REL HT/1003 MKII Home Cinema Subwoofer

The REL HT/1003 MKII is a compact active subwoofer developed primarily for home cinema, gaming and systems requiring powerful low-frequency effects from a manageable cabinet.

A front-firing 250mm CarbonGlas driver is powered by a 300W RMS Class D amplifier, with low-frequency extension reaching 24Hz at the stated minus 6dB point.

It can operate as the main subwoofer in a smaller room, form part of a multiple-subwoofer installation or provide dedicated LFE support alongside REL models used with the main loudspeaker channels.

Compact Cabinet, Substantial Output

The HT/1003 MKII is the most compact model in REL’s Serie HT MKII range.

Its comparatively modest footprint makes it easier to position beside furniture, behind seating or along the same wall as the screen, while its amplifier and long-throw driver provide considerably greater output than the original HT/1003.

The sealed cabinet helps the driver remain controlled and avoids the airflow noise associated with an open reflex port.

250mm CarbonGlas Driver

The front-firing active driver uses REL’s CarbonGlas cone construction.

A glass-fibre primary cone is reinforced by an inverted carbon-fibre centre cap, combining low moving mass with the rigidity needed for powerful low-frequency effects.

A larger motor system, revised suspension and enlarged surround allow greater controlled movement, helping the driver reproduce sudden explosions, impacts and soundtrack peaks without becoming loose or indistinct.

The steel chassis provides a rigid mechanical foundation for the long-throw driver assembly.

Closed-Box, Front-Firing Design

The HT/1003 MKII uses a sealed cabinet with no reflex port or passive radiator.

Air trapped within the enclosure helps control the driver’s movement, supporting a fast response and gradual low-frequency roll-off.

The front-firing arrangement directs its output into the room and allows the cabinet to sit on a wide variety of firm floor surfaces without requiring operating clearance beneath a down-firing driver.

24Hz Low-Frequency Extension

REL specifies low-frequency extension to 24Hz at minus 6dB.

This allows the HT/1003 MKII to reproduce the deep effects contained within film soundtracks, television, concerts and games while adding greater weight and scale to music.

Room size, placement and bass-management settings will all influence the extension and output achieved at the listening position.

300W Class D Amplifier

A 300W RMS Class D amplifier powers the CarbonGlas driver.

The amplifier is designed to provide the current delivery and headroom required for sudden cinematic effects while operating efficiently within the compact enclosure.

REL rates its amplifier output as continuous RMS power rather than a short-duration peak figure.

Electronic Set-Safe, DC fault and output-short protection help protect the amplifier and driver under abnormal operating conditions.

Analogue PerfectFilter Technology

The HT/1003 MKII uses REL’s analogue PerfectFilter circuitry to shape and extend its useful low-frequency response.

Fast analogue crossover filters help preserve the speed and impact required for cinema while allowing the subwoofer to integrate with compact speakers, floorstanding loudspeakers and active systems.

Revised secondary filtering also allows useful output to extend further into the upper bass, helping explosions and large effects retain their full sense of pressure and scale.

Protective Subsonic Filtering

An analogue subsonic filter begins at frequencies below the subwoofer’s normal operating range.

This reduces the effect of extreme infrasonic information that may be present within some soundtracks but cannot be reproduced usefully by the driver.

Removing this unnecessary movement helps preserve amplifier headroom and keeps the driver controlled during demanding scenes.

Dedicated RCA LFE Connection

For home cinema use, the designated RCA LFE input connects to the subwoofer output of a compatible AV receiver or surround processor.

This carries the dedicated low-frequency effects channel contained within film, television and multichannel game soundtracks.

Bass management, crossover frequency, level and delay can be controlled from the connected processor, with the REL’s rear controls used to complete the installation.

Stereo Low-Level RCA Inputs

The two RCA sockets can also accept left and right low-level signals from a suitable stereo pre-amplifier, integrated amplifier, processor or active loudspeaker system.

In this arrangement, the HT/1003 MKII’s variable crossover control limits the upper frequencies reproduced by the subwoofer.

This allows the Serie HT model to support music systems where a suitable variable line-level output is provided.

Daisy-Chain RCA Outputs

Corresponding RCA outputs allow the low-level or LFE signal to be passed to another compatible subwoofer.

This can simplify multiple-subwoofer installations by avoiding the need to run an individual signal cable from the processor to every cabinet.

Each connected subwoofer retains its own amplifier, level, crossover and phase controls and should be adjusted for its individual position.

