In Phase XTB-828R Underseat Subwoofer | 8" Passive Radiator | 400W Class D Amp | Sealed | Active Bass

Experience bass accuracy that standard active subwoofers simply can't match — the In Phase Car Audio XTB-828R Underseat Subwoofer combines an 8-inch glass fibre woven cone driver, passive radiator sealed enclosure technology, and a built-in 400W Class D amplifier in a compact four-in-one underseat design that delivers deep, controlled, audiophile-grade bass without sacrificing boot space.

Passive Radiator Sealed Enclosure — True Bass Accuracy. Unlike conventional active subwoofers, the XTB-828R uses passive radiator technology in a sealed enclosure — a combination that produces exceptionally deep, accurate, and controlled low frequencies with minimal distortion. The result is bass that you feel as much as hear, with the precision and definition that serious car audio enthusiasts demand.

8-Inch All-Weather Glass Fibre Woven Cone: The 20cm (8") glass fibre woven cone drive unit is built for durability and performance — the all-weather construction handles temperature variations and humidity without degradation, while the woven cone material delivers the stiffness and lightness needed for accurate, responsive bass reproduction.

Built-In 400W Class D Amplifier: The integrated 400W Class D amplifier provides high power handling with exceptional efficiency — delivering serious output while generating minimal heat, making it ideal for the confined space of an underseat installation. Multiple onboard controls allow precise tuning to your vehicle and audio preferences.

High & Low Level Inputs — OEM & Aftermarket Compatible High and low level inputs ensure compatibility with both aftermarket head units and OEM factory head units — no need to replace your existing stereo to enjoy upgraded bass performance. Simply connect and tune.

Four-in-One Compact Design — Underseat Fitment. The clever four-in-one enclosure design integrates the driver, passive radiator, sealed enclosure, and amplifier into a single compact unit sized specifically for underseat installation — maximising bass output while minimising the footprint in your vehicle.

Complete Wiring Kit Included: Comes complete with a wiring kit for straightforward installation.

Please note: RCA cables are not included. If connecting to an aftermarket head unit, RCA cables will be required (sold separately).

Key Specifications:

• Driver: 8" (20cm) all-weather glass fibre woven cone
• Enclosure: Passive radiator sealed active enclosure
• Amplifier: Built-in 400W Class D
• Inputs: High level & low level (OEM & aftermarket compatible)
• Design: Four-in-one underseat enclosure
• Includes: Wiring kit (RCA cables not included)