AKG® BX 20 Spring Reverb

AKG® BX 20 Spring Reverb


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The only AKG-licensed emulation of this one-of-a-kind spring reverb.

Introduced in the late 1960s, the AKG BX 20 reverb was a high-water mark for AKG’s esteemed engineers. An ingenious assembly of mechanical and electronic componentry, the BX 20 offered the glorious depth and color of spring reverb without any of the limitations.

The AKG BX 20 Spring Reverb plug-in for UAD-2 hardware and Apollo interfaces is exclusively endorsed by AKG Acoustics, Austria and envelops your sources in gorgeously dark, dense ambience that only spring reverb can provide.

Now You Can:

Mix with the only licensed and endorsed AKG Acoustics BX 20 reverb plug-in

Envelop instruments in dark, dense, clear ambience with original dual spring tank configuration

Harness new "plug-in only" features like stereoized A/B Tank Select, Direct signal defeat, and BX 10 Tone controls

Mix with artist presets from Patrick Carney (The Black Keys), Vance Powell (Jack White), and Jacquire King (Kings of Leon)

Take a Listen

Take a Listen
5-Minute UAD Tips
5-Minute UAD Tips

5-Minute UAD Tips

Featuring the AKG BX 20 Spring Reverb.

Unparalleled Density

Unparalleled Density

The AKG BX 20's utterly unique character makes it a versatile tool for ambience as well as tone shaping. Its sonic personality features the quick onset of a classic plate reverb, and also the natural-sounding density and diffusion of a chamber — with little of the flutter or “boing” artifacts common with other spring reverbs. Unlike other spring reverb emulations, Universal Audio's hybrid delay network/convolution design provides the only plug-in representation of this mechanically controllable, acoustic ambience system. To that end, UA obsessively emulated a “golden unit” BX 20 from legendary producer, Jon Brion.

Spring Time

Spring Time

The BX 20 plug-in expertly captures the hardware’s unique two-stage decay. This yields warm, organic sounds whether it’s applied on percussion, vocals, or guitars, adding a unique timbre that can make individual tracks stand out — or melt away — in your mix. Short textures are chock full of colorful depth and dimension, while longer decays are rife with lush three-dimensionality, while never washing out.

New Features, More Control

New Features, More Control

The BX 20 plug-in provides the complete sound and features of the original, plus new "Mk II" features for an expanded sound palette. Tank Select provides the exact sound of the original A/B dual tank system, but includes a “stereoized” tank A or tank B, for more balanced stereo imaging. The Direct function allows you to mute the tank's direct signal for more control and minimizing conflict with the source audio — perfect for buses. The Baxandall-type tone controls — borrowed from the smaller AKG BX 10 — offers the last bit of seasoning to tailor your reverbs.

Watch The Reviews


      Input Select, Mono/Stereo: Changes input between summed mono or stereo
      Tank Select, A / B / A+B: Under stereo use, changes tank options among stereoized "A" and "B" and original "A+B" configurations
      Direct, Off / On: Disables/enables the spring tank's naturally occurring direct sound component
      Low Cut, Off / 80 Hz: 12 dB per octave, 80 Hz filter
      Bass, ±10: Continuous tone control borrowed from the AKG BX 10, ±8 dB at 150 Hz
      Treble, ±10: Continuous tone control borrowed from the AKG BX 10 ±4 dB at 5 kHz
      Dry/Wet, 0 to 100%: Continuously adjusts Dry and Wet signals under insert use case
      Wet Solo, Off/On: Disables/enables Wet Solo function
      Predelay, 0 to 250 milliseconds: Continuously adjusts Predelay amount
      Channel 1 Decay, 2 to 4.5 seconds: Continuously adjusts Channel 1 Decay time
      Channel 2 Decay, 2 to 4.5 seconds: Continuously adjusts Channel 2 Decay time
      Channel 1 Volume, ∞ to +24 dB: Continuously adjusts Channel 1 Volume
      Channel 2 Volume, ∞ to +24 dB: Continuously adjusts Channel 2 Volume
      Channel 1 Pan, ±100: Continuously adjusts Channel 1 Pan
      Channel 2 Pan, ±100: Continuously adjusts Channel 2 Pan
      Link, Unlinks/Link: Unlinks/Links Decay, Volume and Pan parameters
      Mix: Continuously blends processed and unprocessed signal
      Power, Off/On: Disables/Enables plug-in (all DSP processing is bypassed)

