AKG PZM10 Hemispherical Flush-Mount Boundary Layer Microphone XLR

AKG PZM10: An Invisible Table, Wall or Ceiling Microphone

The AKG PZM10 is a hemispherical Pressure Zone Microphone designed to be flush mounted through a single 25/32 in (19.8 mm) hole in a table, wall or ceiling, leaving almost nothing on show. Its published response runs from 80 Hz to 20,000 Hz with a sensitivity of 2.5 mV/Pa at microphone level, a 240 ohm balanced output and 26 dB-A equivalent noise, and it terminates in a 3-pin XLR male fed by 12 to 48 V phantom power. AKG positions it for security, surveillance and conference-table use, three applications that share one requirement: the microphone must not be noticeable. Where a visible microphone would change how people behave, this is the pickup that does not.

Pressure Zone Operation, Explained From First Principles

A Pressure Zone Microphone places a small condenser capsule extremely close to a sound-reflecting boundary, and that placement changes what the capsule hears. Within a very small fraction of a wavelength of a hard surface, the incoming wave and its reflection are effectively coincident, so instead of arriving at different times and cancelling each other at certain frequencies they add together in phase across the whole band. Physically the microphone is also now looking into a half-space rather than a full sphere, which is what gives it a hemispherical pattern and a useful lift in sensitivity. For an installer the practical consequence is that the mounting surface is part of the microphone: a stiff, nonabsorbent table or ceiling panel is doing acoustic work, while a thin, flexible or heavily upholstered surface will not.

A 25/32 Inch Hole and Nothing Else

Installation is the strongest argument for this particular model. A single 25/32 in (19.8 mm) hole accepts the body, which measures roughly 2.8 in (72 mm) deep behind the surface with a 1.5 in (39 mm) diameter face, so all that remains visible in a boardroom table or a wall panel is a small disc that reads as a fitting rather than as a microphone. That matters in an interview room, a custody suite or a retail counter where an obvious microphone would alter the conversation, and it matters just as much in a designed boardroom where a client has rejected anything sitting on the table surface. Because the whole assembly sits inside the furniture or the ceiling void, there is nothing to knock over, nothing to steal and nothing to coil away at the end of a meeting.

Response Shaping Aimed at Speech in a Noisy Building

Frequency response here is deliberately not flat, and the reason is practical. AKG rolls off the low frequencies below the voice range and lifts the high frequencies slightly, which strips out the air-handling rumble, structural noise and traffic energy that dominate the bottom of the spectrum in an occupied building while adding a little clarity where consonants live. In a security or surveillance application that shaping is the difference between a recording where a conversation can be understood and one buried under an air-conditioning diffuser two feet away. Conference use benefits in the same way, since a hemispherical microphone in a table hears the room as well as the talkers and every decibel of low-frequency noise it declines to pass is headroom kept for speech.

Electrical Interface and System Wiring

Connection follows normal professional practice, which keeps this microphone easy to design into a system. Phantom power of 12 to 48 V is applied as positive voltage on pins 2 and 3 with respect to pin 1, the standard arrangement on any console, stage box, recorder or digital signal processor with phantom capability, and no local power is required at the microphone. Output is 240 ohms balanced at microphone level, AKG recommends a 2,000 ohm load and the manual specifies 1,000 ohms as the minimum, so ordinary preamplifier inputs are comfortably suitable. Because the microphone terminates in a 3-pin XLR male, the run back to the rack is standard balanced microphone cable and can travel building distances without special treatment.

Where the PZM10 Is Specified

Typical installations divide into two groups with the same underlying need. Security and surveillance work puts these in retail counters, banking halls, teller windows, interview rooms and custody suites, where the microphone feeds a recorder or logging system and must be tamper-resistant and unremarkable. Conference and teleconferencing work puts them in boardroom tables, hearing-room benches and ceiling positions, where an architect or client has ruled out visible microphones and a hemispherical pattern forgives the fact that nobody sits where the drawing said they would. Anyone choosing between this and the line-level version should note the difference: this model delivers microphone level on an XLR, while the PZM10 LL delivers line level on an unterminated cable.