Following on from the previous article on the DBX 160A compressor, this review will focus on my newest outboard gear purchase, the Warm Audio WA-2A optical compressor.


The WA-2A is Warm Audio’s take on the classic Teletronix LA-2A, a compressor that is widely considered to be one of the best ever made. Originally designed in the early 1960s, the LA-2A is a tube-based ‘optical’ compressor, meaning that the unit operates by pairing light dependent resistors to an electro-luminescent panel (ELP); the ELP is driven by the audio side chain, becoming brighter as the incoming audio gets louder, which in turn increases the amount of resistance generated by the light-dependent resistors and attenuates the audio source that is passing through the unit.

The nature of the optical circuitry in the LA-2A attributes a distinct sound to the unit, which has proven desirable to this day, and as a result many companies now market their own versions of the LA-2A design, which originally ceased production in 1969. The expensive nature of the components required to create the the aforementioned circuitry however has traditionally meant that both the original and newer LA-2A style units have carried an inherently hefty price tag, meaning that only studios and serious hobbyists are likely to own one. But not so with the newest contender on the block, the WA-2A, as Warm Audio’s latest offering is roughly one third of the price of Universal Audio’s own LA-2A, which is pretty astounding; moreso given that the internals of the WA-2A are of the closest spec possible to the original, with the design also allowing you to swap out some of the existing components with those of the original (if you can source them…).

I have been a huge fan of the plugin versions of the LA-2A since being introduced to IK Multimedia’s T-Racks White 2A a number of years ago and it is one of my go-to plugins when mixing vocals, bass and guitars. With this in mind and given the (relatively) low price tag of the WA-2A, I felt it would be a worthy addition to my hardware collection.



The WA-2A is sleek looking, if somewhat plain, coming in a 2U rack size, with an off-white/light grey faceplate, black legending and striking orange logo. In the centre of the unit is a large, illuminated VU meter that can be switched to show gain reduction or output level (in +4dB or +10dB variants).

The controls on the front consist of two finely-detented rotary pots that control the output (makeup) gain and peak reduction (compression amount), a three point rotary switch to change the function of the VU meter (as detailed above), a switch to change the compression type between limiting or compressing, and finally a switch for powering the unit on and off.

On the back of the unit are two balanced input sockets (one 1/4″ jack and one XLR), two balanced output sockets (one 1/4″ jack and one XLR) and one balanced 1/4″ jack socket with accompanying calibration pot for ‘stereo strapping’ to another WA-2A unit. Also featured is a rotary pot for setting the ‘Pre-Emphasis’ of the unit, allowing you to control whether it is more sensitive to higher or lower frequencies, and a rotary pot for zeroing the needle on the VU meter when it’s set to show gain reduction.

Whilst on the subject of the layout of the unit, I have always wished that the two main rotary pots were positioned the other way around, with the peak reduction on the left and the gain on the right. The reason for this is that when I originally started using the plugin versions of the LA-2A I instantly assumed that the ‘Gain’ pot was used to control INPUT gain, simply because of the fact that it was positioned before the peak reduction pot; had I read the manual first I would have know that this wasn’t the case, but in terms of the logic of the layout it still doesn’t quite make sense to me. With the WA-2A however, Warm Audio have seemingly addressed this issue simply by prefixing the word ‘Output’ onto the label for the gain pot, instantly clarifying the situation.


With only three main controls on the front panel you would expect the WA-2A to be extremely simple to use, and whilst it is very possible to achieve good results quickly, the complex nature of the ELP and resistors, coupled with the tube-based circuitry means that there is actually a lot of scope for creating different sounds and textures, especially when the source signal is driven into the unit at higher levels. The compression ratio in ‘Compress’ mode is fixed but, according to the manual “somewhat source dependent”, and switching to ‘Limit’ mode raises the ratio “much closer to infinity” for harder transient dampening, but the audible difference only becomes really apparent when operating on higher-level signals, providing plenty of scope for experimentation. Even when running a sound through with the peak reduction pot rotated fully anti-clockwise (no peak reduction), the WA-2A still adds a subtle richness and warmth of tone that is pleasing to the ear and seems to add life to the source material.

