Sennheiser MZA 900 P Phantom Power Adapter

Sennheiser MZA 900 P Phantom Power Adapter

The Sennheiser MZA 900 P is an in-line phantom power adapter and preamplifier that lets Sennheiser condenser microphones fitted with a 3.5 mm locking connector work into a standard balanced XLR microphone input. Microphones from Sennheiser’s evolution wireless family are designed to run from the low bias voltage of a bodypack transmitter; a mixing console, recorder or interface expects a balanced XLR source powered by phantom power instead. The MZA 900 P sits between the two worlds. It takes phantom power in the P12 to P48 range from the XLR side, supplies the microphone with the power and impedance conditions it was designed for, and returns a balanced, line-ready microphone signal on its XLR-3 male output.

Sennheiser positions the adapter for its evolution wireless miniature and instrument microphones and for MKH 8000 series applications, and it is the adapter supplied with microphones such as the e 908 B and e 908 D clip-on condensers. For engineers who already own those microphones for wireless work, the MZA 900 P is what makes the same capsule usable on a wired channel when radio conditions, venue rules or a recording session call for a cable instead of a transmitter.

Key features

• Phantom power conversion: Runs on P12 to P48 phantom power from any standard XLR microphone input and powers the connected Sennheiser condenser microphone correctly.
• Locking 3.5 mm input: Input socket is a lockable 3.5 mm jack that holds evolution wireless style microphone connectors securely against tugs and movement.
• Switchable pre-attenuation: A 0 dB / -12 dB pre-attenuation switch protects the input stage when loud sources would otherwise overload the chain.
• Switchable roll-off filter: Low-frequency roll-off at 125 Hz (-3 dB, 12 dB per octave) reduces rumble, handling noise and proximity build-up at the source.
• Flat, wide response: Frequency response of 20 Hz to 20,000 Hz within -1 dB, so the adapter does not colour the microphone it feeds.
• Balanced XLR-3 output: Standard XLR-3 male connector with 100 ohm output impedance plugs straight into consoles, interfaces, stage boxes and recorders.
• Cable tester function: The adapter can also be used to check microphone cables, following the procedure in Sennheiser’s instructions for use.

Signal handling in detail

The two switches are what separate the MZA 900 P from a simple wiring adapter. Pre-attenuation of -12 dB, engaged before a loud source such as a brass instrument or a close-miked drum, keeps the adapter’s own electronics and the following preamp out of overload; maximum output voltage is specified at 1.8 V on P48 with 0 dB attenuation. The roll-off filter addresses the opposite end of the spectrum, trimming low-frequency energy below the useful range of most miniature microphones, which is where stage rumble, footfall and handling noise live. Output noise is low, specified at 3 microvolts A-weighted, so the adapter adds nothing audible to a quiet recording chain. Minimum load impedance is 5 kohms at 0 dB attenuation and 2 kohms at -12 dB, comfortably within what normal microphone inputs present.

Build and handling

The housing is a compact barrel 100 mm long, tapering between 19 mm and 22 mm in diameter, shaped to sit in line with the microphone cable rather than in a rack or on a shelf. A clothing clip arrangement covered in Sennheiser’s instructions lets the adapter be secured to clothing or a belt when it is used with a lavalier or headset microphone on a wired lead, keeping its small weight off the microphone itself. Because it draws its power entirely from the phantom supply at the XLR end (current consumption is in the region of 2.6 to 2.8 mA), there are no batteries to manage and nothing to switch on: connect the microphone, connect the XLR cable, apply phantom power and the chain is live.

Where it is used

Typical uses are theatre and broadcast work where a lavalier or headset microphone from a wireless kit needs to appear on a wired backup channel, studio and location recording with e 908 instrument microphones on saxophone, brass or percussion, and installed sound where a Sennheiser miniature condenser is specified but radio is not wanted. It is also the practical way to audition, measure or record from an evolution wireless microphone in a workshop or studio without setting up a transmitter and receiver at all.

Small as it is, the MZA 900 P is a purpose-built piece of Sennheiser engineering rather than a generic converter: correct powering, switchable protection against overload and rumble, and a balanced output that behaves exactly as the following input expects. For anyone working with Sennheiser’s miniature condensers in both wireless and wired contexts, it is the link that keeps one microphone inventory useful in both.