Variable 30Hz to 200Hz Crossover

The rear crossover control is continuously adjustable between approximately 30Hz and 200Hz.

When the HT/1003 MKII is connected through the dedicated subwoofer output of an AV processor, the principal crossover is normally set within the processor.

For stereo low-level use, the REL crossover should be adjusted to blend with the natural low-frequency roll-off of the main loudspeakers.

Excessive crossover settings can make upper bass sound thick or allow the location of the subwoofer to become obvious.

0 or 180-Degree Phase Adjustment

A two-position phase switch helps align the movement of the REL driver with the main loudspeakers.

The correct setting is normally the one that produces the strongest and most coherent bass at the main listening position.

AV receivers with automated room correction may also provide distance, delay and phase-related adjustment within their setup menus.

HT-Air MKII Wireless Compatibility

The HT/1003 MKII is compatible with the optional REL HT-Air MKII wireless system .

HT-Air MKII carries a low-level or LFE signal using an uncompressed 5.8GHz wireless connection, avoiding the need for a long RCA cable across the room.

The transmitter connects to the AV receiver, processor or suitable line-level output, while the receiver connects to the REL.

Wireless transmission carries the audio signal only. The subwoofer and wireless units continue to require their appropriate power connections.

Positioning the HT/1003 MKII

Begin with the subwoofer along the same wall as the screen and front loudspeakers.

A corner position can increase output and low-frequency extension, while moving the cabinet away from the corner may provide smoother and more controlled bass.

Avoid enclosing the subwoofer tightly within furniture, blocking the front driver or preventing ventilation around the amplifier panel.

Final placement should be determined by listening or room measurement rather than appearance alone.

AV Receiver Setup

1. Connect the receiver or processor’s subwoofer output to the REL’s LFE input.
2. Place the HT/1003 MKII along the front wall in the intended starting position.
3. Set the REL level conservatively before running room correction.
4. Use the AV processor to select suitable loudspeaker crossover points.
5. Run the processor’s measurement and calibration routine where provided.
6. Check the resulting subwoofer level, distance and crossover settings.
7. Use familiar film and music material to complete fine adjustment.

Automated calibration is a useful starting point, but final listening checks remain important. Excessive output can make dialogue and effects sound heavy, while insufficient output reduces scale and impact.

Single Subwoofer or Multiple HT/1003 MKII Units?

The HT/1003 MKII is not intended for vertical REL line-array stacking. Multiple units should be distributed around the room according to the requirements of the home cinema system.

REL HT/3D Home Cinema Systems

REL’s HT/3D approach uses multiple subwoofers to support different areas of a surround installation rather than relying entirely on one cabinet.

A Serie HT model can provide the main LFE impact, while additional compatible RELs support the front loudspeakers, centre channel or surround region.

The exact number, type and position of subwoofers should be planned around the room, speaker layout and listening priorities.

HT/1003 MKII, HT/1205 MKII or HT/1510 Predator II?

Line-Grained Composite Cabinet

The cabinet body is finished in a horizontally oriented line-grained black composite.

Its 15mm top plate receives five coats of hand-polished high-gloss black lacquer, with a discreet REL logo beneath the finished surface.

The combination gives the HT/1003 MKII a restrained appearance that works alongside contemporary televisions, cinema speakers and REL Serie T/x models.

Use a soft microfibre cloth for routine cleaning and avoid abrasive household cleaners.

System Matching

Browse our home cinema subwoofers , home cinema amplifiers , home cinema speakers , wireless accessories and subwoofer and system cables , or explore the REL range at Audio T .

Key Features

• Compact active subwoofer developed for home cinema
• Closed-box cabinet with front-firing active driver
• 250mm long-throw CarbonGlas cone
• Glass-fibre main cone with inverted carbon-fibre centre cap
• Steel driver chassis
• 24Hz low-frequency extension at minus 6dB
• 300W RMS Class D amplifier
• REL analogue PerfectFilter circuitry
• Protective analogue subsonic filter
• Electronic Set-Safe protection
• Stereo low-level RCA inputs
• Dedicated RCA LFE connection
• RCA outputs for compatible daisy-chain systems
• Variable 30Hz to 200Hz crossover
• 0 or 180-degree phase adjustment
• Standby and always-on operating modes
• Compatible with REL HT-Air MKII
• Suitable for single and multiple-subwoofer systems
• Line-grained black composite cabinet
• Hand-polished high-gloss top panel
• Three-year REL warranty, subject to current terms

Frequently Asked Questions