Cicada Audio FLX700.4 — Full-Range 4-Channel Class-D Motorcycle Amplifier (700W RMS / 175W x4 @ 2Ω)
| Channels | 4 Channel |
| Power | 4x175W RMS |
| Year Range | 1998-2013, 2014-2023, 2024+ |
Factory Harley audio runs out of headroom before you leave the suburbs.
The Cicada Audio FLX700.4 is a full-range 4-channel Class-D amplifier purpose-built for motorcycle audio — compact enough to fit standard Harley-Davidson Touring fairing amp trays, capable of delivering 175W × 4 RMS at 2Ω, and carrying the full 20 Hz – 20 kHz crossover range with 48 dB per octave slope control for any speaker stage configuration. The most versatile amplifier in the FLX range.
Most factory Harley audio systems are engineered to a price point, not a performance target. They clip at highway speeds, roll off in the midrange where clarity matters most, and have no meaningful headroom for demanding speakers. At 100 km/h with wind and pipes, that gap becomes obvious immediately. A conventional car amplifier is not the answer — wrong chassis size, not weather-rated, and the current draw stresses a motorcycle's charging system. The FLX700.4 solves all three problems.
Who This Is For
For riders who want a properly powered Harley audio system — not the minimum improvement, but the correct amplifier that drives quality speakers at highway speed without clipping. The FLX700.4 is the step up from the FLX500.4 (same crossover, 40% more output per channel) and the crossover-architecture choice when driving multi-way component speaker stages. For builds that need substantially more per-channel output, the FLX1000.4 is the next step at the same compact footprint.
What This Is Best For
- Upgrading a factory Harley Boom! Box system without replacing the head unit — high-level inputs connect directly, VOX/DC offset turn-on handles remote wire issues on OEM platforms. No signal processor required to integrate.
- Running a 4-speaker front and rear fairing stage on a Street Glide or Road Glide where amp space is tight — 175W × 4 at 2Ω from a chassis that fits standard Harley fairing amp trays.
- Multi-way component builds requiring full crossover control — the 20 Hz – 20 kHz crossover range with 48 dB per octave slopes provides clean driver separation between dedicated horn tweeters and midrange drivers, keeping the front stage coherent at highway speed.
- Bridged rear channels for a compact subwoofer or mid-bass enclosure — 350W × 2 at 4Ω bridged provides genuine headroom for a sealed mid-bass driver in a saddlebag or Tour-Pak position.
- Builds where charging system load matters — at 50A music-level draw, the FLX700.4 stays within factory Harley alternator capacity on most Touring models. No alternator upgrade required.
- Intermediate builds that will add DSP later — the FLX700.4 can be retained in the signal chain when a processor is added upstream. Buy the amplifier now, add the DSP when the build progresses.
The Bottom Line
The most versatile amplifier in the FLX range — 175W × 4 RMS at 2Ω, the widest crossover control, and a chassis that fits any standard Harley Touring amp tray. If the build needs real amplifier power without a high-output electrical upgrade, this is the correct starting point.
Ready to upgrade? Add to cart above. For more per-channel output, the FLX1000.4 delivers 254W × 4 at 2Ω in the next chassis size up. For a more modest build, the FLX500.4 offers 125W × 4 at the same footprint.
Power Output — What the Numbers Mean
The FLX700.4 delivers 120W × 4 RMS at 4Ω and 175W × 4 RMS at 2Ω — 700W total RMS at rated voltage (14.4V DC). That is the figure that matters for motorcycle builds where 2Ω pro-audio speakers are standard. The 2Ω figure represents real usable power, not inflated peak numbers.
Bridged, the amp produces 350W × 2 at 4Ω — the configuration for a two-speaker front stage that needs high output per channel, or for driving a compact subwoofer from the rear channels with authority.
At 80% Class-D efficiency, the FLX700.4 generates significantly less heat than a Class-AB amplifier at equivalent output. On a motorcycle with limited airflow and a charging system running near capacity, this matters for both thermal stability on long rides and for keeping electrical load manageable.
Crossover and Signal Control
The FLX700.4's crossover spans the full audio range — 20 Hz to 20 kHz — with four selectable slopes: 6, 12, 24, and 48 dB per octave. HPF, LPF, or Full Range mode selection. This is a significantly wider range and steeper slope capability than is common in motorcycle amplifiers, and the 48 dB/octave option is what makes the difference when running dedicated drivers.
At 48 dB/octave, you get clean separation between a midrange driver and a horn tweeter without bleed — the kind of control that keeps a front stage coherent at highway speeds. At 6 dB/octave, the gentle slope suits full-range or wideband coaxial applications.
