The Audio-Technica AT4050ST ($1,625 MSRP; $1,299 street) is a stereo version of the company’s popular AT4050 side-address, condenser microphone. With independent cardioid and figure-8 elements configured in a mid-side arrangement, the AT4050ST gives you the option of selecting internal matrixing to get traditional left/right stereo imaging without an external device. The L/R stereo settings include a wide stereo pattern (127 degrees) for increased ambient pickup, and a narrow pattern (90 degrees) which offers more direct sound and less ambience. In M-S mode, you get the discrete mid and side signals which you can matrix later—a major benefit of this recording technique.

Mid-Side differs from other stereo techniques because it records, as two separate channels, the mid (center) channel using a cardioid pattern (capturing whatever is directly in front of the mic) and the side channel using a bi-directional mic (capturing 90 degrees to the left and right of the center of the soundstage). By themselves, they do not give you stereo playback—they need to go through a matrix to create a traditional L/R image. Because the AT4050ST has an onboard matrix, you can get a normal stereo image immediately, if needed. However, by recording discrete mid and side signals, you will have full control over the width of the stereo field after the recording takes place.

Like the AT4050, the AT4050ST has a frequency response of 20 Hz to 18 kHz (+5/-10 dB), a –10 dB pad, and a low-cut filter set at 80 Hz (with a 12 dB/octave slope). Instead of having the former’s switchable polar patterns, the AT4050ST has two fixed-pattern capsules with selectable stereo settings. All of the other specs of the stereo mic are similar to the AT4050, depending on which stereo pattern is chosen. Remarkably, the two mics weigh nearly the same—about 18 oz.

The AT4050ST comes with a multipin cable, a shockmount, a dust cover, and a case. My only beef with the mic is that it doesn’t feel secure in the shockmount when the assembly is placed in a horizontal or slightly angled position, such as when used as drum overheads.

Audio-Technica recommends the AT4050ST for nearly every application that requires a stereo microphone, such as drum overheads, acoustic piano, string ensembles, vocal groups, and acoustic and bluegrass bands. It also recommends moving the microphone closer to a sound source when using the internally matrixed modes (e.g., if you’re not recording the mid and side channels unmatrixed), in order to enhance the width of the stereo image and decrease room ambience. Of course, moving the mic away from the sound source will result in a narrower stereo image and more room sound.

Recording Far…
For testing purposes, I used a pair of Neve 1099 preamps with a Cranesong HEDD 192 digital converter, as well as Brent Averill Neve 1272 preamps running into a Metric Halo Labs Mobile I/O converter. The recordings were done at 24-bit, 96 kHz.

I began by tracking a hodge-podge of a percussion kit (the same set-up I put together for my review of the AT4080 ribbon mic) made up of a snare, a cymbal, and some percussion instruments. I switched the AT4050ST to the 127-degree (wide) setting, placed the mic about 6 feet above the kit (facing downward), and recorded a pass. The result was clear and relatively uncolored, with a wide stereo field that included plenty of room sound.

Fig. 1: An internal view of the AT4050ST, showing the configuration of the mid (cardioid) and side (figure-8) capsules.

Next, I moved the AT4050ST closer—about 3 feet above the center of the kit—to further increase the stereo image of the instruments while reducing ambient sound. The difference was clear, with the percussion kit filling the stereo field. When I switched to the 90° setting, the stereo image narrowed as expected.

After trying a variety of distances and mic settings, I eventually settled on the M-S mode, with the mic in the far corner of the room about 12 feet away. It’s a setup I have used in this room numerous times, using a pair of Neumann U67s as the M-S mics. However, this time I added an AT4080 ribbon mic close to the kit, about 3 feet overhead. I recorded a few passes and put together a simple groove. Then I tracked some variations so I could assemble a song to use as a test template.

I kept the AT4050ST up in the corner in M-S mode and tracked a variety of stringed instruments. These included an assortment of acoustic guitars that covered most of the mid- to upper-end of the frequency spectrum, as well as some high-frequency instruments such as an autoharp and a six-string lap dulcimer. The results were excellent when it came to capturing the room sound. It was significantly less colored, though lacking in low end, compared to my U67 M-S setup in the same spot. I added a KM56, in cardioid mode, as a close mic on the instruments and eventually recorded an A, B and C section for my song using a Larivee acoustic guitar.

Next, I had a friend of mine bring over his stand-up bass and I did a few short duets with him with the same mic setup. By itself, the AT4050ST didn’t quite get the low-end of his bass that I wanted, compared to the U67s in this configuration. But, of course, there is a large difference in price and capabilities between a pair of U67s and an AT4050ST. Placing the AT4080 ribbon mic close to his bass, I pulled up the looped groove and recorded a few bass lines for my song.

…and near
Now that I had the basic layout of my song worked out, I wanted to see how the AT4050ST sounded as a close mic on a variety of acoustic instruments. I started by recording my daughter’s 1⁄2-scale, nylon-string guitar with the mic set to 90 degrees and placed about 10-inches away from where the neck meets the sound hole. The results were clear and intimate with the image of the guitar splayed out across the stereo field. I switched in the 80 Hz high-pass filter on the mic to get rid of some problematic string thumping and recorded a few passes.

With the mic in the 120-degree setting, I recorded a few more tracks, then edited the material so that the A and B sections of the song each had different stereo widths as determined by the AT4050ST settings. The differences were obvious, and it lent a nice spatial change within the song. For the C section of the song, I created a mono track using only the right channel of the 90-degree pass.

Going Electric
Next, I tried the AT4050ST on an old Silvertone electric guitar, strung in a Nashville-style tuning and running through a pre-CBS Fender Twin at a clean setting. I switched the mic to the 127-degree mode and placed it about 3-feet away from the amp, adding the AT4080 ribbon mic next to the left speaker. After a few overdub passes and some quick editing and volume rides, I was able to make the electric guitar bigger and wider on the B section, thanks of the AT4050ST material.

When it was time to add vocals to the song, I placed the AT4050ST about 4 feet away and kept a Neumann U47 up close. I used the same process as before on the AT4050ST—switching between the two different widths for different sections of the song. After adjusting the phase on the U47 material, I had a lovely, stereo vocal track. On the main vocals, I added more of the AT4050ST material during the song’s chorus and the result was a cool “hyper-stereo” effect, with plenty of room sound.

Using only the AT4050ST in M-S, I did a final pass to capture some background vocals and finish off the song. With judicious use of the stereo elements in the mix, the final piece offered a wide range of variations in ambience and room sound thanks to the different stereo options this mic offers.

I tried the AT4050ST on other instruments, including an accordion, an upright piano, and a homemade percussion instrument built from empty CO2 tanks. The results were always frequency rich and spatially interesting. The piano was particularly fun, as I moved the AT4050ST around to get a thunderous, close-miked, hyper-stereo boogie-woogie.

3-in-1
The overall sound of the AT4050ST is clear and fairly transparent, and it works well in a wide variety of stereo applications, including as a room mic. It is, however, a little light in the low-end when used for distance miking.

With a street price of $1,299, the AT4050ST makes a viable and economical option for any recordist who wants the flexibility of having three very different stereo configurations in one microphone.

Pros: Well built. Three stereo modes. Mid-Side capabilities. Internal M/S matrix option.
Cons: Doesn’t feel secure in the shockmount when placed on an angle.

Walt Szalva owns and operates Planet-3, a full service audio production studio located in San Francisco.