was less than impressed. For subtle compression duties the unit sounded great regardless of the source, but for really sqeezing a vocal and putting it up front in the mix the unit was hit or miss depending on the character of the vocalist's voice.
Bass: Very usable where a "warm and tubby" bass sound is called for. For a rock project I was working on it was exactly the sound I needed, but totally wrong for the metal project I worked on the following month. You can get more straight-forward tones by being a bit more moderate with the knobs, but if you're looking for something transparent for your bass tracks there are probably other tools that will get you closer to what you're looking for.
Electric guitars: This was my favorite application overall. I applied the unit to a wall of distorted metal guitars and was able to easily dial in the attack and release to exactly what I wanted. The guitars sat perfectly solid in the mix without losing their edginess and attack. A slight crank in the gain knob applied a smooth sheen to the tracks and added a bit more harmonic content. There was a definite "wow" factor here.
Drum bus: I was really able to exercise the attack/release controls in this application. The attack is quick enough to dial in a bit of pump or breath if desired, and the release curve is silky smooth; a long release time extended the decay of the cymbals in a very natural way. Sonically, I found that the unit really opened up the cymbals and top end nicely. Not to my own personal taste, as I favor darker units for drum bus duties, but I could definitely see the device excelling in this application.
Acoustic guitar: The VLA Pro II sounds wonderful on acoustic guitar. Again, you can dial the amount of compression from light to heavy, transparent to colored, as much or as little as you like. A bit of gain can add just the right touch of bottom and harmonic content.
Mix bus: Not only was the VLA Pro II usable on the mix bus, it actually sounded really, really good. Its transparent behavior makes it well suited to this duty and I really liked what it did to both the top and low end. A touch of gain can add some color, but be careful - a little goes a long way in this application.
Pros:
-Extremely flexible for just about any compression task.
-Excellent sound quality.
-At under $300 list (I purchased my unit new for about $250), possibly the best bang for the buck offering in the compression market.
Cons:
-I think ART went a little overboard with the LED's and VU meters. This thing looks like the Vegas strip during operation, with four LED bars and two VU meters flashing all over the place. The LED bars and VU meters also share much of the same functionality, making the need for both a bit redundant. ART could have easily gone with either meters OR LED's, using a three position switch to toggle between Input, Output, and GR. None of this effects the sound of course, and the lights aren't too bothersome as long as the unit isn't sitting right in front of you at mix position.
-You need to hit the input very gently with the VLA pro, as high input levels will cause the unit to distort in a very unpleasant way. The inputs are not transformer balanced, and ART appears to have implemented a TL072 in the input section of the device.
-Turning the attack knob to the fastest setting can do some pretty icky things to the transients of your source material. The unit is pretty fast for an opto, but not THAT fast.
Conclusion:
Everything I've seen of this unit so far leads me to believe that the VLA Pro series compressors are ART's attempt to deliver a "prosumer" version of the LA2A. In practice, I found the VLA Pro II to be VERY LA2A like, in both behavior and sonics (although less "dark" than an LA2A). A large part of the VLA Pro II's "flavor" lies in the gain knob, just as it does with an LA2A. The optical sensor "feels" very much like a T4B, but with the added bonus of attack/release controls.
That said, what the VLA Pro II doesn't have is the LA2A "transformer mojo", which is what many LA2A enthusiasts consider to be the heart and soul of an LA2A's character. But this also makes me think that the VLA Pro II may be a great candidate for DIY (I have an extra pair of HA100x's lying around that I'm considering adding to mine).
While certainly a professional quality device, the ART VLA Pro II probably isn't going to see much use in a studio stocked with original LA2A's, Purple's, Distressors, and other high end compressors. But for any studio owner or recording enthusiast on a budget the VLA Pro II is one of the most exciting and affordable units out there. Highly recommended.
-Lance