Infinity Primus 503F 5.25" Coaxial Speakers

Infinity Primus 503F 5.25" coaxial speakers deliver tighter bass and clearer highs in a compact 5-1/4" package. Built for car-audio enthusiasts upgrading factory or aftermarket systems, these speakers fit more vehicles than ever and pair Plus One+ bass with edge-driven tweeters for a defined soundstage.

• 5-1/4" 2-way coaxial design: compact footprint that fits common factory openings while delivering two‑way sound for improved imaging versus a single‑driver setup.
• Plus One+ polypropylene woofer cone with hi-roll rubber surround: larger effective cone area increases bass extension and control for punchier low end in tight spaces.
• 3/4" edge-driven silk dome tweeter: smooth high frequencies with reduced distortion at higher listening levels, helping cymbals and vocals stay crisp.
• 3-ohm impedance: enables stronger power delivery from most head units or amplifiers, boosting perceived output in a wide range of systems.
• True 4-ohm architecture: low-impedance voice coil designed to safely draw power from your source, delivering a stronger and clearer sound.
• Power handling: supports up to 40 W RMS (120 W peak), aligning with common head-unit and small-amp configurations for clean dynamics.
• Frequency response: 75–20,000 Hz covers essential vocal to treble content for balanced playback.
• Sensitivity: 91 dB @ 2.83V; higher sensitivity means more output from the same amplifier power in typical car audio setups.
• Cooling vented basket frame: assists heat dissipation during extended use, helping maintain performance over time.
• Grilles: grilles not included.
• Warranty: 1 year.
• What’s in the box: Infinity Primus 503F owner's manual; two 2-way speakers; two 9" lengths of speaker wire (each with female quick-slides on one end and tinned wire on the other); eight 1" screws; 8 speed clips; 2 adhesive-backed foam gaskets; template and specs on box.

The Primus 503F is designed to upgrade factory systems or compact aftermarket builds, delivering stronger output from your source thanks to its 3-ohm impedance and true 4-ohm architecture. The Plus One+ woofer cone provides more bass surface area for tighter, more controlled low end, while the edge-driven tweeter maintains clarity at higher volumes. The cooling vented basket frame supports sustained performance and longevity, making this pair a practical step up for enthusiasts seeking real, measurable improvements without oversized enclosures.