Product Overview
The REL HT/1205 MKII is a high-performance 12-inch powered subwoofer designed to deliver powerful and precise bass for home theater, audiophile stereo systems, and surround sound setups. It features a front-firing 12-inch driver powered by a 500-watt Class D amplifier, ensuring deep, accurate low-frequency reproduction. This subwoofer is engineered for seamless integration into various audio environments, enhancing both movie and music experiences.

Image: Angled view of the REL HT/1205 MKII 12-Inch Powered Subwoofer, showcasing its sleek black finish and front-firing driver.
Setup and Installation
Unpacking
Carefully remove the subwoofer from its packaging. Inspect the unit for any signs of damage during transit. Retain all packaging materials for future transport or servicing.
Placement
Optimal placement of the HT/1205 MKII is crucial for achieving the best bass performance. For most home theater applications, placing the subwoofer in a corner or along a wall can enhance bass output. This unit is suitable for spaces up to 400 sq ft. For larger spaces or a more elevated experience, consider using a stereo pair of subwoofers.
- Corner Placement: Often provides the most output and deepest extension.
- Wall Placement: Can offer a good balance of output and accuracy.
- Near Main Speakers: For music-focused systems, placing the subwoofer near the main stereo speakers can improve integration.
Connections
The HT/1205 MKII offers flexible connection options to integrate with your audio system.

Image: Rear panel of the REL HT/1205 MKII subwoofer, illustrating the various input connections including RCA LFE and stereo RCA inputs.
- For Home Theater (LFE): Connect an RCA cable from your AV receiver's dedicated subwoofer output (LFE or Sub Out) to the LFE input on the HT/1205 MKII. This is the primary connection method for movie playback.
- For Stereo Systems (Low Level): For music applications or stereo systems without a dedicated LFE output, connect RCA cables from your pre-amplifier's Left and Right RCA outputs to the Low Level inputs (Left/Right) on the subwoofer.
- Power Connection: Once audio connections are made, connect the supplied AC power cord to the subwoofer's power inlet and then to a suitable wall outlet.
Ensure all connections are secure before powering on the unit.
Operating Instructions
Power On/Off
The HT/1205 MKII features a power switch on the rear panel. Set it to the 'ON' position for operation. The unit also has a standby mode, indicated by a light on the rear panel, which conserves power when no audio signal is detected.
Initial Adjustments
After connecting, perform initial adjustments to integrate the subwoofer with your main speakers and room acoustics.
- Level Control: Adjust the 'LEVEL' knob on the rear panel to match the output volume of the subwoofer with your main speakers. Start with a low setting and gradually increase.
- Crossover Frequency: The 'CROSSOVER' knob determines the highest frequency the subwoofer will reproduce. Adjust this to blend seamlessly with your main speakers. A common starting point is 80Hz, but it may vary depending on your main speakers' low-frequency capabilities.
- Phase Control: The 'PHASE' switch (0° or 180°) helps ensure the subwoofer's output is in phase with your main speakers, preventing cancellation or reinforcement of bass frequencies. Experiment with both settings to find the one that produces the most impactful and coherent bass.
- Wireless Communication: The HT/1205 MKII supports HT Air Wireless technology for wireless connectivity. Refer to the separate HT Air Wireless module instructions for setup and pairing.

Image: Front view of the REL HT/1205 MKII subwoofer, highlighting its 12-inch driver.
Maintenance
Cleaning
To maintain the appearance of your HT/1205 MKII, wipe the cabinet with a soft, dry, lint-free cloth. Avoid using abrasive cleaners, solvents, or chemical sprays, as these can damage the finish. Do not apply cleaning solutions directly to the subwoofer.
General Care
- Keep the subwoofer away from direct sunlight, heat sources, and excessive moisture.
- Ensure adequate ventilation around the unit to prevent overheating.
- Do not place objects on top of the subwoofer that could block ventilation or scratch the finish.
- If moving the subwoofer, lift it carefully from the base to avoid damage to the feet or cabinet.
Troubleshooting
This section addresses common issues you might encounter with your REL HT/1205 MKII subwoofer.
| Problem | Possible Cause | Solution |
|---|---|---|
| No Sound from Subwoofer |
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| Distorted or Boomy Bass |
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| Unreliable Auto On/Off Function |
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If the problem persists after attempting these solutions, please refer to the Support section for further assistance.
Specifications
| Feature | Detail |
|---|---|
| Model Name | HT/1205 MKII |
| Speaker Type | Subwoofer |
| Mounting Type | Floor Standing |
| Material | Wood |
| Subwoofer Diameter | 12 Inches |
| Woofer Diameter | 12 Inches |
| Speaker Maximum Output Power | 500 Watts (Class D Amplifier) |
| Frequency Response | 22 Hz (-6dB) |
| Connectivity Technology | RCA, HT Air Wireless |
| Control Method | App (via HT Air Wireless) |
| Product Dimensions (D x W x H) | 17.25"D x 16.25"W x 15.25"H |
| Item Weight | 38 Pounds |
| Color | Black |
| Included Components | Subwoofer |
| Power Source | AC |
| Surround Sound Channel Configuration | 5.1, 7.1 (Compatible) |
| UPC | 857316005638 |
| Manufacturer | REL Acoustics |

Image: Diagram showing the dimensions of the REL HT/1205 MKII subwoofer: 17.25 inches deep, 16.25 inches wide, and 15.25 inches high.
Warranty Information
The REL HT/1205 MKII Powered Subwoofer comes with a Three-year warranty from the date of original purchase. This warranty covers defects in materials and workmanship under normal use. Please retain your proof of purchase for warranty claims. For detailed terms and conditions, refer to the warranty card included with your product or visit the official REL Acoustics website.
Support
For technical assistance, troubleshooting beyond this manual, or service inquiries, please contact REL Acoustics customer support. You can typically find contact information on the official REL Acoustics website or through your authorized dealer. When contacting support, please have your product model number (HT/1205 MKII) and serial number ready.
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