Polk Audio Reserve R400 Centre Speaker Black

The Polk Audio Reserve R400 is the flagship centre channel speaker in Polk’s Reserve series, sitting above the compact R300 with a larger dual-driver configuration designed for dedicated home cinema systems. Where the R300 uses a sealed enclosure, the R400 employs dual rear-firing X-Ports — Polk’s proprietary bass reflex design — delivering deeper low-frequency extension down to 48Hz and higher sensitivity (89dB) for more efficient amplifier matching.

Driver Technology

At the heart of the R400 are two 165mm (6.5″) Turbine Cone mid/bass drivers. The Turbine Cone design combines a foam core with moulded turbine geometry, increasing stiffness and damping without adding mass — the result is improved transient response and reduced colouration across the critical midrange band where dialogue sits. High frequencies are handled by a 25mm Pinnacle Ring Radiator tweeter, a concentric ring design that achieves wide, even dispersion through a precision-machined waveguide. The tweeter’s output extends to 39kHz, earning Hi-Res Audio certification from the Japan Audio Society.

Cabinet & Bass Loading

The R400’s enclosure uses Polk’s dual rear X-Port bass reflex system. Unlike a conventional rear port, the X-Port uses specially shaped internal pipes to smooth airflow exiting the cabinet, reducing turbulence noise at high output levels. Power Port 2.0 further refines low-frequency output by controlling the boundary interaction between the port exit and the surface the speaker sits on. Internal bracing is designed using Laser Doppler Vibrometry (LDV) to identify and eliminate panel resonances — point-to-point braces are placed at calculated stress points, and Cabinet Resonance Control further damps residual vibration.

Home Cinema Integration

The R400 carries both IMAX Enhanced and Dolby Atmos compatibility certifications, ensuring it meets the performance requirements for immersive audio formats. A single set of nickel-plated 5-way binding posts accepts bare wire, spade, or banana plug connections. The magnetic grille attaches without visible fixings, preserving the clean cabinet aesthetic. At 615mm wide, the R400 is sized to sit beneath displays up to 55″ without visual overhang.