Polk Audio CS400i Center

Description

The Polk Audio CS400i Center Channel Speaker is a large, high-performance center channel speaker designed for home theater systems, particularly those built around Polk’s popular RTi-series loudspeakers. Introduced in the late 1990s and widely used throughout the early 2000s, the CS400i was engineered to deliver powerful, intelligible dialogue and a cohesive front soundstage for surround-sound systems. With its robust cabinet, dual mid-bass drivers, and advanced Polk technologies, the CS400i quickly became one of the company’s most respected center channel designs.

In a home theater system, the center speaker is responsible for reproducing most of the dialogue and a significant portion of the on-screen action. The CS400i was designed specifically to handle this critical role. Its driver configuration features two 6.5-inch Dynamic Balance mid-woofers paired with a 1-inch trilaminate dome tweeter, a combination intended to deliver strong midrange clarity while maintaining smooth high-frequency detail.

Polk’s Dynamic Balance driver technology was developed to reduce resonance and distortion in the speaker cones. By carefully analyzing materials and geometry, Polk aimed to produce drivers that operate more efficiently and with fewer unwanted vibrations. In the CS400i, this approach helps maintain clean, natural vocal reproduction—an essential quality for movie dialogue and television programming.

Another important feature of the CS400i is Polk’s Power Port bass technology, which improves low-frequency performance compared with conventional ported designs. The rear-mounted port helps the speaker produce deeper and more controlled bass, allowing the center channel to reproduce both dialogue and effects with greater impact. Additionally, Polk included ARC (Acoustic Resonance Control) to minimize cabinet vibrations and reduce coloration in the sound.

Because the CS400i was designed to match Polk’s RTi-series speakers—including the RT2000i, RT1000i, RT800i, RT600i, and RT55i—it integrates seamlessly with those models to create a cohesive front soundstage. This timbre matching ensures that sound pans smoothly across the front speakers during movie playback, maintaining consistent tonal balance across the system.

The speaker’s relatively high 91 dB sensitivity and 8-ohm impedance make it easy to drive with most home theater receivers. Despite its efficiency, the CS400i can handle substantial amplifier power—up to 250 watts—allowing it to perform well in larger listening rooms or systems with powerful amplifiers.

Physically, the CS400i is larger than many center speakers, measuring nearly 19 inches wide and over 13 inches deep. This size reflects its substantial internal volume and large drivers, which contribute to its strong output and dynamic capability. The cabinet is magnetically shielded, allowing placement near televisions without interfering with picture quality—a particularly important feature during the era of CRT displays.

Although modern center speakers often feature slimmer designs or three-way driver configurations, the CS400i remains well regarded among vintage home-theater enthusiasts for its robust construction and powerful, articulate sound.

Review Quotes

• “One of the best two-way center speakers Polk has ever made.”

• “From the softest whisper to the loudest explosion… definitely hits the mark.”

• “Produces clear dialogue and strong home-theater performance.”

Key Specifications

• Speaker Type: 2-way center channel speaker

• Drivers:

  • 2 × 6.5-inch Dynamic Balance mid/woofers

  • 1 × 1-inch trilaminate dome tweeter

• Frequency Response: 50 Hz – 25,000 Hz (-3 dB)

• Sensitivity: 91 dB

• Nominal Impedance: 8 ohms

• Recommended Amplifier Power: 20 – 250 watts

• Bass System: Rear Power Port bass-reflex design

• Cabinet Technology: ARC (Acoustic Resonance Control) to reduce cabinet resonance

• Connections: Dual 5-way binding posts for bi-wiring or bi-amping

• Magnetic Shielding: Video-shielded for placement near televisions

• Dimensions (W × H × D): 18-3/4 × 8-11/16 × 13-3/4 in

• Finish: Black vinyl cabinet

• Compatible Speaker Series: Polk RT2000i, RT1000i, RT800i, RT600i, RT55i