Radial Catapult RX4

You can use venue cabling if it provides a dedicated link between compatible modules. TX4 and RX4 carry four balanced analog signals over Cat 5 or Cat 6; the RX4 is passive and does not convert audio to Dante or another Ethernet protocol. A network switch cannot replace the cable connection between the modules.

The eight XLR connectors on the RX4 are two parallel sets of the same four signals. They do not add four channels or provide transformer isolation. Variants such as RX4M and RX4L provide isolation for different applications.

1. Identify the module at the other end and every cable segment. An RX4 on its own does not establish what is connected at the stage end. Before using venue wiring, confirm the route through sockets and patch panels: keep it separate from network equipment and PoE.
2. Compare the model, pinout and documentation at both ends. An RJ45 or etherCON connector fitting the socket does not prove that channels match. The table on this page reproduces the official TX4/RX4 pinout; it does not validate an adapter from another manufacturer.
3. With the PA and monitors muted, first test both modules using a short, known-good cable. Then add the long cable or venue wiring, checking each channel. If the short link works and the longer route does not, investigate that wiring before replacing the RX4. For a return from the console, use its line output. An amplifier’s power output requires speaker cable and must not be connected to this path.

If 48 V comes from the console through the RX4, check shield continuity through the Cat cable and connectors, as well as the LIFT setting. Radial requires shielded cable to carry phantom power. A cable that passes line-level audio has not necessarily completed the phantom-power path.

The manufacturer’s FAQ explains that LIFT disconnects the shield at the RJ45 and interrupts phantom power supplied by a distant console through the RX. Phantom supplied at the TX end can still power the microphone. Lifting the shield does not turn the RX4 into a transformer-isolated splitter.

1. Draw the path from the 48 V supply to the microphone or DI. Check that the source needs phantom power, and consult each destination’s manual when splitting to two consoles. Agree which console will supply power.
2. Before repatching, turn levels down as Radial instructs and switch phantom off using the console’s procedure. Test the cable and shield with a suitable tester while disconnected from the equipment; never perform a continuity test on a powered circuit.
3. For the direct link, start with LIFT in the out position specified in the manual. Compare a known-good shielded cable with the suspect segment and note when audio returns. If a dynamic microphone works but a condenser does not, continue checking power, the microphone and cable; that observation alone does not identify the fault.
4. If there is hum, establish how it relates to the patch before trying LIFT. Keep equipment protective earth connected: this control acts on the audio shield. If isolation is needed, identify the module and its direct/ISO outputs; the RX4 has no transformers.

Start with one source at a time and check the channel number at both ends. Four signals share the Cat cable, but each uses a different pair. Losing all four suggests checking the shared cable path; it does not prove that path is faulty. If only one signal fails, also compare its XLR leads and destination channel.

Label modules and channels clearly when distributing boxes across the stage. Radial recommends grouping signals of similar level: a strong line-level signal alongside a low-level microphone can cause crosstalk. Check for this during rehearsal.

1. Label each module, Cat cable and XLR patch with its stage area and channels 1–4. Both RX4 XLR sets repeat those signals: a second destination should receive the same assigned channel, with levels and phantom power planned.
2. Send an agreed spoken phrase or test tone to CH1 only and listen to CH1–4 separately at the destination, at low level. Repeat for each input and both output sets. Record the expected channel, the channel heard, any noise and the change made.
3. If the signal appears on another input, compare the pinout and patch. If it is missing, substitute one known-good segment at a time: input XLR, Cat cable, output XLR and console input. Record the result rather than replacing the entire chain at once.
4. For a route carrying mic and line signals, keep the microphone source silent and run the line source at its operating level to listen for leakage. If it occurs, separate signal levels onto different routes and repeat the test. Prepare spare cables and modules, plus an XLR bypass for critical signals; rehearse the recovery path too.