Audio-Technica released a second powered-ribbon mic this year, the AT4081 ($895 MSRP), which it developed in tandem with the AT4080 [http://www.gearwire.com/audiotechnica-at4080activeribbonmicrophone.html]. The company’s active ribbon mics combine high SPL capability and a robust build quality with the smooth, rich sound that traditional, passive ribbon mics provide.

The AT4081, which has a smaller profile and lower price than the AT4080, offers a bidirectional pattern and requires +48V phantom power to run the in-capsule active electronics. The technology is based around a head amplifier that gives the mic a higher output level than a passive ribbon would have. At the same time, the impedance load is adjusted on the ribbon element to allow the mic to be used with preamps that would typically not have enough gain for a passive ribbon design.

Audio-Technica recommends the AT4081 for use as drum overheads and for recording horns, strings, acoustic instruments, and guitar cabinets. According to the manufacturer, every AT4081 is hand built with a strict attention to detail.

Just the Facts
At just under 7-inches long, and weighing less than 5.5 oz., the diminutive AT4081 can be placed in much tighter spots than the larger AT4080. The magnets in the AT4081 are powerful, rare-earth Neodymium, and the dual-ribbons—which move in unison—are mounted front-to-back, with one positioned slightly in front of the magnetic pole and the other slightly behind it. The ribbon motor is mounted behind a resonator plate that is designed to increase the mic’s high-frequency response (see Fig. 1). In addition, the AT4081 is enclosed in double layered grilles and features stabilized internal components. An ultra-fine mesh cage helps protect the transducer elements against damage from wind and plosives.

One of the main differences between the AT4080 and AT4081 is the noise level. With a self-noise rating of 25 dBA, the less expensive AT4081 is a full 3 dB noisier than the AT4080. However, the most noticeable difference is in each mic’s frequency response. The AT4081 has a flatter response—30 Hz to 18 kHz (+2/-8 dB)—than the AT4080—20 Hz to 18 kHz (±10 dB). Where the AT4080 has a significant bass boost below 300 Hz and a -3 dB dip at 3 kHz, the AT4081 is nearly flat, with no more than a decibel or two in deviation from about 60 Hz to roughly 12 kHz. Consequently, the Audio-Technica active ribbon mic you choose should be based as much on the sound you want to capture as the price point.

Fig. 1: An internal view of the AT4081’s ribbon assembly.

The mic handles SPLs up to 150 dB, offers a signal-to-noise ratio of 69 dB, and has a dynamic range of 125 dB at 1 kHz (when hit with a maximum sound pressure level). The accessories include an isolation clamp, a windscreen, and a carrying case.

Hearing is Believing
For testing purposes, I used a pair of Neve 1099 preamps and Cranesong HEDD 192 digital converters for material recorded at 24-bit, 96 kHz. I tracked much of the same instruments and source material that I did in the AT4080 review. In addition, I did a few side-by-side recordings of both Audio-Technica ribbon mics, just to get a sense of their sonic differences.

I began by using the AT4081 to record an acoustic guitar, strung with a Nashville string set, that has a sparkly sound favoring the upper frequency spectrum. The AT4081 captured the high-end of the acoustic nicely, but without the shimmer that my typical first call acoustic-guitar mic, a Neumann KM56 condenser, gives me. Instead, the smooth tone of the ribbon mic made it sound nice and furry the way a ribbon is supposed to, but aided by the active electronics that brings the tone out at a low-gain setting on the preamp.

I tried the AT4081 on a variety of acoustic instruments, including nylon- and steel-string guitars and a lap dulcimer, and the results were all good. When I blended in a KM56, set to a cardioid pattern, the combination was marvelous, giving me just enough brightness.

The AT4081 responds well to EQ adjustment. Even drastic EQ applications yielded good results—very much in line with my experience with passive ribbon mics.

Head to Head
At this point, I brought out the AT4080 and set the mics up together for a recording pass on an acoustic guitar with a beefy open tuning dropped down to C. The difference between the two ribbon mics was substantial, with the AT4080 getting much more of a boomy low-mid sound, and the AT4081 sounding a bit less full and vibrant, but still very nice. On some of the quieter passages, the AT4081 noise was noticeable, very similar to what I experience from the passive Royer 121 with the gain of the Neve 1099 cranked high. However, both mics did very well with the top end of the frequency spectrum.

Next I tried the AT4081 on some electric guitars, starting with my Silvertone strung in a Nashville-type tuning, going into a pre-CBS Fender Twin with a very clean sound dialed in (no pedals or distortion added). The AT4081 was placed twelve inches away from the right speaker cone, along with a Shure SM7 up against the grille on the left speaker. This is the same setup I used on the Twin when I reviewed the AT4080 and it gave me a chance to compare each of the mics when blended with the SM7, albeit with material recorded during two different sessions. Listening to the AT4081 track on the Silvertone on its own revealed the ribbon sound that I’ve grown to love with electric guitars. However, when I listened back to the material previously recorded with the AT4080, I heard beefier lows that the AT4081 didn’t capture with the same guitar/amp setup.

The AT4081 Active Ribbon Mic mounted in its included stand clamp.

Next, I recorded a Fender Stratocaster going into the clean sounding Twin. I placed the AT4080 and AT4081 on the left and right speakers, respectively, about a foot away, along with a Shure SM7 for an additional option. Blending and panning the two ribbons together was a treat: It gave me a very dense, rich tone. With judicious use of EQ and phase adjustment, and a bit of the SM7 added in, the results were stellar.

With this same setup, I recorded more electric guitar tracks with a variety of other electric guitars and settings, and the AT4081 on its own did very well in every configuration, whether the amp tone was clean or extremely crunchy. Having both Audio-Technica ribbon mics for my electric guitar setup proved to be a superb combo.

Finally, I recorded an accordion with the AT4081. I tried the mic at a variety of distances from the instrument, and settled on about 7 feet away to get a good balance of accordion and room sound. On quiet passages I could hear a bit of the AT4081’s self noise, once again similar to the sound of my passive Royer 121 when the pre-amp is boosted heavily to capture quiet material.

Get Active!
With a street price of $699, the AT4081 is competitively priced and an affordable option for an active ribbon microphone. When you do the math, the combined street prices of the AT4080 and AT4081 is almost equal to the price of a Royer R-122, one of the premiere active ribbon mics on the market. With that in mind, it would be tempting to buy both Audio-Technica mics just to have the option of recording two channels of ribbon mics, especially on electric guitars. Either way, the AT4081 is worth checking out, especially if you’re looking for your first active ribbon microphone.

Pros: Small. Lightweight. Relatively inexpensive for the sound quality.
Cons: A little more self noise than the AT4080.

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