JL Audio C1-400x C1 Series 4" 10cm Coaxial Car Door Dash Speakers 35w RMS Pair
Couldn't Load Pickup availability
The JL Audio C1-400x is a pair of 4" (100 mm) coaxial car speakers rated at 35W RMS, part of JL Audio's entry-level C1 Series. They suit door and dashboard locations and are designed to drop in behind factory grilles.
This listing is the 4" C1-400x. The JL Audio C1 Series is also available as the 5.25" C1-525x and the 6.5" C1-650x coaxial pairs.
Key specifications
- Size: 4 inch (100 mm) coaxial
- Tweeter: 0.75 inch (19 mm) edge-driven aluminium dome, neodymium magnet
- Power handling: 35W RMS (105W peak)
- Recommended amplifier power: 10–50W RMS per channel
- Sensitivity: 84.5 dB @ 1W / 1m
- Impedance: 4 Ω
- Frequency response: 64 Hz – 24 kHz ± 3 dB
- Mounting: breakaway tabs for four-hole or two-hole locations
- Grilles: not included
- Sold as: pair
C1 Series 4-inch (100 mm) coaxial speaker system
4-inch (100 mm) woofer paired with a 0.75-inch (19 mm) aluminium dome tweeter in a coaxial configuration.
C1 speakers are built for straightforward fitment behind factory grilles. Breakaway mounting tabs on the woofer frame allow installation in four-hole or two-hole configurations.
The woofer uses a proprietary stamped steel 4-inch (100 mm) frame and a DMA-optimized motor system, developed using JL Audio's FEA modelling expertise. A mineral-filled, injection-moulded polypropylene cone is paired with a rubber surround and a carefully engineered spider to control voice coil motion and prevent back-plate contact. Tinsel leads are routed through the spider to reduce fatigue and buzzing.
The edge-driven aluminium dome tweeter delivers high-frequency clarity with strong off-axis response. It uses a silk surround suspension, Ferrofluid in the voice coil gap, and a neodymium magnet circuit. A true 2nd-order high-pass filter improves smoothness and power handling.
Sold as a pair. Grilles not included.
Explore the full range in JL Audio C1 Speakers.
Specification
| Size | 4 Inch |
|---|---|
| RMS Power | 50W |
| Shape | Round |
| Type | Coaxial |
| Series | C1 |
| Article Number | C1-400X |
| Country of Manufacture | China |
More specs
| |
What's Included
- C1-400x
JL Audio
About the JL Audio C1-400X
From our tech experts at CEN
JL Audio C1 Series 4 inch coaxial speakers, with the tweeter mounted in the centre of the woofer, rated at 50w RMS.
Who it suits
Drivers replacing tired factory speakers who want a clear improvement without relocating tweeters. C1 is the straightforward upgrade over factory speakers.
Our tech experts advise
Sizes, adapter rings and harnesses vary by vehicle, year and trim, so we confirm what your car takes before ordering. Door treatment matters as much as the speaker, and JL drivers repay an amplifier. Installation is priced per vehicle, so get in touch with your make, model and year and we will confirm what it needs. See car audio installation.
Explore the full JL Audio range at CEN, with fast UK dispatch and expert advice from our Nottingham team. Shop all JL Audio
Recommended For You
Discover more top-rated gear, handpicked to go with what you're viewing
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
More from JL Audio C1 Speakers
More options from the same range, in stock and ready to go
PopularJL Audio C1-650x C1 Series 6.5" 16.5cm Coaxial Car Door Speakers 50w RMS Pair
RRP £84.90Save 5%£79.90
JL Audio C1-690x C1 Series 6x9" Coaxial Car Parcel Shelf Speakers 60w RMS Pair
RRP £119.00Save 8%£109.00
Best SellerJL Audio C1-650 C1 Series 6.5" 16.5cm Component Car Door Speakers 50w RMS Pair
£129.00
JL Audio C1-650se C1 Series 6.5" 16.5cm Component Car Door Speakers 50w RMS Pair
£159.00
JL Audio C1-690tx C1 Series 6x9" Coaxial Car Parcel Shelf Speakers 60w RMS Pair
RRP £149.00Save 6%£139.00
Frequently Asked Questions
Q: Will these speakers fit my car?
A: Most car speakers are standard sizes, but mounting depth and fitting rings vary by vehicle. Check the size in the Specification tab against your vehicle, or contact CEN with your registration and we will confirm fitment and any adapters or fitting kits you need.
Q: Do I need an amplifier to run these speakers?
A: Not always. Most speakers will run from a standard head unit, but a dedicated amplifier lets them perform at their best, particularly for component sets and higher power handling models. The RMS figure in the Specification tab is the guide to how much clean power they can use.
Q: What is the difference between coaxial and component speakers?
A: Coaxial speakers combine the tweeter and woofer in one unit for a simple like-for-like upgrade. Component sets separate the tweeter and woofer with a crossover for better imaging and detail, and suit installs where sound quality is the priority.
Q: Do these come as a pair?
A: Unless stated otherwise, car speakers are sold in pairs. Check the product title and What's Included tab, which lists exactly what is in the box.
Q: Can CEN fit these speakers for me?
A: Yes. CEN offers professional installation from our Nottingham premises. Contact us to book an installation slot or ask for a fitting quote.
Q: Will the JL Audio C1-400x fit two-hole speaker mounts?
A: Yes. Breakaway mounting tabs on the woofer frame allow installation in four-hole or two-hole mounting configurations.
Q: Are grilles included with the C1-400x?
A: No. The C1-400x is sold as a pair without grilles and is designed to fit behind factory grilles.
Q: What amplifier power suits the C1-400x?
A: JL Audio recommends 10 - 50W RMS per channel.
Not Sure Where to Start?
Straightforward advice and the latest news from our Nottingham team.
All Guides and News →
Car Audio
Christmas Gift Guide 2026: Car Audio, Dash Cams and Outdoor Tech
Read the guide →
Car Audio
Upgrading Car Audio Without Replacing the Factory Stereo
Read the guide →
Car Audio
Amplifier Wiring Kits Explained: Gauge, Fuses and Earths
Read the guide →
Car Audio
New at CEN: Option Audio Drive-10Flat — Golf Mk8 Bass, Zero Boot Space Lost
Read more →
Car Audio
Car Speaker Sizes Explained: What Fits Your Car
Read the guide →
Car Audio
Alpine iLX-F905D Halo9 Review: The Big-Screen Upgrade for Almost Any Car
Read more →