JL Audio C1-400x Coaxial Speaker System: 4" (100 mm) Woofer, 0.75" (19 mm) Aluminium Dome Tweeter (Sold as pair)

SKU C1-400x

C1 speakers deliver real substance and great audio performance in a format designed for easy fit behind factory grilles.

To facilitate fit, breakaway mounting tabs on the woofer frame allow the C1-400x to be installed in four-hole or two-hole mounting configurations. C1 woofer drivers benefit from proprietary FEA modelling and JL Audio’s expertise in low-frequency driver design. This knowledge is used to create speakers that can play loudly while maintaining a smooth, dynamic, low distortion sound.

At the core of the C1-400x is a proprietary, stamped, steel 4-inch (100 mm) frame and a DMA-optimized motor system. A mineral-filled, injection-moulded polypropylene cone is suspended with a rubber surround on the front, and a carefully engineered spider at the top of the voice coil, to precisely control motion and prevent impact between the voice coil and the backplate.

Tinsel leads are carefully routed and attached to the spider to prevent fatigue and buzzing. These are the same kinds of features and materials normally found on much more expensive loudspeakers. Equipped with a true, edge-driven, aluminium dome tweeter, C1 speakers stand further apart from others in its category with superior high-frequency clarity and definition.

The tweeter’s design has an inherently excellent off-axis response and high-frequency extension. It also benefits from the damping of a silk surround suspension and Ferrofluid in the voice coil gap, along with the superior strength of a neodymium magnet circuit. A true, 2nd order high-pass filter is employed to further enhance smoothness and improve power handling.


  • Continuous Power Handling (RMS): 35 W
  • Peak Music Power: 105 W
  • Recommended Amplifier Power (RMS): 10 – 50 W / Ch.
  • System Efficiency: 84.5 dB @ 1 W / 1 m
  • System Nominal Impedance: 4 Ω
  • System Frequency Response: 64 Hz – 24 kHz ± 3 dB
  • Frame Outer Diameter* (A): 4.03 in / 102 mm
  • Grille Tray Outer Diameter (B): N/A
  • Motor Outer Diameter (C): 2.33 in / 59 mm
  • Frontal Coaxial Tweeter Protrusion** (D): 0.61 in / 16 mm
  • Frontal Grille Protrusion (E): N/A
  • Mounting Hole Diameter (F): 3.70 in / 94 mm
  • Mounting Depth (G): 1.81 in / 46 mm
  • *Does not take into account mounting tabs **Frontal coaxial tweeter protrusion measured from mounting surface