For builds that need 254W per channel rather than 175W but do not require the steeper crossover slopes of the FLX700.4 — such as high-output coaxial builds — the FLX1000.4 offers more power with a 12 dB/octave crossover at 30 Hz – 300 Hz. The FLX700.4 is the correct choice when multi-way driver separation is part of the system design.
Input sensitivity runs 0.2V – 12V, covering both OEM Harley signal levels and standard RCA output from aftermarket head units without requiring a line driver.
System Integration
The FLX700.4 sits between the source unit and the speakers in the signal path. It 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.
Turn-on supports three modes: REM (remote trigger), DC offset detection, and VOX (audio signal sensing). VOX and DC offset are particularly useful for OEM integration on older Harley platforms where running a clean remote wire to the head unit is not straightforward.
At 50A music-level current draw, the FLX700.4 sits within the operating range of most factory Harley charging systems — no alternator upgrade required for most builds. Maximum draw is 80A; a 50A fuse is recommended on the power feed.
The FLX700.4 does not include onboard DSP. For builds requiring time alignment, multi-band EQ, or advanced signal routing — particularly on a Street Glide or Road Glide front stage running dedicated drivers — pair with a dedicated DSP processor upstream of the amp inputs.
2024+ Platform Notes
For 2023.5 CVO and 2024+ Harley-Davidson Touring models running Skyline OS, the FLX700.4 can be integrated as part of an aftermarket audio system when paired with a NAV-TV ZEN-H or ZEN-H Pro. The ZEN-H / ZEN-H Pro handles the Skyline OS signal interface — the FLX700.4 then receives the processed output and powers the speakers downstream from it. Without a NAV-TV 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: Batwing fairing — fits standard fairing amp tray.
- Harley-Davidson Road Glide: Shark nose fairing — fits standard amp tray positions.
- Harley-Davidson Ultra Limited / Ultra Classic: Fits fairing amp rack positions.
- Harley-Davidson CVO models: Fits fairing amp rack (see 2024+ note above for Skyline OS bikes).
- Harley-Davidson Trike: Compatible — fits fairing, trunk, or saddlebag amp rack positions.
- Compatible with OEM Boom! Box radios (high-level input) and all aftermarket head units (high-level or RCA inputs).
- Run 2Ω speakers for maximum rated output; 4Ω for bridged applications.
Technical Specifications
| Channels | 4-Channel |
| Amplifier Class | Class D |
| Power Output — 4Ω Stereo @ 14.4V | 120W × 4 RMS |
| Power Output — 2Ω Stereo @ 14.4V | 175W × 4 RMS |
| Power Output — 4Ω Bridged @ 14.4V | 350W × 2 RMS |
| Total RMS Power | 700W |
| Efficiency | 80% |
| Signal-to-Noise Ratio | 91 dB (A-weighted, 20 Hz – 20 kHz) |
| THD + N | 0.1% @ 2Ω per channel (10% rated power) |
| Damping Factor | 200 |
| Frequency Response | 20 Hz – 20 kHz (±3 dB) |
| Crossover Modes | LPF / Full Range / HPF (selectable) |
| Crossover Range | 20 Hz – 20 kHz |
| Crossover Slopes | 6 / 12 / 24 / 48 dB per octave |
| Input Sensitivity | 0.2V – 12V |
| Inputs | High-level or Low-level RCA |
| Turn-On Modes | REM / DC Offset / VOX |
| Operating Voltage | 9V – 16V |
| Current Draw (Music) | 50A |
| Current Draw (Maximum) | 80A |
| Recommended Fuse | 50A |
| Weather Resistance | Outdoor-rated — moisture and vibration resistant |
| Dimensions — Chassis Only | 104 × 125 × 51 mm (4.1 × 4.9 × 2.0 in) |
| Dimensions — With Mounting Brackets | 134 × 125 × 51 mm (5.3 × 4.9 × 2.0 in) |
Australia Shipping:
- Under $500 → $19.95
- $500–$2,500 → $14.95
- Over $2,500 → FREE
- Bulky items → +$24.95 surcharge (waived over $2,500)
Fast dispatch from Brisbane. Same-day shipping on in-stock orders before 1pm AEST.
Change-of-mind returns: We accept returns within 7 days of delivery on unused, unopened products in original sealed packaging. Restocking fees apply (20–30%). Return shipping is the customer's responsibility.
No returns on opened audio gear, installed items, custom orders, or special-order products. Please check fitment carefully before installing.
Faulty or incorrect items: If you experience an issue, contact us with photos/video and your order number. We'll assess the claim and arrange repair, replacement, or refund for verified faults under the Australian Consumer Law.
Fitment assistance: If you're unsure about compatibility, reach out before ordering—we're happy to help.