Review: UAD AKG BX 20

The AKG BX 20 spring reverb made its first appearance in the late 1960s and quickly became a favourite among studios worldwide. The lush sound of this complicated German combination of mechanical and electronic technologies all housed in a unique wooden box has graced countless tracks since, and has now been digitally emulated for UAD Powered plug-in users.

The original BX 20 was a dual mono device but the UAD BX 20 plug-in has expanded its options with a slightly unusual mono/stereo matrix that can either run with the original Tank A and B topology, an A+B setting that cascades the two channels together, or in new ‘stereoised’ modes for tank A and B as well as linking the two channels’ controls for more balanced A+B stereo use. There are a simple range of controls on both channels including treble and bass EQ (borrowed from the earlier BX 10 model), continuously variable pre-delay and wet/dry as well as buttons for direct mute, wet solo and low frequency roll-off. After much searching for the perfect specimen, UA chose producer Jon Brion’s original AKG unit to emulate.

The sound of the BX 20 plug-in can best be described as lush, dark but detailed with a retro character to it. It has none of the ‘ping’ and boxiness that you may associate with the sound of some other spring reverbs. There’s a quality to the BX 20 that really draws you in, and I noticed that unlike some other reverbs where you hit a definite ‘that’s too much’ threshold, this one offers valid effects at quite an extended range from subtle to extreme. There’s some beautiful evolving detail in the tails on sparser material and, despite the limited set of modifiers, it offers quite a lot of control over how the sound responds to musical instruments in different contexts.

The BX 20 has a strong ‘voice’ in more spacious arrangements and adds nice low mid timbre to vocals and other instruments where it can act as an extension to the body of the sound. It works beautifully on guitars and percussive instruments and I was able to totally transform a fairly dry existing mix into a 100% valid new ‘wet’ version with tons of BX 20 on just about everything; it’s great on kick and snare, bass and electrics.

With a maximum time factor of 4.5s and a minimum of 2s, the BX 20 is far from being the most flexible reverb around. Two seconds is, sadly, a fair bit too long for more subtle ‘body building’ short reverb techniques that can add invisible weight to vocals and guitars, although a touch of the BX 20 can work on drums in this manner. As a final experiment I tried inserting it across a whole mix on a faster rock track by Melbourne band Canary. With the pre delay set to zero, minimum bass and maximum treble EQ, the low cut engaged and the dry/wet balance set to about 30% (it’s a bit hard to tell with the sparse legending) the track took on an expansive, sparkling texture without sounding too hollow or wet. Again this was a surprisingly useable sound and another sign of a quality reverb.

Up against my previous favourite UAD reverbs, the EMT 140 and the Lexicon 224, the BX 20 holds its own and will be first choice in some contexts from now on. It’s a positive point that it doesn’t really sound like the others and does its own ‘thing’, meaning those who buy this plug-in will find new creative options waiting for them. Of course, you can use the 14-day plug-in trial period to really suss out whether it floats your reverb boat.