REL Q400E Active Subwoofer

The REL Q400E is a high-performance active sub-bass system developed during the era when REL established its reputation for combining deep low-frequency extension with audiophile-grade integration. Rather than pursuing exaggerated mid-bass impact, the Q400E was engineered around REL’s long-standing philosophy of reproducing the lowest audible frequencies with speed, control, and natural system integration.

Built around a substantial long-throw 300mm driver and a powerful MOSFET amplifier, the Q400E uses REL’s distinctive Zero-Q closed-box loading system, allowing the enclosure to operate below normal system resonance for exceptionally deep and controlled bass reproduction.

A defining feature of the Q400E is its flexibility within both stereo and home theatre environments. REL’s high-level Neutrik Speakon connection allows the subwoofer to receive the same signal character as the main speakers, greatly improving tonal integration and timing consistency. Simultaneously, dedicated low-level/LFE inputs allow seamless integration into surround sound systems.

Specifications

• Type: Active closed-box sub-bass system
• Enclosure Volume: 25 litres
• Driver:
  • 1 × 300mm (12″) extra long-throw driver with cast chassis
• Amplifier Power:
  • 400W RMS MOSFET amplifier
• Amplifier Type: DC-coupled MOSFET design
• Frequency Response:
  • Down to 14Hz in-room (-6dB)
  • Variable crossover range approx. 26Hz – 106Hz
• Loading System: REL Zero-Q closed-box loading system
• Inputs:
  • High-level Neutrik Speakon
  • Low-level RCA inputs (+12dB and 0dB)
• Controls:
  • Separate high-level and low-level gain controls
  • Variable crossover control
  • Phase selection (0° / 180°)
  • LFE crossover bypass mode
• Protection System: REL Set-Safe protection circuitry
• Dimensions (W × H × D): 392 × 420 × 430 mm
• Weight: 30 kg

In performance terms, the Q400E is characterised by exceptional low-frequency depth, composure, and integration, particularly in two-channel music systems. Unlike many subwoofers designed primarily to add impact, the REL approach focuses on extending the natural bandwidth of the main loudspeakers while preserving timing and tonal coherence.

Its sealed-box architecture contributes to a presentation that feels:

• fast and controlled,
• highly articulate,
• and free from excessive bass overhang.

At the same time, the substantial amplifier and long-throw driver allow the Q400E to deliver genuine cinematic authority in home theatre applications.

The inclusion of simultaneous high-level and LFE connectivity also made the Q400E unusually versatile for its time—capable of supporting both purist stereo listening and full multi-channel cinema integration without compromise.

A classic REL sub-bass system—engineered for depth, musical integration, and true low-frequency realism rather than exaggerated bass effects.

Colour: Matte Black

Condition: Good

NOTE: Grille Included. Unit does not include original packaging, manual or additional accessories.