AKG PZM11 LL WR Weather-Resistant Line-Level Boundary Layer Microphone

AKG PZM11 LL WR: Outdoor Speech Pickup That Survives the Weather

The AKG PZM11 LL WR is a weather-resistant hemispherical Pressure Zone Microphone with a line-level output, built for drive-through order points, outdoor intercoms, toll booths, SOS telephones and theme-park security positions. WR designates the weather-resistant construction and LL the line-level output, and both are load-bearing: an internal plastic membrane protects the capsule from water damage, while an open-circuit sensitivity of 1.4 V/Pa typical lets the microphone feed a recorder or video system with no microphone preamplifier in front of it. Powering is 12 to 24 V AC or DC at 4 milliamperes, and the published bandwidth of 80 Hz to 10,000 Hz is deliberately narrower than the indoor models in this family. Every one of those choices exists because outdoor speech is a different problem from indoor speech.

How the Weather Protection Works, and Its Limits

Water and condenser capsules are fundamentally incompatible, so the protection here is physical rather than electronic. AKG fits a plastic membrane inside the microphone that stands between the outside air and the capsule, blocking liquid water while remaining thin enough to pass the acoustic pressure the capsule needs to hear, which is why the microphone is specified to operate during rainfall rather than merely to survive it. Two limits are published and both are worth respecting: direct high-pressure spray aimed at the microphone may damage that membrane, so this is not a part to point a jet washer at during a forecourt clean; and if ice forms on the microphone the frequency response changes temporarily, returning to normal once it has dried out. Understanding those boundaries is what separates an installation that lasts a decade from one that needs a service call after the first hard winter.

Why 80 Hz to 10,000 Hz Is the Right Answer Outdoors

Narrowing the bandwidth looks like a compromise and is in fact a deliberate intelligibility decision. Outdoors, the low end of the spectrum is dominated by traffic, wind, engine idle and mechanical plant, none of which carries any speech information, and the extreme top end contributes little to consonant recognition while readily picking up tyre noise and rain impact. Restricting the response to the band that actually carries voice, then rolling off the bottom and lifting the top slightly for clarity, delivers a cleaner result at a drive-through window than a wider-band microphone would; the operator inside hears words rather than weather. That shaping is why the WR model's published figures differ from the indoor PZM11 and PZM11 LL, whose responses extend to 20,000 Hz on a 12 to 48 V phantom supply, and why the two sets of numbers must never be interchanged.

Line Level at 1.4 Volts per Pascal

Output level here is exceptional for a boundary microphone and it exists for a specific reason. An open-circuit sensitivity of 1.4 V/Pa typical, with a power sensitivity of +8 dBm/Pa, means the microphone is already producing a line-level signal at the plate, so it can be wired straight into the line input of a drive-through intercom head end, a video recorder or a building controller with no preamplifier and no gain structure to design. Its source impedance of 75 ohms balanced into a recommended minimum load of 1,000 ohms is unusually low, which makes the signal robust over the long external cable runs these applications demand, and the output can be taken balanced or unbalanced depending on what the head end offers. Maximum SPL is quoted as 100 dB SPL for 3 percent THD at maximum gain, which is consistent with a device intended for speech at conversational distance rather than for close music work.

Mounting, Wiring and Commissioning

Physical installation follows the same trade-friendly logic as the rest of the family. A standard electrical outlet box of at least 2 in (51 mm) depth accepts the plate, which measures 4.5 x 2.8 x 1.7 in (115 x 70 x 44 mm) in a silver gray finish, and AKG supplies the fixing screws in the box. Field wiring lands on screw terminals clearly marked AUDIO+, AUDIO- and GROUND, so a contractor working at a lane bollard or a wall station has no soldering to do and no connector to weatherproof. Because the supply can be 12 to 24 volts of either AC or DC at only 4 milliamperes, existing intercom, gate-controller or door-station power is very often already present at the box, which removes a separate power run from the job entirely.

Where the PZM11 LL WR Is Installed

Quick-service restaurant drive-throughs are the archetypal application, with the microphone in a menu-board station taking orders through rain, wind and engine noise while the crew inside hears a line-level feed. Toll booths, parking-garage entry lanes, bridge and tunnel call points, SOS and emergency telephones, campus help points and theme-park security positions all present the same combination of outdoor exposure, long cable runs and a head end with line inputs. Building and home automation installers use them as outdoor listening points for the same reasons. Anywhere a conversation has to be captured outdoors and delivered to equipment that never expected a microphone, this is the model designed for the job.