Cicada Audio FLX2500.1 — Ultra-High-Power 1-Channel Class-D Motorcycle Subwoofer Amplifier (2,500W RMS @ 2Ω)

Power Output — What the Numbers Mean

The FLX2500.1 is rated at 2,500W at 2Ω at 14.4V — a fully charged, engine-running system with a lithium battery supplying clean, stable voltage at load. A lithium battery is important here specifically because it maintains voltage closer to the 14.4V rated condition under the sustained current draw of a mono amp at high output, where a lead-acid battery would sag and reduce actual output below the rated figure.

No separate 4Ω rating is published for the FLX2500.1. For builds running a 4Ω subwoofer, the FLX1600.1 provides dual-impedance ratings and may be the more appropriate match depending on the driver specification.

Crossover and Signal Control

The FLX2500.1 runs HPF and LPF crossover modes with a fixed 12 dB per octave slope. The HPF range covers 10–80 Hz — used as a subsonic filter protecting the driver from excursion below its usable frequency range. The LPF range covers 80 Hz – 20 kHz, providing the main crossover point for sub and mid-bass channel integration.

The LPF extending to 20 kHz allows the FLX2500.1 to operate as a full-range mono amplifier when the LPF is not engaged — relevant for custom single-driver builds or high-output single-channel applications outside of dedicated subwoofer use.

A two-position input level switch matches the amp to its source — the high range (1.2V–12V) covers speaker-level output from the factory radio, the low range (0.25V–2.5V) covers pre-amp RCA from aftermarket head units or DSP pass-through line-level outputs.

Bass Control and Output Routing

A variable bass boost adds 0 to +12 dB at a centre frequency adjustable from 35 Hz to 90 Hz — the boost is tuned to where the enclosure actually needs it, not fixed at an arbitrary point. On the road: a sealed saddlebag enclosure that rolls off early can be lifted exactly at its knee frequency, without dragging up content below the driver's usable range.

A wired remote bass level control port accepts Cicada's remote subwoofer level controller, giving up to 20 dB of adjustment from the riding position. It attenuates the signal rather than boosting it — turning it down adds no gain-stage noise, and full-up simply returns to the level set at the amp. On the road: bass drops for a conversation at the servo and comes back at highway speed without opening the fairing or bag.

A full-range pass-through output duplicates the input signal at line level for a second amplifier with no signal loss — daisy-chain a 4-channel amp or a second mono amp without Y-leads or a distribution block in the signal path.

A two-position input level switch matches the amp to its source: the high range (1.2V–12V) for speaker-level output from a factory radio or head unit, the low range (0.25V–2.5V) for pre-amp RCA from an aftermarket head unit or DSP pass-through.

Built for the Motorcycle Environment

The circuit board is conformal coated — a protective film sealing the electronics against moisture, humidity, and vibration-borne dust — and the amplifier is encased in an extruded aluminium heatsink with a top-mounted cooling fan moving air through the chassis under sustained load. On the road: a mono amp working a subwoofer at highway volume runs hot by design — the fan and heatsink keep it inside its thermal envelope in a closed bag or Tour-Pak position.

Protection and status are handled by three indicators: a power LED, a protect LED that lights when thermal protection engages or a fault such as a damaged speaker or shorted wire is detected, and a dedicated clip LED that should only flash on musical peaks. If the clip LED holds solid for more than 2–3 seconds, back the volume or gain off. On the road: gain setting and fault-finding by eye — a shorted speaker wire or an overheating amp announces itself before it becomes a failure.

The crossover, gain, and bass boost potentiometers are detented — they click through fixed positions rather than sweeping freely, so settings are exact, repeatable, and immune to vibration drift. On the road: the tune set in the workshop is still the tune after a corrugated highway.

Power and ground run through busbar-style terminals, with heavy-duty screw-down speaker terminals — no crimped pins to work loose under vibration.

Mounting Options

Every FLX amplifier ships with two sets of mounting brackets: standard brackets (preinstalled) for flat-surface mounting, and inverted brackets that mount the amp top-face down — keeping the cooling fan on fan-equipped models facing downward with proper airflow clearance. The brackets carry multiple mounting points and can be trimmed or modified to suit a specific fairing, amp rack, or bag install without compromising structural integrity. Where there is no surface to screw into, the included 3M® locking velcro, zip ties, or straps secure the chassis directly. For 2024+ Road Glide® and Street Glide®, the model-specific 24HDAR-RG and 24HDAR-SG single-amplifier mounting systems bolt an FLX amp into the fairing without custom fabrication. On the road: the amp adapts to the space the bike actually has — factory amp tray, amp rack, or a tight custom cavity — rather than dictating it.

System Integration

The FLX2500.1 accepts high-level speaker output from the factory Harley Boom! Box radio directly — no additional converter required for 2014–2023 models — or low-level RCA from any aftermarket head unit or DSP pass-through output.

Turn-on supports REM and DC offset modes. At 80A music-level current draw, the FLX2500.1 requires a lithium battery to sustain clean output at volume. Maximum draw is 260A; a 150A fuse is required on the power feed. For dual-amp installs adding the FLX2500.1 alongside a 4-channel amp, calculate total system current draw against the charging system's output before finalising the design.

Wiring matters at these current levels: use properly sized OFC (oxygen-free copper) power and ground wire only — never CCAW (copper-clad aluminium), which carries less current for the same gauge and heats under sustained draw — and locate the main fuse within 457 mm (18") of the battery terminal.

2024+ Platform Notes

For 2023.5 CVO and 2024+ Harley-Davidson Touring models running Skyline OS, the FLX2500.1 can be integrated as part of an aftermarket audio system when paired with a NAV-TV ZEN-H or ZEN-H Pro upstream in the signal chain. Without a ZEN-H or ZEN-H Pro, integration with a 2023.5 CVO or 2024+ Harley is not supported. For 2014–2023 models (excluding 2023.5 CVO), the high-level input connects directly to the factory Boom! Box radio.

Fitment

• Harley-Davidson Street Glide: Fairing amp tray or custom enclosure position.
• Harley-Davidson Road Glide: Fairing amp tray or custom enclosure position.
• Harley-Davidson Ultra Limited / Ultra Classic: Fairing amp rack or Tour-Pak position.
• Harley-Davidson CVO models: Fairing amp rack or Tour-Pak position (see 2024+ note above for Skyline OS bikes).
• Harley-Davidson Trike: Compatible — fairing, trunk, or saddlebag amp rack positions.
• Compatible with OEM Boom! Box radios (high-level input), all aftermarket head units (high-level or RCA), and DSP pass-through line-level outputs.
• Requires lithium battery upgrade and 2 AWG power and ground wiring.

Technical Specifications