REL HT-Air MKII Wireless Subwoofer System

The REL HT-Air MKII is a wireless transmitter and receiver system developed for carrying stereo low-level or dedicated home cinema LFE signals to a compatible REL subwoofer.

It allows the subwoofer to be positioned where it performs best without requiring a long RCA cable to be routed beneath carpets, around doorways or across the listening room.

The system uses REL’s dedicated 5.8GHz wireless protocol rather than conventional Bluetooth or home Wi-Fi, providing a fast and stable connection designed specifically for low-frequency audio.

Greater Freedom When Positioning a Subwoofer

Subwoofer placement should be determined by the acoustics of the room rather than the nearest available signal connection.

The HT-Air MKII allows the transmitter to remain beside the amplifier, active loudspeakers or home cinema processor while the receiver is positioned beside the subwoofer.

Only the audio signal is transmitted wirelessly. The subwoofer, transmitter and receiver continue to require their appropriate power connections.

Dedicated 5.8GHz Wireless Transmission

HT-Air MKII uses REL’s third-generation 5.8GHz wireless technology.

The dedicated connection is designed for continuous, real-time transmission of music and film audio without relying on Bluetooth or the household Wi-Fi network.

This avoids the additional setup, network traffic and compression commonly associated with general-purpose wireless audio systems.

Uncompressed Low-Frequency Audio

The wireless signal is transmitted without data compression, helping preserve the dynamics and timing of the original low-frequency information.

This is particularly important during sudden film effects, bass transients and musical passages where excessive processing or delay could make the subwoofer sound disconnected from the main system.

REL describes the resulting performance as approaching that of a high-quality wired connection when the HT-Air MKII is installed correctly.

Approximately 17ms Response

REL specifies a response time of approximately 17 milliseconds.

This low delay helps the subwoofer remain closely aligned with the main loudspeakers during film, music and gaming.

The connected AV receiver or surround processor may also provide subwoofer-distance and delay adjustment, which should be checked after installing the wireless system.

Up to 12 Metres Wireless Range

REL specifies an effective wireless distance of approximately 12 metres, or 40 feet, with a clear line of sight.

The practical range may be reduced by walls, furniture, metalwork, equipment cabinets and competing wireless devices.

For the most reliable connection, avoid hiding either unit inside a metal cabinet or placing it immediately beside equipment that produces strong wireless interference.

Home Cinema LFE Connection

The HT-Air MKII can transmit the mono LFE signal from a compatible AV receiver, surround processor, soundbar or active cinema system.

For this arrangement, the source’s subwoofer output connects to the right RCA input on the transmitter.

The right RCA output on the receiver then connects to the LFE input on the compatible REL subwoofer.

Bass management, crossover frequency, level and delay are normally controlled from the connected home cinema processor.

Stereo Low-Level Connection

The left and right RCA inputs can receive a stereo low-level signal from a compatible pre-amplifier, integrated amplifier, active loudspeaker system or other source with suitable variable outputs.

Both RCA outputs on the receiver then connect to the corresponding low-level inputs on the subwoofer.

This arrangement allows the HT-Air MKII to support suitable two-channel systems as well as dedicated home cinema installations.

Simple Automatic Pairing

The transmitter and receiver are programmed to identify one another and should pair automatically after they have been connected and powered.

A solid status light on both units indicates that the wireless connection has been established.

If they do not pair automatically, the pairing button on the receiver should be pressed until its light flashes, followed by the pairing button on the transmitter.

Once paired successfully, the status lights remain continuously illuminated. The pairing is retained when the units are unplugged.

Home Cinema Setup

1. Switch off the AV system and subwoofer before making any connections.
2. Connect the processor’s subwoofer output to the transmitter’s right RCA input.
3. Position the receiver close to the compatible REL subwoofer.
4. Connect the receiver’s right RCA output to the subwoofer’s LFE input.
5. Connect the supplied power adaptors to the transmitter and receiver.
6. Switch on the subwoofer and associated equipment.
7. Check that the pairing lights remain continuously illuminated.
8. Run the processor’s room-correction procedure where provided.
9. Review the resulting subwoofer level, crossover, distance and delay settings.
10. Complete the setup using familiar film and music material.

Stereo Low-Level Setup

1. Confirm that the amplifier, pre-amplifier or active speakers provide suitable variable left and right RCA outputs.
2. Switch off the complete system before connecting any cables.
3. Connect the source’s left and right outputs to the corresponding transmitter inputs.
4. Connect the receiver’s left and right outputs to the compatible subwoofer’s low-level inputs.
5. Connect both supplied power adaptors.
6. Switch on the source equipment and subwoofer.
7. Confirm that the transmitter and receiver have paired.
8. Adjust the subwoofer’s crossover, level and phase controls to suit the main loudspeakers.
9. Complete the installation by listening from the normal seating position.

Substantial Cast Acrylic Cases

The transmitter and receiver are housed in compact cast acrylic cases finished in gloss black.

Their deliberately substantial construction helps prevent the units from being pulled out of position by the weight or tension of connected RCA and power cables.

Each case receives five coats of hand-applied acrylic lacquer, giving the compact accessories a finish designed to complement REL’s subwoofer range.

Transmitter Connections and Controls

• Left RCA input for stereo low-level connection
• Right RCA input for stereo or mono LFE connection
• