Sennheiser MZA 900 P-4

Sennheiser MZA 900 P-4 Phantom Power Adapter

The Sennheiser MZA 900 P-4 (Article Number: 500226) is a professional, high-performance active inline phantom power adapter. It is engineered to connect pre-polarized electret condenser microphones—specifically those configured with a special 3-pin connector (LEMO-compatible SE pinout)—directly to standard, balanced studio and live sound equipment that provides regular 12V to 48V phantom power.

The "P-4" designation specifies its factory input jack configuration: a specialized 3-pin lockable socket. This makes it an essential utility tool for adapting high-end lavalier and headset microphones (like the MKE 1, MKE 2-4, and HSP 4) away from their usual wireless bodypack transmitters and converting them into wired, balanced XLR microphones.

Key Operational and Engineering Attributes

• Active Signal & Impedance Conversion: The internal circuitry steps down high-voltage studio phantom power (12V - 48V) to the lower bias voltage required by miniature capsule elements. Simultaneously, it transforms the high-impedance unbalanced capsule signal into a low-impedance, fully balanced audio stream.

• Switchable Acoustic Tailoring (Bass Roll-Off & Pad): Outfitted with a three-position mechanical micro-slide switch located on its side. It allows sound technicians to run the adapter completely flat, apply a targeted low-cut filter to combat low-frequency stage rumble or wind noise, or engage a -12 dB attenuation pad to prevent capsule overload from high-SPL sound sources.

• Military-Grade RF and Structural Shielding: Housed in a rugged, impact-resistant solid metal chassis. It acts as a complete Faraday cage, shielding the sensitive, unamplified microphone signal against radio frequency interference (RFI) emitted by smartphones, stage lighting dimmers, and wireless intercom systems.

• Integrated Hardware Monitoring LED: Features an integrated, multi-color micro-LED indicator on the front panel. It lights up solid green when stable phantom power is being received from the mixing console or audio interface, providing immediate visual troubleshooting on dark stage layouts.

Technical Specifications Matrix

In the Box: Production Component Inventory

• 1 x Sennheiser MZA 900 P-4 Active Phantom Power Adapter

• 1 x Integrated Heavy-Duty Steel Belt Clip

• 1 x Instruction & Calibration Manual

Field Configuration and Application Advice

Configuring the Filter Switch Elements: To customize the adapter's performance for your specific environment, locate the micro-slide switch on the side of the metal barrel.

• Position 1 (Straight Line): Provides a completely flat, full-bandwidth tracking signal—ideal for studio recordings and capturing quiet instruments.

• Position 2 (Bent Line): Engages the 125 Hz roll-off filter to instantly clean up low-end room rumble or clothing friction.

• Position 3 (-12 dB): Attenuates the incoming signal before it hits your mic preamp—perfect for high-energy theatrical performances or close-miking loud sound sources.

Proper Cable Management and Connection Order: When integrating this adapter into a production chain, always plug your miniature 3-pin microphone cable securely into the locking socket of the MZA 900 P-4 before sending 48V phantom power down the main XLR line from your mixing console. Connecting or disconnecting the delicate 3-pin microphone head while the circuit is actively powered can cause loud electrical pops and subject the capsule to brief voltage spikes that may degrade the element over time.