      Customer Reviews

      AKG BX 20 Spring Reverb

      Overall Rating

      C. Tunnessen

      January 25, 2016

      This thing is awesome!!!

      Sounds like a beautiful rainbow surrounded by magical unicorns… Ok sorry that doesn't make any sense at all! But don't ever doubt that this plug is totally amazing and perfectly captures the charm and magic of the original unit!! Thank you UAD you guys are a revelation!

      R. Bruno

      December 26, 2015

      Better than Auto Tune!

      To me Reverb is the original "Auto Tune"!
      I cannot and will not track without it.
      The BX 20 is by far one of the best Reverbs on the market.
      The Reverb just wrapps itsself around the vocals and helps
      create a moving vocal performance!!!

      E. Halterman

      November 27, 2015

      I liked the character but....

      I thought this one was a good concept and I have been pushing for UAD to get a good Spring plugin. With that being said this one has the character, especially for darker songs, but I was expecting more control over the plugin. According to my friends this is basically a perfect emulation of the original, but I don't know. It would have it's usefulness, but not an every dayer, like the EMT 140, 250 or the Lexicon 224. It's cool in it's own way though.

      J. Chase

      November 2, 2015

      Making The Decay Shorter

      D. McBride,
      If you want shorter decay times, you can an SPL Transient Modulator after the BX 20.

      The sounds is quite beautiful and will be very inspiring for artists while tracking, especially Vx.

      Will update after spending time with this.

      D. McBride

      October 13, 2015

      AKG BX20 spring

      It sounds beautiful and I don't regret the purchase Buuuuuut..... it would more often usable if the decay time could be made quicker. I had that issue with our EMT plate, I know its par for the course, but still....

      N. Brooks

      August 18, 2015

      Don't Fear The Reverb

      There are only one or two plugins that I've purchased within literal seconds of hearing them, and UAD's AKG BX20 is one of them. Not only is this an amazingly realistic emulation plugin (I cannot tell that it is a plugin. It sounds exactly like the BX20 I used for many years), it is rich with options that were not available on the hardware - such as the mixing of tanks, the option of "direct" signal in/out, etc... Also worth noting are the absolutely stellar presets which are included. Generally, presets are viewed by me as a "starting point", but in several instances, the preset on offer was absolutely perfect without any tweaking! Amazing product, Universal Audio!! By far and away, the best reverb plugin I've ever heard!!

      R. Virili

      August 14, 2015

      This one it's wonderfull

      All your plugin and all your emulations from now on must be of this quality... fantastic :-)
      and if the price is good, even better...
      Great job.

      S. Chahley

      August 14, 2015

      Absolutely magical....

      I own a large portion of the UAD plug in collection, and am a huge supporter - but this is the first time I've ever felt I needed to jump on here and review a plug in immediately after trying it out....I don't even own it (YET!)...

      I was using my usual spring verb plugin stand-by on a pedal steel last night, and got the urge to put this guy into demo mode and see what the difference was.....

      WOW!!! I can honestly say I almost cried! Suddenly the steel jumped to life in the mix, the emotion in the playing seemed so much more obvious....it sounded like the part was floating in a lush dreamy 3D soundscape. My jaw literally hit the floor! You've outdone yourselves, UAD emulation ninjas. Congratulations - this thing is next level....

      J. Klein

      August 14, 2015

      Stunning !

