We fought it. We struggled with it. We were in denial, and it took a good four months of nonstop use before we were completely convinced. We are forced to admit that Warm Audio has done the unfathomable: re-created the legendary LA2A compressor in all its glory—and then some. Doubters, haters, and the most hardcore skeptic (like us) can relax and rejoice, because sometimes dreams do come true. The Warm Audio WA-2A is “all that and a bag of chips!” It’s so good that probably want more than one of them in your studio.

Category Value Rating
Features 20% 3.5 Stars
Usability 25% 4 Stars
Sound 25% 4 Stars
Documentation & Support 10% 3.5 Stars
Price 20% 4 Stars
Overall: 3.9 Stars, which earns it a WIHO Award!
3.6 stars or better: Outstanding, WIHO Award
3 stars or better: Worth considering
2 stars or better: Suited to specific needs
1 star or less: Not recommended

No joke: With an MSRP of $899 you will be salivating at the thought that you could own two WA-2A’s for less than the price of one vintage LA2A. In fact, to really drive it home… you could buy three!!! Our first impressions were, “Wow, sounds great,” but we had unjustifiable concerns that the unit would break down or have some weird anomaly that wasn’t discovered initially, so that we could wryly smirk and say “Yeah, that’s why it’s so inexpensive.” This never happened, and slowly but surely, in one of our editor’s commercial studio facilities, this unit has become the go-to compressor on the front end for… EVERYTHING!!!

The Warm Audio WA-2A Optical Tube Compressor is not merely affordable, but it’s damn scary-close to the LA2A in design, operation, aesthetics, component quality, sound, and build. In fact, if you have a non-operational LA2A you could swap out the Opto-attenuator that’s in the WA-2A because the form factor is identical—not to say it’s an exact replica, because it isn’t. There are some nice design modifications that make the WA-2A even easier to operate than the vintage LA2A.

The bottom line is that if you always wanted an LA2A (who didn’t?) but could never afford one or justify the cost, those days are over. The Warm Audio WA-2A Optical Tube Compressor has torn down the wall! Hopefully you won’t be trampled by the hoards of other engineers running to get their hands on such a fantastic compressor for the studio.


The Warm Audio WA-2A is a leveling amplifier/optical tube compressor that has a sleek, classic look and uses a standard 19” Rackmount chassis, fitting nicely in a 2U space. True to classic opto-compressor designs, the WA-2A uses photo resistors (electronics that react to light) and an electro-luminescent panel that becomes brighter as audio signals increase. The WA-2A includes one of the best optical attenuators available: the Kenetek T4B.

The Warm Audio WA-2A functions as both a compressor and limiter, selectable via a front panel switch. All attenuation can be easily monitored via a VU meter located on the front panel and modified via the meter select. Options include gain reduction, and output (measured at +10 db or unity gain (+4db)).

In compression mode, the WA-2A acts as a standard signal compressor, while in limit mode it acts more like a hard limiter. The WA-2A can operate with compression ratios starting at approximately 4:1 and getting close to 100:1 (depending on the source audio and mode).

Following the design of the vintage LA2A, the Warm Audio WA-2A does not have compression ratio nor attack and release time knobs, but does have a peak reduction knob. This is due to the complex nature of the optical attenuator and its relationship to incoming audio signals. The WA-2A has a very fast attack (10 milliseconds) and a three-stage release time varying from 0.06 seconds for 50% release and 0.5 to 5 seconds for complete release. Additionally, the WA-2A provides up to -40db of peak reduction and +40db of output gain.

The rear features balanced inputs and outputs on both XLS and TRS jacks. In the better-than-the-original department, the WA-2A has a meter adjust knob and pre-emphasis control located on the back panel (rather than requiring use of a screwdriver as on the original LA2A). The function of the pre-emphasis control is to change the way the opto unit responds to incoming audio. Specifically, fully counterclockwise causes the unit to become somewhat of a low pass filter while the default position has equal response to the entire frequency spectrum (15HZ to 20 KHZ ). The unit has a standard IEC power connector and voltage selector. The unit can operate at 115vAC (60hz) or 230vAC (50hz). For legacy compliance, a grounding lug is provided.

If having more than one unit is in your future, the WA-2A also has a stereo link feature (Warm Audio recommends a TRS cable of no more than two feet in length).


