Audio Review: Shure SM27 Microphone
A decade ago, Shure Brothers made a splash with the introduction of its KSM series of microphones. Shure has enjoyed legendary status in the domain of handheld dynamic microphones used in both live and recording settings, but the KSM series was the company’s first excursion into side-address, large-diaphragm condenser mics, and this series has enjoyed great success. One of the mics in this series, the KSM27, has been discontinued—to be replaced by the SM27. This mic, which lists at $460, has a typical street price of $299. I was excited to get my hands on this mic to put it through its paces.
The mic sports a matte black finish and is just over six inches in length and two inches in diameter at its widest point. From the mid-point along its longer axis, it tapers in both directions, a bit more gently toward the business end, where the mic’s black grille houses its capsule. Toward the other end, the taper is a bit less gentle. It’s a sleek and attractive microphone, although I always have reservations about using significantly tapered microphones in generic clamp-style shock-mounts, particularly when they have a metal surface that doesn’t provide a lot of grip. I would strongly recommend leveraging gravity by keeping the microphone upright when possible if such a generic shock-mount is to be employed. One certainly would not want the mic to slip out and take a nasty spill. The mic does feel exceptionally solid, however, and that’s no surprise, coming from Shure. The company’s classic handheld dynamic mics have the reputation of being built solidly enough to drive nails, and that quality ethic continues into this line.
On the rear of the mic are two switches—an on-off attenuator (pad) switch and a three-position low-frequency roll-off switch. The pad attenuates the signal by 15 dB, facilitating the capture of substantially louder-than-normal sonic sources like drums, horns, or guitar amps at high SPL levels. The low-frequency roll-off switch has three positions—the first of which does not reduce low frequencies at all. The second position inserts an 18 dB/octave filter with a corner frequency of 80 Hz. This is most useful for eliminating subsonic rumbles and bumps associated with the mic’s stand, the floor, or rumble caused by wind or air conditioning noise. The third position inserts a 6 dB/octave filter with a corner frequency of 115 Hz, intended more to eliminate “mud” than super low thumps, bumps, and rumble. The mic’s grille employs three layers of mesh intended to reduce p-pops and other plosives, and there is also an internal shock mount to help reduce noise physically transferred into the mic’s case.
The mic is permanently fixed in a cardioid pattern, and I found the rejection to be very good. I’m always concerned with the potential for feedback with sensitive condenser mics onstage, and the directionality of this mic put my mind at ease. The mic’s diaphragm is one inch in diameter, 2.5µm thick, and layered with 24-karat gold. As with its KSM27 predecessor, the mic’s internal pre-amp is of transformerless Class A topology, a fact that impresses me. An additional subsonic filter in the electronics eliminates mechanical vibration below 17 Hz.
Shure publishes frequency response of 20 Hz – 20,000 Hz, exhibiting a relatively flat response throughout the spectrum, with a few notable exceptions. First, there is a small bump of about 1 dB centered just above 50 Hz—it’s quite broad, and not particularly pronounced, so it doesn’t cause much concern. Starting just below 3 kHz begins a rise that stays generally linear, increasing to about 2.5 dB at 5 kHz, at which point it sharpens, curving up to nearly 5 dB just below 7 kHz. It then turns back down to a boost of about 2 dB at around 8.5 kHz. It then gently slopes back up to about 3 dB at around 11 kHz. It remains there until about 15 kHz at which point it slopes downward—crossing 0 dB at about 18 kHz – down to -2 dB or so at 20 kHz. The pronounced bumps above 5 kHz are not troublesome in the least as long as the user is aware of them. If anything, they add “air” to the mic’s output, helping it to cut through the mix without extensive EQ. As a matter of fact, my friend Doug Robertson II, who is the technical director at Mountain Valley Church in Scottsdale, Ariz., said, “It reminds me of a [Shure SM] 57 that has been tweaked and EQ’d so it really sounds great.”
Output impedance is 150Ω, sensitivity is -37 dBV/Pa, and the mic can handle plenty of SPL (133 dB – 147 dB with pad on with a 1 kΩ load.) Signal-to-noise ratio is 84.5 dB, and dynamic range is 123 dB with a 1 kΩ load. Self-noise is a super-low 9.5 dB, a spec that really impressed me. Phantom power of 48V is necessary for operation. In the modern era, microphone manufacturers continue to improve these objective measurements for their mics, so the comparisons move into the subjective domain.
Shure recommends the mic for a broad variety of applications, including vocals, guitar amplifiers, horns, orchestras, choirs, drum overheads and percussion, acoustic instrument close-miking, low-frequency instruments, and room ambience miking. In the course of test-driving this mic, it was applied to a number of different situations that are common to church use. Specifically, this mic was test-driven on three different guitar amplifiers, male and female vocals, and as a drum overhead mic. In front of guitar amps, this microphone performed magnificently. In all three cases, a Shure SM57 was the original amp mic, replaced by the SM27. As one might imagine, the better resolution of the condenser made a substantial difference, but so did the higher-frequency bumps in the mic’s response curve. The result was guitars that cut through the mix without any EQ compensation and a better image of the guitar within the mix. Simply switching the one mic for the other made all the difference in the world.
Moving to vocals, I was not as impressed. Perhaps it’s because my brain compares the SM27 to other condenser mics that cost 10 times as much, but it just didn’t sound as good to me on vocals as it did on guitar amps. Specifically, it lacks the intimacy one expects from a condenser vocal mic, and I didn’t feel enough warmth or roundness from it. I would also say that to my ear, it’s a touch brittle in the high end. On the positive side, it very easily handled the SPL of vocalists really belting it out—no distortion whatsoever.
As a drum overhead mic, the SM27 performed very well. Shure SM81s are commonly used as overhead mics, and in this case, the 27 replaced the 81. The difference was night and day. Aside from the obvious performance improvements that come from a larger diaphragm, the drum kit simply sounded a lot more open and full with the 27 than the 81. And although I did not do so, I would not be afraid to put an SM27 on a tom, again due to it’s rock-solid construction, and because its side-address topology would facilitate keeping it back out of the normal range of the drummer’s sticks.
The Shure SM27 is a good microphone for use in worship, with the possible exception of vocal chores—I recommend to listen and judge with your own ears. The 15 dB pad allows the engineer to run the mic pres a little hotter, which can have a positive effect on tone. Used for guitar or drums, this mic is well worth your consideration.
Pros
Very solid construction – great for guitar amps and drum overheads – 15dB pad is nice
Cons
Not a first-choice vocal mic among large-diaphragm condensers
John McJunkin is the CEO of Avalon Podcasting in Chandler, Arizona, which offers high quality podcast production and consultation services to a broad range of clients. He’s also the host of the Podcast Pro Tech & Tips Podcast at www.avalonpodcasting.com.
