Shure KSM44
MULTIPATTERN CONDENSER MIC

by Michael Cooper
  The KSM44 multipattern condenser mic is the second offering in Shure’s KSM microphone line. It follows on the heels of the cardioid-only KSM32, which was introduced a couple of years ago. Shure’s intent was to optimize the KSM44’s frequency response for vocal tracking, though the mic is well-suited for a variety of other applications.
Shure KSM44

Shure KSM44 (click for larger image)
Considering its $1,340 list price, the solid-state KSM44 boasts a surprisingly extensive feature set. Its three polar patterns—cardioid, omni and bidirectional—are selected by a switch on the front of the mic body. A 15dB pre-attenuation switch and a three-position low-frequency response switch are found on the rear of the mic. Looking beyond these obvious external attributes, however, it becomes clear that rigorous attention to detail went into the design and production of this microphone.

The side address KSM44 employs dual, 1-inch diameter, mylar diaphragms that are only 2.5 microns thick and are layered with 24-carat gold via a vapor deposition process. The Class-A, discrete, transformerless preamplifier helps the KSM44 achieve maximum SPLs of up to 151 dB with the pre-attenuator switched in and the mic in Omni mode. Self-noise is rated at a mere 7 dBA, and sensitivity is a hefty 28 mv/PA in Cardioid mode, foretelling tracks with a rock-bottom noise floor. Omni and Bidirectional modes offer a considerably more modest (yet respectable) 14 to 16 mv/PA output and a still hushed 10dBA self-noise spec.

The externally biased capsule works best with phantom powering in the 44 to 52VDC range, but can tolerate juice as low as 11 VDC with only slightly decreased headroom and sensitivity. The KSM44 is something of a current hog, typically draining 5.4 mA at 48 VDC. Unless you have a really wimpy phantom power supply and use many modern mics simultaneously, the 44’s current drain will not pose a problem.

The KSM44’s frequency response in Cardioid mode exhibits a smooth boost between 2 and 8 kHz (culminating in a 3dB boost at 6 kHz) and a still milder bump centered on 11 kHz. Response falls off fairly rapidly above approximately 13 kHz, ending 5 dB down at 20 kHz. At a 6-inch distance from the mic, the proximity effect causes a gradual rise below 600 Hz, reaching a maximum +5dB boost at 50 Hz.

Omni mode is virtually ruler-flat up to 9 kHz, rises +4 dB to 11 kHz, and then it drops off in similar fashion to the Cardioid mode response. The response in Bidirectional mode is fairly typical of a pressure-gradient, large-diaphragm condenser, with a more dramatic boost in the lower highs compared to that produced by Cardioid mode, twice the bass proximity effect and a gradual roll-off above 9 kHz.

Shure took several measures to reduce the KSM44’s sensitivity to vocal plosives and to allow creative tailoring of the mic’s low- frequency response. The aforementioned low-frequency response switch offers three passive EQ curves: flat (no bass roll-off), a steep 18dB per octave roll-off below 80 Hz, and a milder 6dB per octave roll-off below 115 Hz. The mic also features a fixed subsonic filter to eliminate rumble and structure-borne noise below 17 Hz. An internal shock-mount complements the ShureLock™ elastic-suspension shock-mount included with the mic (more on the shock-mount below). The head grille is a three-stage affair, featuring a nylon cloth layer inside two layers of hardened, low-carbon steel. The grille is somewhat unusual in that the outermost grid offers far smaller apertures than the layer beneath, a choice made for cosmetic purposes.




Reprinted with permission from Magazine, February, 2001
© 2000, Intertec Publishing, A Primedia Company All Rights Reserved


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