The Warm Audio WA2A is a beautiful piece of hardware that looks lustrous and clean and is simple to operate. As stated earlier in this article, we were skeptical about a hardware compressor at this price point exhibiting any true characteristics of the vintage LA2A, but it does. We have an actual LA2A that was in use daily up until sometime during the review process. We were more than pleasantly surprised to find that this unit exceeded all expectations in terms of usability and similarity to the classic hardware.

Specifically, the simple design and straightforward operation of the WA2A made it a go-to unit that achieved quick and stunning results. We used it on everything including vocals, bass, acoustic guitar, electric guitar, snare drums, synthesizers, and various keyboards. No matter the task, the WA2A was simple to understand and we easily achieved great results.

Moreover, with only three front-panel knobs, even a complete novice could figure out how to get good results with trial and error. Recording and mix engineers would find it ridiculously simple to start using, quickly forget about technical things and getting right into making great sound. Case and point was the first artist we used the unit on: a San Francisco Bay-area group that included a striking alto voice.

Regardless of the vocal approach, both singers were able to relax and get inspired performances because there was no need for “bobbing and weaving” in the isolation booth. The smooth response of the WA2A allowed the artists to perform without worrying about vocal technique.

One of the design modifications that really helped with usability are the knobs on the back of the unit. Specifically, the VU meter and pre-emphasis can be adjusted easily, as opposed to the vintage LA2A, which required a screw driver to adjust the same controls. We’re glad that Warm Audio decided to make this minor design change.

In short, the WA2A is a breeze to use; even easier than its vintage predecessor.


What does The Warm Audio WA2A sound like? Well, it sounds like an LA2A, scary good and smooth, pretty much suitable for anything. Initially we were convinced there had to be a shortcut taken somewhere but there wasn’t. All the transformers, tubes, and optical cell were top notch. In fact, Warm Audio makes this clear by boasting the use of CineMag transformers. Bottom line is that corners were not cut with the components, and the sounds is a testament to that.

Just like the LA2A, the WA2A saturates audio with a smooth, rich character that has been sought for over half a century. We could go on discussing the sound but inevitably the best test is hearing it for yourself.

We have included three different vocal audio samples as well as a Taylor acoustic guitar with a lot of dynamics in the strumming.

First up on female vocals, in this case our featured artists is Natalyn Daniels. She has a very unique and dynamic voice that is also smooth, and our typical signal chain (UA LA610 into an 1176) could sometimes be too aggressive sounding. After only minutes on the WA2A Natalyn was gushing at the sound, and so were we. For all the vocal examples, the signal chain used a Blue Kiwi microphone into a Blue Robbie pre-amp, then into the Warm Audio WA2A. The acoustic guitar example was identical, except the microphone was a Neuman KM184.

Natalyn Daniels Audio Sample

Notice the warmth and thickness of the tone. What’s interesting to us is that there is still a lot of air on the top, and depth.

Our next example features Isabelle Murray singing in French. She has more of a mezzo airy voice, which still benefitted greatly from the WA2A.

Isabelle Murray Audio Sample

Last of the vocalists is Zach Grimes from Syde Project, who is an extremely aggressive hard rock singer. Again, the WA2A handled the task with flying colors.

Zach Grimes/Syde Project Audio Sample

Zach was hitting the compressor pretty hard and in spite of the huge difference in style and tone of his voice (compared to the female singers) the WA2A handled it easily.

Finally, we tracked a Taylor 810 acoustic guitar using the signal-chain mentioned earlier with a Neumann KM184. Again, the attenuation was smooth despite a large dynamic range.

Taylor 810 Acoustic Guitar Audio Sample

The WA2A easily compressed signals regardless of style or instrument. Additionally, it added the same thickness and warmth regardless of how aggressive the singer or instrument play was. Without any post EQ or extra processing, the raw sound is simply gorgeous and should sit nicely in a mix.

Documentation and Product Support

Warm Audio has all the expected resources such as specifications and an online manual. Additionally, there are some video reviews and supplemental documentation on their website. Further, the support we received from Warm Audio was fast, friendly and… warm like the company name. It’s obvious they enjoy making studio gear.


The Warm Audio WA2A sells for $899. To get a compressor/limiter of this quality and heritage at this price is unheard of. You’ll probably find more than a few of these in studios everywhere very soon.

Contact Information

Warm Audio

Evaluation Short-List

  • UA Teletronix LA2A (re-issue)
  • ADL 1000 C/L Tube Compressor
  • Teletronix LA2A Original (1960s)

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