A-FILTER RF Filter for Balanced Microphones

The A-FILTER for Balanced Microphones adds RF immunity for microphones, specifically when connected to digital wireless transmitters like the A10-TX.

The instructions below describe how to mount the A-FILTER for Balanced Microphones into a female XLR connector.

Before starting please make note of the following:

  • The A-FILTER should be placed as close to the microphone as possible. The benefit of the RF filter is significantly reduced if placed downstream of the microphone connector.
  • Make certain to use high-quality XLR connectors. Inexpensive connectors, including many painted XLR connectors, do not provide adequate electrical contact between the connector shell and the microphone connector.
  • The A-FILTER does not degrade the audio signal, affect phantom voltage, or draw any power in any way.

Supplies Required

  • The A-FILTER RF Filter for Balanced Microphone.
  • High quality female XLR connector. The circuit board was designed with Neutrik NC3FX connectors.
    AC-BALXLR (blue cap) is not compatible with the A-FILTER. AC-BALXLR-2 (black cap) already has the A-FILTER installed.
  • Solder and tools for cable assembly.

Note: Installing the A-FILTER assumes knowledge of proper cable soldering and termination.

Step 1

Disconnect the XLR female connector and cleanly unsolder the existing cable from the insert. If this is a new cable assembly, this step is not necessary.

Step 2

Solder the A-FILTER circuit board to the cable. Take note of the polarity labeled on the circuit board. Solder the ground connection to the square thru-hole pad.

Step 3

Solder the A-FILTER circuit board to the connector insert. Make certain to align the connector pins with the labeled solder pads on the board.

Connect pin-1 of the connector to the insert’s shell tab.

Step 4

Carefully slide the chuck over the A-FILTER circuit board.

Step 5

Place the connector housing and finish the installation by sliding the bushing to the housing and turning to secure.

Step 6

Test the cable for continuity.

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