      Never used the hardware but : Since now my alltime favourite reverb plugin was the EMT 140. Now UA brought me a new favourite, this is the kind of plugin I long for : it has a character, a unque fingerprint, and it´s easy to handle. Instant mojo. Really well done.

      A. Link

      August 14, 2015

      Demo it against the EMT 140 and be amazed... "Spongey" indeed

      The most vibey and wide reverb there is in the plugin world. Just enter a different time for L and R and add more gain to the channel with the shorter time. I've experimented with some ducking on the RVB bus (from the kick) and it sounds incredible. The modern additions to this plugin are very welcome and it's fantastic to have two tanks to choose from. You really have to try this one because the sound is very unique. It is pretty slanted to the mid-range but not in an annoying way, quite dark, and spongey. If you are working on moody rock or rnb I feel like you would probably want to get this one. Compare it to the EMT140 and choose, I'd go for the BX20 if I had to pick one. Just wish they'd put another coupon in my cart :)

      M. Puigserver Barceló

      August 14, 2015


      Uad guys have done an amazing job. This reverb is wonderful! I've tried it in a couple of mixes with guitars and the space it creates is so natural that you really believe it was done with the hardware unit. A must have.

      B. Schulz

      August 13, 2015

      The big deal

      I love this reverb. This reverb is the only one I got to know so far that does not only sound very well.
      This one you can feel. And believe me it feels fantastic.

      My favourite reverb for vocals on ballads.

      M. Hoomans

      August 13, 2015

      Finally a spring reverb plugin I like!

      I have been playing with this reverb for a few days now, using it on guitar, drums, vocals and much more and every time it manages to add such a lovely warm space around the sound in such an unique way. I'm not going to say it will be my one and only reverb from now on, but it will be a very valuable addition to my reverb collection for sure, I can't wait to use it more often!

      s. othniel

      August 11, 2015

      AKG BX 20 Spings of Smooooooothhhhhh........

      Well I demo tested this baby along side the Lexicon 224 and the EMT 140 ( i have both ) and my question was, do I need another reverb plugin? Well the answer is yes, this one, I need the AKG BX 20. It's very different from the others, smoother, richer, definitely for vocals. This is like the LL Cool J of plugins......... worth the money, i have to buy it.

      D. King

      August 8, 2015

      Mr. Zebedee!!

      I have bought this already after 1 day of using the demo! Why put of the inevitable..
      This sounds great and having stereo control over the two tank saves the usually two plugs and returns setup.
      Sounds quite unique so well worth having in the tool box.
      Nice UA

      Thank you.

      D. Riggs

      August 7, 2015

      A plugin you did not know you needed.

      I've had so many spring reverbs that I have not liked in amps. Who needs another spring reverb, right! Wrong. This is a truly wonderful thing that really does add magic to your sound. A truly seamless wash of ambience behind a solo sound. I can't wait to experiment more with it.

      S. Boman

      August 5, 2015

      Holy cow!!!

      Finally!!! I've been wanting a proper spring reverb plugin for years and years.
      And finally UAD set the bar where it should be.
      I have a bunch of hardware springs(one AKG BX15)and this is the first plugin that gives them a run for their money!!

      Well done UAD!!!!

      G. Myklebust

      August 5, 2015

      Heaven !

      This is just a fantastic creation. Must be Heaven made !

      a. schinoff

      August 5, 2015


      It´s magic, musical and deep...Good Job UAD!

      S. Elmblad

      August 4, 2015

      Best spring reverb plugin

      This is a great spring emulation that in my opinion works best for kind of midrangey sounds that wants to swim a little. I can see myself using it for clean electric guitars, snare, a lonely trumpet or trombone and some voices, and maybe the occasional harmonica. I bet it works magic on a bariton guitar with some tremolo. Basically I bought it because I love to have options when it comes to creating space in a mix, and I like this one. A little quirky and weird, like a spring reverb should be. The added functions as a plugin compared to the real thing is highly welcomed.