Warm Audio WA12

Joseph Colmenero



Warm Audio WA12

There are so many ubiquitous terms in the audio industry: bright, brittle, beefy, fat, punchy.  For those who like to make a discussion more frustrating, you can say brown, purple or green. Perhaps the king of audio adjective is “warm” – saying something is “warm” can mean a broad spectrum of audio qualities. Is it with less high end, lower added harmonic, slow slew, head bump, tape, tube, transformer, saturation…the list goes on. But overall, the dominant meaning of “warm” when referring to do audio is how much it reminds you of vintage analog. That sound you can’t seem to get with your IC preamp and your icy DAW environment. Naturally, naming your audio company Warm Audio will bring with it a certain level of expectation.

Warm Audio currently makes one product: the WA12 Discrete Mic Pre. The design is based on the classic API 312 mic amp module. Many companies like BAE and OSA have made clones for 500 series racks and can cost around a grand. WA12 is at a very reasonable $449 US. What’s more impressive is the guts of this thing are top notch. It’s completely discrete with dual custom wound USA made Cinemag transformers and a 1731 style opamp (the ones used in the original 312). Even though it follows the 312 schematic, it’s important to note that the WA12 is certainly it’s own thing.

Ok so what do we have here? Open the box to a half-rack sized chassis with a blood orange colored face. From left to right, the front layout is a ¼” input, switches that read HI-Z, +48V, PAD, POL (polarity), TONE, a gain knob that goes from 29-65 and a POWER button. Each button has a corresponding red LED as a helpful reminder that the switch is depressed. On the rear: a combo jack for microphone input, two balanced outputs (one XLR and the other TRS) and the 24V AC external power supply input (included).

It was interesting to find out that you can power the unit with the Golden Age Projects PS-AC4 power supply. This way you can have one power supply for several WA12s or GAP PRE73s. You can also use this so you can use different country’s outlets.

In use:

When I took the WA12 home I had a few voiceover jobs lined up. We had a few scripts to go through with the male talent, with each requiring a different character voices. I plugged in my AKG C414 ULS, and right away I noticed that this pre has loads of gain. Voiceovers require a quiet mic pre that can boost up the level of conversation volume performances.  A few clicks of the great feeling gain knob to about 9 o’ clock and I was in a good place. The sound was very solid, the low end was tight and low mids around 200-300hz were especially sweet and not boxy.

I played with the tone button a few times (when something is labeled “TONE” how could you resist?). It’s not a feature on any other 312 clones so I was intrigued. Seemed to boost the gain a few db, give the audio a beefier low mid and smooth out the esses in the voice.  Taking a look at the manual showed me that the “TONE” button changes the impedance from 600 ohms to 150 ohms. This is really cool! You can get up to +71db of gain for ribbon mics and you can play with loading to get another flavor of tone and saturation.

Next, I tried out the direct in with a bass guitar with EMG active pickups. Hitting the HI-Z button turns off the back combo input and sends the front instrument jack into the entire preamp circuit, transformers and all. I like to play my instruments wide open and I kind of wanted to be able to bring the gain down even lower. I had to put in the pad and bring the gain all the way down. Maybe an output control would be nice so as to experiment with driving the sound. The sound was very solid and detailed. It handled each note with balance and I was impressed with how much it made me notice the sonic texture of my fingers on the strings. With the TONE engaged the sound gets much more sub lows, and I could really feel the difference from my subwoofer. This would be perfect for synths.


  • Loads of gain with low noise (perfect for ribbon mics)
  • Tone switch gives a whole new flavor
  • Great value for what it costs
  • Delivers on it’s name sake
  • Power compatible with the Golden Age Projects PS-AC4
  • TONE!!!


  • No band pass filter
  • Couldn’t seem to attenuate enough for active instruments
  • I find wall warts annoying

The Warm Audio WA12 is a really great value for $449. This is a great take on the API 312 design. You get an all-discrete vintage sounding mic pre with custom U.S. made transformers. It’s quiet with loads of gain and has that sweet “TONE” switch. I would suggest following the WA12 with something like a compressor so you can find that sweet spot in the gain without clipping your recording input.