Cicada FLX vs Hertz SP: Which Motorcycle Amplifier Is Right for Your Harley?

Product Comparison · Amplifiers

Cicada Audio's FLX range and Hertz's SP range are the two four-channel motorcycle amplifier lines we get asked to compare most at MAA. Both are compact, weather-conscious Class-D designs built for Harley fairings, and both can anchor anything from a tidy factory-radio upgrade to a full high-output build. They pull in slightly different directions: Hertz leans on a sealed IP55 chassis, high efficiency and strong factory-radio integration, while Cicada spans a much wider output range, from the 125W × 4 FLX500.4 to the 542W × 4 FLX2000.4, with two models carrying onboard DSP. Neither is objectively better. They are built around different priorities, and the right choice depends on your speakers, your electrical system and how loud you actually ride.

How do the Cicada FLX and Hertz SP four-channel amplifiers compare on paper?

All power figures below are RMS at the rated 14.4V. Both 2Ω and 4Ω speakers are common in Harley audio builds, so the relevant column is the one matching the actual load presented to each amplifier channel; the 4Ω and bridged figures are included alongside 2Ω so you can match the amp to your speakers. AUD pricing checked July 2026.

On the two PRO models, “6 processed channels” means four amplified outputs plus two line-level pass-through outputs. The pass-throughs carry a tuned signal to a second amplifier; they do not power speakers on their own. Current tuning of the FLX700.4PRO and FLX1400.4PRO is done over USB-C using Cicada's Windows PC software; Cicada's smartphone DSP apps are no longer supported, and Bluetooth on these models is for audio streaming. Neither Hertz SP model has onboard DSP: their built-in analogue crossover and bass-boost controls cover basic setup, but per-channel EQ, time alignment, advanced routing and independent output processing require a standalone DSP.

Weather sealing, efficiency and factory-radio integration

Raw wattage is only part of the picture, and on a factory-radio daily rider it may not be the deciding factor. This is where the two ranges differ most.

Hertz SP amplifiers accept analogue speaker-level signals up to 22V and include ART automatic turn-on/off plus USS load simulation for compatible factory radios that monitor speaker impedance. Their IP55 aluminium chassis, conformal-coated PCB, protected controls and sealed power, signal and speaker connections give them the most clearly documented environmental protection in this comparison, and the ADC (Advanced D-Class) output stage is rated up to 87% efficient. Of the amplifiers here, the SP4.500 also has the lowest manufacturer-published musical-consumption figure (27A), which makes it likely the easiest of these amplifiers to support electrically.

Cicada FLX accepts compatible low-level or speaker-level analogue signals through a 0.2V to 12V input range. Turn-on options vary by model: the FLX500.4, FLX700.4 and both PRO models add VOX to REM and DC-offset turn-on, while the FLX1000.4, FLX1400.4 and FLX2000.4 currently list REM and DC-offset only. Cicada does not publish an IP number for these amplifiers: the standard models are built for motorcycle and powersports use, and the two PRO models add a conformal-coated board. Efficiency sits around 79 to 80%, and the PRO models add Bluetooth audio streaming, with DSP tuning done over USB-C using Cicada's Windows PC software. Where Cicada pulls ahead is range: a lower entry price, more output tiers, and onboard DSP options that Hertz's SP line does not have.

These high-level-input specifications apply to compatible analogue radio outputs. On 2023.5 CVO and 2024-later Skyline OS / A2B systems, an appropriate digital audio interface is required before either range can be integrated, and high-level capability does not by itself correct factory EQ or remove any required radio configuration.

An IP or conformal-coating claim does not replace protected mounting: keep the amplifier and its wiring away from direct pressure washing, standing water and unsupported cable strain.

Published musical-current figures are useful manufacturer guidance but are not necessarily measured to the same test method across brands, and they are not continuous full-power figures. Do not use them alone to size wiring, fusing or charging-system upgrades.

Dimensions are the overall figure including mounting brackets or terminals. There is no simple “one brand is smaller” rule. The FLX500.4, FLX700.4 and FLX700.4PRO have the smallest mounting footprint here, roughly 59 to 62 mm shorter and 5 mm narrower than the SP4.500, while the SP4.500 has the lowest chassis height by about 2 mm. The FLX1000.4 is also shorter than the SP4.500, and the FLX1400.4 is shorter and narrower than the SP4.900. Actual fairing fitment still depends on the amp rack, connector direction, cable exits and available clearance.

Which amplifier should I choose for a daily-rider Harley?

