Shure SM7dB Dynamic Vocal Microphone—A Mix Real-World Review

New York, NY (January 22, 2024)—Originally released in 1973, the Shure SM7 Vocal Microphone (updated in the early 2000s to the SM7B) joined the SM57 and SM58 as one of the company’s three moving-coil, cardioid, dynamic models based on the Shure SM5 Series Boom Microphone, which was introduced in 1964.

All three—57, 58 and SM7B—now employ a variation of the Shure Unidyne III element, though the SM7B’s diaphragm design, along with additional acoustic space behind it compared to the other two, allows for more low-frequency extension and an overall flatter response. Other primary differences are the SM7B’s “yoke,” or gimbal mount, an internal “air suspension” shock-mount, and a large foam windscreen. The SM7B also featured two frequency response switches on the rear of the mic body.

The new SM7dB is the first upgrade or variant of the SM7B in 20 years, and for the first time, Rodger Cloud has licensed a custom Shure-designed, built-in preamp tuned by Shure engineers specifically for the new mic.

The SM7dB has three operating modes: Bypass and two Preamp modes, with either +18 dB or +28 dB of additional gain. These are set with slide switches on the back of the mic and replace the original’s (without preamp) flush-mounted filter switches. The preamp requires +48-volt phantom power, but you can leave it always on and freely switch back and forth between the original SM7B in Bypass mode and then the SM7dB with the additional gain if you like it.

In Bypass mode, the mic’s XLR connector is directly connected to the mic element’s coil, and no phantom power is required. When sending the mic for review, Shure assured me that Bypass mode sounds exactly like a SM7B in every way, with the same output impedance of 150 ohms and the same sensitivity of -59dBV Pa.

However, with phantom power switched on and in either Preamp mode, the output impedance drops to 27 ohms and the rated sensitivity increases to -41dBV/Pa for the +18dB boost position, and -31dBV/Pa for the +28dB boost. Just for reference, a Shure SM57 has an output impedance of 310 ohms and a sensitivity of -56dBV/Pa, while the typical Neumann U87 Ai condenser is rated at -28dBV/Pa sensitivity.

The +48-volt phantom power is required for the SM7dB’s active modes, and you can freely switch between them while phantom is applied without problems. As a standard procedure, however, you should always mute the channel/mic preamp inputs connected to the SM7dB’s output before initially switching on/off phantom power.

A MAJOR UPDATE

It’s been about 20 years, so the updates are substantial, including four easy-to-adjust slide switches to replace the recessed switches used in the SM7B. These switches change between Bypass, +18dB or +28dB of boost, and both the high-pass filter and presence boost on/off.

According to the included chart, the highpass filter, or bass roll-off, starts at about 350 Hz and continues down to 50 Hz. The Presence boost starts at 900 Hz and continues up to about 7 kHz, with a maximum boost never more than about 4 dB. In fact, the microphone is “ruler-flat” in response from 1 kHz to over 4 kHz.

The effects of these filters are the same in either Bypass or Active modes, and the same as the original SM7B microphone. However, the new slide switches are easier to use but protrude slightly, precluding the use of the rear security cover plate that was supplied with the SM7B.

The SM7B’s popularity stems from its wide range of uses—everything from radio station DJs going out over the air to recording engineers tracking loud singers, guitar amps and drum kits. It is a full-range, rugged, dynamic microphone, though for very quiet sources— whisper vocals, fingerpicking guitar parts, or certain percussion instruments—obtaining a proper recording level requires about 60 to 75 dB of mic gain.

For the professional recording engineer using proper gear, this low output is not an issue, but it can be problematic for the inexperienced or beginning artist/producer/engineer using an inexpensive USB interface and expecting condenser microphone-like performance and sensitivity.

Recently, major USB audio interface manufacturers have recognized this and have upgraded and released new models/versions of their preamps, with more gain for any microphone.

IN THE STUDIO

For some of my tests, I turned to a Millennia HV-37 stereo preamp, which contains two HV-35 microphone preamp circuit boards, with up to 70 dB of gain with the ribbon mic switch in. This is the proverbial “wire with gain,” a directly coupled amplifier design that uses no transformers in the audio path. The true sound of the source is revealed with no analog color added.

I work in Pro Tools HDX Ultimate, and all listening and recording tests were done at 24-bit/96 kHz. The outputs of the HV-37 were directly connected to my Crane Song Interstellar analog-digital converter and master clock, and all playbacks passed through the DAC within my Avocet 2 Monitor controller.

With the SM7dB in hand, I decided to try a microphone “shootout” as part of a quest to find the best mic for an upcoming vocal session. I placed my singer about an inch away from the end of the SM7dB, and about the same distance from a metal windscreen I typically use in front of a Soundelux/Bock U195—a condenser mic with a 1-inch dual-backplate K67 capsule in a fixed-cardioid polar pattern.

Both mics had no roll-off switched on, and I used the +28dB position on the SM7dB with its stock foam windscreen. The mic comes with two foam screens that basically allow a singer to “eat the microphone” without much “p” popping. Plosives are ancient history now. Plus, the SM7B and now the SM7dB have internal metal “cages” that provide about three additional inches from the mic’s front to the actual element inside.

Back to the shootout. The outputs of the two channels of the HV-37 were directly connected to the two line inputs of the A/D converter through VoVox Sonorus audio cables. These high-end cables were also used for connecting each mic to the HV- 37’s mic inputs—no patch bays or patch cables. I ended up using only slightly more preamp gain for the U195 to match recording levels.

The differences were stunning! The SM7dB is a drier-sounding mic, meaning it seems to only pick up what is directly in front of it, with very little of the surrounding room included. It provided a warm sound with minimal proximity effect, and it didn’t bring in too much “air” or cut the upper midrange frequencies. (The condenser had more air and upper-midrange clarity and more deep bass pickup). For a very loud singer, the SM7dB is the one, and being able to switch in additional gain right at the mic is definitely advantageous for soft, spoken-word podcasts or whisper-quiet singers.

In my tests, I tried the SM7dB on many different sources and compared it directly to an original SM7B in the studio. There are really no differences but I did have a problem re-orienting the gimbal—the U-shaped mount that you have to completely take apart to change its orientation.

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The SM7dB comes ready to go for an overhead boom, as seen in radio stations and podcast videos, but I wanted to use it on a mic floor stand or short stand and boom. Flipping the mic over inverts all the lettering, and if you’re okay with that, you can use it right out of the box.

For drums, I found the SM7dB excellent when both close to snare drums and inside the front hole of a bass drum aimed at the beater head. The Bypass mode, along with the Presence boost position, worked great for recording a kick drum, giving me a good but not excessive “point,” or edge, without EQ or compression.

On snare, it reminded me of using the world’s best—a brand-new Shure SM57, another popular snare drum mic, though the SM7dB brought out a bigger low-frequency “size.” Loud electric guitar amps had similar results.

Another fine addition to the mic locker, the SM7dB is ready to provide an upfront, clear sound no matter how loud or how soft it is and using any mic preamp. It is a big winner!