KEF Kube 12 MIE 12" 300W RMS Powered Subwoofer

Deep, High-Output Bass for Larger Rooms and Home Theater

The KEF Kube 12 MIE is a powered sealed 12" subwoofer designed for music, movies, gaming, larger living rooms, and dedicated home theaters where deeper extension and stronger output are priorities.

It combines a front-firing 12" long-throw driver, 300W RMS Class D amplification, and KEF's Music Integrity Engine DSP to help deliver controlled low-frequency performance across different listening levels and room positions.

Key Specifications

• Sold as: One powered subwoofer
• Design: Sealed, front-firing
• Driver: 300 mm (12")
• Amplifier: Built-in Class D
• Amplifier power: 300W RMS
• Frequency response: 22 Hz–140 Hz (±3 dB)
• Maximum output: 114 dB measured at 1 meter
• Variable low-pass filter: 40–140 Hz, plus LFE mode
• Inputs: RCA phono, speaker-level input, KW1 expansion port
• Power requirements: 100–240V AC, 50/60 Hz

Who Should Choose the Kube 12 MIE?

Choose the Kube 12 MIE when you want more low-frequency extension and output than the smaller Kube models while keeping a sealed enclosure and straightforward system integration.

It is especially well suited to larger living rooms, media rooms, dedicated home theaters, music systems, and gaming setups where stronger bass impact is important.

If you need maximum output from the Kube range, the larger Kube 15 MIE provides even deeper extension and higher published output.

300W RMS Built-In Amplification

The Kube 12 MIE includes a 300W RMS Class D amplifier, so no external power amplifier is required. Connect the subwoofer to your audio system and AC power, then configure its level, crossover, phase, and placement settings.

The 300W figure is KEF's published RMS amplifier-output specification.

22 Hz Extension and 114 dB Output

KEF specifies a frequency response of 22 Hz–140 Hz at ±3 dB and a maximum output of 114 dB measured at 1 meter.

Actual in-room bass will still depend on placement, room dimensions, construction, listening position, crossover settings, and calibration.

Music Integrity Engine and iBX

KEF's Music Integrity Engine uses proprietary DSP algorithms to coordinate the driver, amplifier, and sealed enclosure.

iBX Intelligent Bass Extension dynamically adjusts low-frequency operation to help maintain bass extension and control across different listening levels.

Flexible RCA and Speaker-Level Connections

The Kube 12 MIE includes RCA line-level inputs for AV receivers, processors, preamps, and integrated amplifiers with compatible outputs.

It also provides speaker-level inputs, allowing integration with compatible stereo amplifiers and receivers that do not have a dedicated subwoofer output.

KEF SmartConnect

KEF SmartConnect automatically detects whether one or two RCA cables are connected and adjusts input gain accordingly. This simplifies mono or stereo RCA integration without requiring a Y-adapter for a single-cable connection.

Optional KW1 Wireless Connection

The Kube 12 MIE does not have built-in wireless audio. Wireless subwoofer operation requires the optional KEF KW1 Wireless Subwoofer Adapter Kit, connected through the dedicated expansion port.

The Kube 12 MIE still requires AC power when the KW1 is used.

Three Placement EQ Presets

The Kube 12 MIE provides three placement-dependent EQ settings to help compensate for room boundaries:

• Room: For more open placement
• Wall/Cabinet: For placement close to a wall or in suitable cabinetry
• Corner: For corner placement where boundary reinforcement is strongest

Multiple Power Modes

The Kube 12 MIE supports signal-sensing Auto Wake, Always On operation, and 12V trigger control for compatible systems.

Dimensions and Weight

• Height: 410 mm (16.1")
• Width: 393 mm (15.5")
• Depth: 410 mm (16.1") including rear panel and feet
• Weight: 18.6 kg (41.0 lb)

What's Included?

• 1 KEF Kube 12 MIE powered subwoofer
• Power cord
• Euroblock speaker-level connector
• User manual and warranty information

The optional KEF KW1 wireless adapter, RCA/LFE cable, and other system cables are sold separately.

Complete Your Audio System

• Subwoofers
• AV Receivers & Surround Sound
• KEF Speakers & Audio

Need Help Choosing the Right Kube?

Send Bear Security Shop your room dimensions, speakers, amplifier or AV receiver model, and listening goals. We can help compare the Kube 10, Kube 12, and Kube 15 MIE and recommend the best connection and placement approach.

Is the KEF Kube 12 MIE powered?

Yes. It includes a built-in 300W RMS Class D amplifier.

What size driver does it use?

The Kube 12 MIE uses one front-firing 12" driver.

What is the frequency response?

KEF specifies 22 Hz–140 Hz at ±3 dB.

What is the maximum output?

KEF specifies 114 dB maximum SPL measured at 1 meter.

What crossover range does it support?

The variable low-pass filter operates from 40 Hz to 140 Hz, plus an LFE mode for AV receiver or processor integration.

Can I connect it to an AV receiver?

Yes. The Kube 12 MIE includes RCA inputs for connection to compatible subwoofer or LFE outputs.

Can I use it with an amplifier that has no subwoofer output?

Yes. It includes speaker-level inputs for integration with compatible amplifiers and receivers.

Does the Kube 12 MIE have built-in wireless audio?

No. Wireless operation requires the optional KEF KW1 Wireless Subwoofer Adapter Kit. The subwoofer still requires AC power.

What does KEF SmartConnect do?

SmartConnect detects whether one or two RCA cables are connected and automatically adjusts input gain. A Y-adapter is not required for a single RCA connection.

What placement EQ settings are available?

The Kube 12 MIE provides three placement EQ presets for room, wall/cabinet, and corner positioning.

Does it support automatic power-on?

Yes. It supports signal-sensing Auto Wake, Always On mode, and 12V trigger control.

What are the dimensions?

The Kube 12 MIE measures approximately 16.1" H × 15.5" W × 16.1" D including the rear panel and feet.

How much does it weigh?

KEF specifies a weight of 18.6 kg, approximately 41 lb.

What comes in the box?

KEF includes the Kube 12 MIE subwoofer, power cord, Euroblock speaker-level connector, and user manual/warranty information.