I was mainly interested in the WA-2A for mixing applications, but since acquiring the unit I have also made good use of it when tracking vocals and electric guitars. In placing the WA-2A directly after the preamp in the recording chain, and typically setting it to ‘Compress’ mode with a small amount of peak reduction it was easy to catch some of the louder peaks and gently smooth out the level of the recorded signal, also adding the ‘warm analogue’ sound that the original LA-2A is famous for. When recording electric guitars through DI, I was careful to take into consideration the tube-based circuitry of the unit, keeping the output of the preamp low for a more subtle sound, or cranking it up to add some sizzle and subtle distortion where desired.

When mixing, as with the LA-2A plugins, I primarily utilise the WA-2A on vocals, guitars or bass, using it to control not only the dynamics of the performance, but to warm up and ‘solidify’ the sound. To provide you with an example of just how effective the WA-2A is on vocals I have included a link below to a song called “Stormen” that I recently mixed and mastered for Swedish rapper Janulf. I ran the lead verse vocal firstly through a UAD 1176LN compressor plugin and then out through the WA-2A unit, giving it what I felt was a solid presence with just a hint of tube grittiness that helped to dominate the centre of the mix.

As with my previous article on the DBX 160A, when testing the WA-2A I wanted to not only review the hardware on its own merit, but also offer comparisons to some of the software equivalents on the market, including audio samples to help illustrate the results. For the purpose of testing I wanted an audio source that could demonstrate not only the effect of the dynamics processing, but one that would also benefit from the addition of the tonal warmth, so I dug out an acoustic guitar sample that I had recorded a number of years ago. The original guitar sample can be heard below:

Guitar Sample – Original

Note how the sounds of the pick are occasionally distractingly loud and that the overall tone of the recording sounds quite ‘thin’. Here is the same sample after being passed through the WA-2A with no peak reduction:

Guitar Sample – WA-2A (no peak reduction)

The issue of the pick transients still remains, but the overall sound is slightly warmer and fuller thanks to the subtle addition of analogue harmonics. To tame the dynamics of the sample I set the peak reduction to 35 and the output to 30, setting the unit into ‘Limit’ mode.


In this instance the higher compression ratio afforded by the ‘Limit’ setting meant that I was able to deal with the major peaks in the sample without having to apply too much overall peak reduction, creating a nicely rounded, balanced sound. You can still hear the dynamics of the pick as I didn’t want to squash them completely, but they are no longer as distracting:

Guitar Sample – WA-2A (peak reduction)

Next I set about running the same sample through the three of the popular plugin variants of the LA-2A:

IK Multimedia – T-Racks White 2A

Native Instruments/Softube – VC 2A

Universal Audio: LA-2A Legacy

As is to be expected with any audio plugin that emulates real world hardware, there will always be slight differences in sound between each variant, as the hardware units tested by each manufacturer in order to create the plugin will have been from different production runs and time periods etc. This is clearly demonstrated in the above screenshots, which show the settings I used on each plugin to attain the closest sonic match to the resultsĀ  obtained from the WA-2A; I primarily focussed on achieving the same audible level of dynamic reduction, whilst keeping the overall loudness level balanced to around -23 LUFS. Below is the guitar sample after being run through the WA-2A and the three plugins:

Guitar Sample – WA-2A Hardware

Guitar Sample – White 2A Plugin

Guitar Sample – VC 2A Plugin

Guitar Sample – UAD LA-2A Plugin

As you can hear, the plugin versions stack up fairly well against the hardware. They each have subtle differences, for example the VC 2A is the brightest sounding to my ears, and none of them quite have the richness in body from the additional low-mid frequencies that the WA-2A-processed sample has, but each plugin is still highly competent at creating the sought after sound that the LA-2A is famous for.


Needless to say, I do not regret my purchase of the Warm Audio WA-2A one bit. Having never had the opportunity to use an original LA-2A, I was basing my comparisons on the plugin versions that I had grown to love and rely on in my mixes, and in this regard the WA-2A has exceeded my expectations. It definitely has THAT sound, making it versatile enough to breathe new life into pretty much anything you run through it, and although the price tag is still not exactly cheap, it is definitely the most affordable version of any LA-2A style compressor on the market to date.