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The Kicker 51KPX3004 is a 4-channel Class D amplifier rated at 300W RMS, part of Kicker's KPX series. It delivers 75W x 4 at 2 ohms or 45W x 4 at 4 ohms in a compact, weather-resistant enclosure suited to motorcycles, boats and vehicles with limited space.
Key specifications
- Channels: 4, Class D
- RMS power: 75W x 4 at 2 ohms, 45W x 4 at 4 ohms
- Bridged: 150W x 2 at 4 ohms
- Crossover: 60/80/100/120 Hz high-pass, 12 dB/octave
- Frequency response: 20 Hz–20 kHz
- Fuse: 40A
- Dimensions: 4.3 cm H x 8.4 cm W x 21.7 cm L
KPX 300W Weather-Resistant 4-Channel Amp (51KPX3004)
The KPX300.4 delivers strong power in a compact, weather-resistant build suited to motorcycles, boats or any vehicle with limited space. It drives up to four speakers with clarity and precision while placing minimal strain on your charging system.
Independent gains and a variable 12 dB/octave crossover ensure optimal speaker performance and sonic clarity. A wide input range makes it straightforward to integrate with factory or aftermarket head units. If you need a dedicated subwoofer channel alongside this amp, Kicker also offer the Kicker 46CXA400.1 mono subwoofer amplifier.
Features
- Compact design fits under fairings and in tight spaces
- Powers 2- or 4-speaker systems
- Up to 300+ watts of clean power
- Weather-resistant construction for outdoor and marine use
- Variable 12 dB/octave hi-pass crossovers: 60/80/100/120 Hz
- Minimal strain on the charging system
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Specification
| Power (watts/ch), 2 Ohm Stereo | 75x4 |
|---|---|
| Power (watts/ch), 4 Ohm Stereo | 45x4 |
| Power (watts/ch), 4 Ohm Bridged Mono | 150x2 |
| Dynamic Power (watts) | 350 |
| Output Channels | 4 |
| Voltage (V) | 12 |
| Class | D |
| Fuse Rating (A) | 40A |
| Cable Gauge (AWG) | 8 |
| Amp Turn-On | DC Offset / 12V |
| Frequency Response | (Hz) 20-20k |
| Filter | High-Pass |
| Controller | N/A |
| Crossovers | 60/80/100/120Hz hi-pass, 12dB/octave |
| Input Channels | 2 / 4 |
| Input Type | High Level / Low Level |
| Input Sensitivity Low Level | N/A |
| Input Sensitivity High Level | 250mV-10V |
| Height (cm) | 4.3 |
| Width (cm) | 8.4 |
| Length (cm) | 21.7 |
What's Included
- Kicker 51KPX3004
Kicker
About the Kicker 51KPX3004
From our tech experts at CEN
The Kicker 51KPX3004 is a 4-channel Class D amplifier rated at 300W RMS, delivering 75W x 4 at 2 ohms or 45W x 4 at 4 ohms. It can also run bridged at 150W x 2 at 4 ohms. Its weather-resistant build and compact dimensions — 21.7cm long, 8.4cm wide and 4.3cm tall — make it a practical choice for motorcycles, boats and cars with limited space.
Who it suits
Riders and boaters wanting clean amplification will appreciate the weather-resistant, compact casing. It also suits car builds where boot or under-seat space is limited. Those wanting a dedicated subwoofer channel alongside can pair it with the Kicker 46CXA400.1.
Our tech experts advise
Use 8 AWG power cable for this amp. It accepts both high-level and low-level inputs, so it works with factory or aftermarket head units without modification. The variable high-pass crossover — 60, 80, 100 or 120 Hz at 12 dB/octave — lets you tune the output to your speakers. Car audio installation is priced per vehicle; see our Nottingham fitting page for details.
Explore the full Kicker range at CEN, with fast UK dispatch and expert advice from our Nottingham team. Shop all Kicker
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Have it Fitted By Our Team
Our team fits car audio, stereos, dash cams and vehicle security at our workshop in Beeston, Nottingham. Tell us your vehicle and we'll confirm the parts and a fitted price.
- 1
Tell us your vehicle
Make, model and year, and what you'd like fitted.
- 2
We confirm the parts
Fascia, wiring and interfaces checked for your car, with a fitted price.
- 3
Fitted at our workshop
Bring it to our Beeston workshop and we do the rest.
Unit 25 Technology Drive, Beeston, Nottingham NG9 1LA
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Kicker LX850.1 Amp 1 Channel Mono Subwoofer Car Amplifier up to 850w RMS
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Kicker KEY200.4ISO Amp 4 Channel Full Range Car Smart Amplifier & DSP 4x50w
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Frequently Asked Questions
Q: How do I choose the right amplifier for my speakers or subwoofer?
A: Match the amplifier's RMS output per channel to the RMS handling of your speakers or subwoofer at the same impedance. The Specification tab lists the power figures. If in doubt, contact CEN with your setup and we will recommend a match.
Q: What wiring do I need to install this amplifier?
A: You will need an amplifier wiring kit sized to the amplifier's power draw, typically including power and earth cable, a fuse, RCA leads and a remote wire. CEN stocks complete wiring kits, and the amplifier's fuse rating is the guide to the cable gauge required.
Q: What class of amplifier is this and does it matter?
A: Class D amplifiers are compact and efficient, ideal for subwoofers and modern installs. Class AB designs are traditionally favoured for outright sound quality on mid and high frequencies. The class is listed in the Specification tab where provided.
Q: Will an amplifier work with my factory head unit?
A: Yes, in most cases. If your head unit has no RCA outputs you will need a line output converter to feed the amplifier a clean signal. CEN stocks line output converters and can advise the right one for your vehicle.
Q: Can CEN install this amplifier?
A: Yes. CEN offers professional amplifier installation from our Nottingham premises, including secure mounting, wiring and setup. Contact us to book.
Q: Can the Kicker 51KPX3004 be used on a motorcycle or boat?
A: Yes. It has a compact, weather-resistant design that fits under motorcycle fairings and suits boats and other vehicles with limited space.
Q: How much power does the 51KPX3004 produce?
A: It delivers 45W RMS x 4 at 4 ohms, 75W RMS x 4 at 2 ohms, or 150W x 2 bridged at 4 ohms. Dynamic power is 350W.
Q: Can the 51KPX3004 run two speakers instead of four?
A: Yes. It powers two- or four-speaker systems and can be bridged to 150W x 2 at 4 ohms.
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