For a clean upgrade over a stock or factory-amplified system, the two natural starting points are the Cicada FLX500.4 ($680) and the Hertz SP4.500 ($800). The FLX500.4 is the cheapest amp here and carries Cicada's flexible analogue crossover (up to 48 dB per octave), which suits multi-way front stages. The SP4.500 has the lowest manufacturer-published musical-consumption figure here (27A) and the IP55 sealed chassis, which makes it likely the easiest to support electrically and gives it the most clearly documented environmental protection in this comparison. The SP4.500 delivers 150W × 4 at 2Ω, which suits compatible speakers in that power range when gains and crossovers are set correctly. Both are the lower-output entry options here, and both still need correctly sized fused power and ground wiring; the bike's charging capacity should be assessed against the complete system rather than assumed.

Hertz

SP4.500

600W RMS, four-channel, IP55 Class-D amplifier with the lowest published musical-consumption figure in this comparison at 27A, built for clean factory-radio integration in tight Harley fairing space.

$800 View Product →

Which amplifier should I choose for a mid-tier or high-output build?

In the middle of the range the two brands sit close together. The Cicada FLX700.4 ($855, 175W × 4 at 2Ω) is a small step in price and output above the SP4.500, and the Cicada FLX1000.4 ($1,195, 254W × 4) lands just under the Hertz SP4.900 ($1,310, 250W × 4) at similar output for less money. Choose on the things that separate them: the SP4.900 brings the IP55 seal, USS and ART integration and speaker-level inputs, while the FLX1000.4 brings a slightly lower price. Crossover capability also varies: the FLX500.4 and FLX700.4 offer unusually wide analogue adjustment (20 Hz to 20 kHz with selectable slopes), whereas the FLX1000.4, FLX1400.4 and FLX2000.4 use conventional 30 to 300 Hz filters at 12 dB per octave, and the Hertz SP amplifiers provide adjustable 50 Hz to 5 kHz high- and low-pass filters. The FLX PRO models go further with full DSP control.

At the top, the Cicada line keeps going where the SP line stops. The FLX1400.4 (350W × 4 at 2Ω, $1,535) and the FLX2000.4 (542W × 4, $1,875) have the highest rated four-channel output in this comparison. That extra ceiling matters most once you are running higher-power speakers or dedicated mid-bass drivers, but it comes with real electrical requirements: the FLX700.4PRO, FLX1400.4, FLX1400.4PRO and FLX2000.4 all use 4 AWG power inputs, and the FLX2000.4 additionally needs a lithium battery to hold voltage at rated output.

If you want the amp to handle its own tuning rather than running a separate DSP, Cicada offers two integrated options: the FLX700.4PRO ($1,195) and the FLX1400.4PRO ($1,875), each with a six-channel processor (four amplified, two pass-through) and Bluetooth streaming, tuned over USB-C with Cicada's Windows PC software. Hertz does not currently offer an SP four-channel amplifier with integrated DSP.

Cicada Audio

FLX1400.4

1,400W RMS, 4-channel Class-D amplifier for maximum Harley front-stage output. Requires 4 AWG power and ground wiring.

$1,535 View Product →

Quick picks

What are the real-world pros and cons of each brand?

Hertz SP, pros: IP55 sealed alloy chassis with conformal-coated PCB and sealed connections, high efficiency (up to 87%), the lowest manufacturer-published musical-consumption figure here on the SP4.500 (27A), and speaker-level inputs up to 22V with USS load simulation and ART automatic turn-on for clean factory-radio integration.
Hertz SP, cons: no onboard DSP on either model: the built-in analogue crossover and bass boost cover basic setup, but per-channel EQ, time alignment and advanced routing require a separate processor. The SP line also has only two output tiers, so there is no sub-$800 entry option and no ultra-high-output option.

Cicada FLX, pros: the widest output and price range (from the FLX500.4 to the FLX2000.4, starting at $680), two models with onboard DSP and Bluetooth, wide analogue crossovers up to 48 dB per octave on the FLX500.4 and FLX700.4 (and full DSP crossover on the PRO models), and the highest rated four-channel output here (FLX2000.4).
Cicada FLX, cons: no published IP rating (standard models are built for powersports use but not IP-numbered), the FLX700.4PRO, FLX1400.4, FLX1400.4PRO and FLX2000.4 use 4 AWG power inputs (and the FLX2000.4 also needs a lithium battery), and current draw rises at the top of the range.

Do I need to match my amplifier brand to my speaker brand?

No. Amplifiers and speakers do not need to share a badge to work well together. What matters is matching impedance, RMS capability, sensitivity, channel configuration, crossover requirements, gain structure and physical fit. We regularly wire Hertz amplifiers to Precision Power speakers and Cicada amplifiers to Hertz speakers, depending on what suits the build and the budget.

Frequently asked questions

Browse the full Cicada Audio range or the Hertz range to compare more options.