All Diaphragms Great and Small
Large-diaphragm capsules are noted for their natural sound, low self-noise, high sensitivity and increased presence. However, the effective square area of the diaphragms requires them to be thicker and therefore more rigid and less reactive to higher frequencies. Because of their size, they also tend to have temperature-stability issues, and their sensitivity can be affected if the backplate-to-diaphragm distance has to be increased.
Small-diaphragm condenser microphones are noted for their wider frequency range, better dynamic range and higher SPL capability. By comparison, the lower-mass small diaphragm means they can be made thinner and are better able to track fast transients. But typically they are less sensitive and have higher self-noise than large-diaphragm microphones.
The AT5040 takes the best that both have to offer by incorporating four small, carefully matched, rectangular diaphragm capsules arranged in a two-over-two array in a frame that measures 60.5x35.5 mm. These permanently polarized (electret) capsules each measure 21.2x12 mm with a sizable vibration area. Functioning as one large diaphragm but without sharing a common backplate, this four-part element has a surface area twice that of a 1-inch circular diaphragm condenser capsule.
The four capsules each use diaphragms made of polyphenylene sulfide, or PPS, a polymer resistant to the effects of premature aging and most chemicals. The diaphragms are made from 2-micron thick material that’s aged, stabilized and embossed with A-T’s patented double-wave honeycombs—octagonal shapes that increase the diaphragms’ effective surface area while also strengthening its tensile strength.
Wires connected to the backplates of each capsule are routed to a proprietary summing matrix that uses all-discrete FET (field-effect transistor) amplifiers to combine them to a single output.
Typical 48-volt phantom power drain is 3.8 mA to power the amplifiers (for reference, a Neumann U 87 Ai draws about 0.8 mA). A-T went with electret capsules to avoid using even more phantom power current required for the four DC-to-DC converters necessary for externally biased capsules. There are no roll-off filters, attenuator switches or user-serviceable parts in this handmade microphone.
To decouple from the external microphone body, the quad capsule assembly is suspended at two points from the top of a stainless steel frame using two rubber shock-mounts. The bottom of this frame is machined into a plinth that acts as a stable base resting on rubber shock absorbers to isolate it from the top of the amplifier circuit frame below. At the bottom of the amp circuit frame is a rubber gasket allowed to compress when the entire assembly is inserted into the microphone’s body, which includes a large stainless steel double-layer mesh windscreen.
The windscreen uses two different mesh sizes welded together and is bifurcated by a vertical reinforcement frame connected to the windscreen itself that mechanically stiffens the whole mic assembly.
The AT5040 comes with the AT8480 locking shock-mount assembly. The capsule “clicks” sideways into the assembly’s floating gripping mechanism that clamps the microphone’s aluminum/brass body gently yet very securely and without marring the finish. Once the lock switch is thrown, the AT5040 can be angled freely, inverted from a boom stand, or positioned in any way with confidence that the 20.5-ounce mic will not drop out of the mount.
On the Job
The first time I used the AT5040, I was immediately struck by its nuanced and delicate presence coupled with its super-accurate detail. Like a powerful microscope, it captures everything—warts and all—especially true for loud guitar cabinets. You might not like what this microphone tells you about your amp and your speakers—stuff you’ve never heard before using your SM57! Also interesting is that, for a cardioid polar pattern, the proximity effect is less compared to other vocal condenser cardioid microphones I’ve used.
I also found my choice of microphone preamp(s) more noticeable in their effect on the overall sound quality, depending on the sources and how loud or soft they are. The AT5040 is a modern microphone with plenty of output level that may exceed the dynamic range (headroom) of your console or stand-alone preamp when recording close and/or loud sources.
The microphone’s dynamic range is 137 dB with a 5dB (A-weighted) noise floor—so low that any added signal chain noise and distortion from compressors or EQs is easily heard. Maximum input sound level is 142dB SPL, and recording close and loud guitar or bass amps—even a snare drum—is no problem, but a preamp capable of minimal mic gain will be required if you don’t use an attenuator pad.
For vocals, I found a precise and accurate sound: not overly bright but with sibilants heard clearly, clean and consistent. The AT5040 has a wide cardioid pickup pattern that seemed to lessen the effects of loss of clarity when singers get slightly off-axis on certain phrases and words. If I listened to the singer’s loud headphone mix, I could hear a definite sweet spot for optimal sound for vocalists who can stay on-point and at a consistent distance.
For this initial test, I used no additional outboard signal processing when I recorded a high tenor male vocalist who sings ballads very quietly. He sang about six inches from the pop filter placed right on the microphone. I found more than enough level with the API 1608 console’s preamp gain at minimum and no pad. To find the sweet spot, it is easy to experiment with mic-to-source by just small changes in mic gain, and usually there is no need for the pop filter unless you want singers closer than four inches.
For a different singer at another studio, I used about 15 to 30dB gain from my RTZ 9762 preamp (Neve 1272 circuit) for medium-to-loud singing within six inches of the mic. Great results—the singer himself, listening on headphones, even commented on the noticeable improvement over the Neumann U 87 Ai they had been using. The AT5040 has a smoother sound with less upward treble tilt, and with a touch of compression from an LA-2 leveling amp and no EQ, the vocal tracks were mix-ready.
I used an Ingram MPA685 (variable-impedance) preamp for the next vocal recording test at another studio. I liked using the preamp’s 2,500-ohm (high) input impedance position and the -5 to -9 gain positions (around 17dB of gain) for recording my loud rock singer. Again, the 5040 effortlessly captured everything right and wrong with his performance.
I recorded a Martin OMCPA-4 guitar in a large, wide-open tracking room and got the best sound for finger picking with the mic about 12 inches from the 12th fret and with about 40dB of mic gain from the studio’s Duality SE console preamp. Lowering the gain 5 dB and keeping the same distance but moving over the sound hole produced a thicker tone as expected, but not with excessive bass buildup. The AT5040’s pickup pattern provided wide coverage of the entire instrument in a balanced way, including the player’s very light foot tapping. Like when using a small-diaphragm condenser, aiming the AT5040 where the pick hits the strings (or not) dials in the “mix” of articulation/high frequencies versus the rest of the instrument, as you require.
Initially, more as a whim, I put the 5040 midway between the dust cap and surround of one of the speakers in a bass amp cabinet. It was the best clean bass amp sound I ever got. It sounded like the DI, only with slightly more “hair.” The amp was set to low volume, and the recording was as present as the passive DI version—just with more personality.
The AT5040 offers the elegance and natural sound of a well-designed large-diaphragm condenser microphone with the precision, wide frequency response and high SPL handling of a small-diaphragm microphone. The AT5040 is like super high-definition video—it captures everything in truthful resolution.
Barry Rudolph is an L.A.-based recording engineer. Visit him at www.barryrudolph.com.
Product: AT5040 Studio Vocal Microphone
Pros: Wide dynamic range, low noise floor and hyper-accurate rendering of the source.
Cons: May be too accurate for some applications.
I found new life for an old trick when recording vocal doubles or stacks of double-tracked vocals using the same singer. Have the singer move to one side of center or change distance to the microphone for recording the double-track. For the first, or primary track, the vocalist would be on-center and lined up on the AT5040; then for the first double, I’d ask the singer to move 30 to 45-degrees off-axis to the right. For the triple-track, I would ask the singer to move the same to the left side. This is an old trick, but the AT5040’s high resolution makes the different mic-to-source distances and their effect more “hearable.”