Cicada Audio WX900.4 – Waterproof 4-Channel Amplifier (225W x4 @ 2Ω)

Power Output – What the Numbers Mean

All output figures are rated at 14.4V, the voltage of a charged, engine-running system. The WX900.4 produces 225W × 4 at 2Ω, which is where its name comes from: four channels at 225W is 900W total RMS. At 4Ω each channel makes 200W. The drop from 2Ω to 4Ω is smaller than on many amplifiers, which suits builds running 4Ω speakers in four-channel mode.

Bridged, channels pair up to deliver 450W × 2 into 4Ω. Each bridged pair presents half the load to each of its two channels, so a 4Ω speaker on a bridged output works those channels as if they were driving 2Ω. That is why the bridged rating is given at 4Ω only. Do not bridge the WX900.4 into a 2Ω load.

Why IPX6

IP ratings are defined by the IEC 60529 standard, and the second digit covers water. IPX6 means the enclosure is protected against powerful water jets from any direction. The test uses a 12.5mm nozzle delivering 100 litres per minute from about 3 metres. That covers heavy rain at speed, road spray thrown up from a wet highway, and hosing the bike down. IPX6 is not a submersion rating; immersion is covered by IPX7 and IPX8. A high-pressure washer held close to the amp also goes beyond what the IPX6 test applies. On the road: the amp is protected against the water a riding day actually throws at it, and the rating tells you where its limits are.

The rating depends on how the amp is built. The circuit board carries a protective conformal coating, a film that seals the electronics against moisture and condensation. The whole assembly is fully encased in an extruded aluminium heatsink enclosure, and every lead leaves the chassis through over-moulded strain relief made from water-repellent materials. On the road: humidity and temperature swings create condensation inside an enclosure, and a coated board is protected from that even when no rain is falling.

Sealed Connections

On a conventional amplifier, power, ground and speaker wires are landed in screw or busbar terminals. The WX900.4 replaces them with factory-moulded, over-braided leads: 305mm (12") of 8 AWG for power and ground, and 152mm (6") of 16 AWG for the speaker outputs, terminated in a female Molex® connector. The strain relief is moulded onto the chassis, so vibration flexes the lead rather than the joint. On the road: loose or corroded terminals are a common source of intermittent amp faults, and here the joint is sealed and supported before the amp leaves the factory.

Signal comes in through Micro DIN inputs, which accept RCA or H-D custom-terminated input harnesses. The WX900.4 takes high-level (speaker-level) input directly from a factory radio, so on pre-Skyline bikes no line-output converter is needed, as well as low-level RCA from an aftermarket head unit or processor.

Heat and Efficiency

The WX900.4 runs an IR-based Class-D chipset with 80% total efficiency. That means roughly a fifth of the power it draws becomes heat rather than sound. A sealed enclosure can't vent that heat, so the extruded aluminium body does the cooling, conducting it out through the chassis. On the road: high efficiency keeps the heat load small enough for a sealed chassis to manage in a closed fairing on a hot day, and it means less current drawn from the charging system for the same output.

The ICAD protection circuit guards the output stage against overload. Two LED indicators, one for clipping and one for status, make gain setting and fault-finding a visual job.

Tuning and Signal Control

A selectable crossover offers LPF, Full Range or HPF from 30Hz to 300Hz with a 12dB-per-octave slope. That covers high-passing fairing speakers so they aren't asked to reproduce deep bass at volume, low-passing a channel pair for mid-bass, or running coaxials full range. Input sensitivity and gain both adjust across 12V to 0.2V, wide enough to match a factory radio's speaker-level output or a head unit's RCA pre-out. The 2/4 channel input switch routes a single stereo input to all four channels.

Turn-on can be triggered by REM (remote wire), DC offset or VOX (audio signal-sensing). On the road: fewer wires to route through the fairing, and a choice of method to suit the head unit or interface feeding the amp.

Power Supply and Wiring

The WX900.4 operates from 9V to 16V. Current draw is 60A at music levels and 110A at maximum, and Cicada recommends an 80A fuse on the power feed. At these current levels the amp is a substantial load on a motorcycle charging system, so check the total draw against your bike's charging output before adding further amplifiers or high-draw accessories. Use oxygen-free copper (OFC) power and ground wire of the correct gauge, and fuse the feed close to the battery.

System Integration

The WX900.4 has no onboard DSP. Where a build needs time alignment, multi-band EQ or advanced routing, place a processor such as the DSP412PRO upstream of the amp, or choose the WX1200.4PRO.

On 2023.5 CVO™ and 2024+ Touring models running Skyline OS, factory audio is carried digitally over A2B. The amplifier takes its signal from an A2B interface such as the NAV-TV ZEN-H or ZEN-H PRO, which is required for these bikes.

Mounting

The included mounting brackets allow the amp to be installed in more than one orientation, so it can suit the space available. The WX900.4 is also designed for a secure, factory-style fit on Cicada Audio amplifier racks, which are sold separately. Ask us which rack suits your bike. On the road: a rack-mounted amp stays where it was put, and on the right rack there is no custom fabrication to do.

Technical Specifications

In the Box

• Cicada Audio WX900.4 amplifier with moulded power, ground and speaker leads
• Mounting brackets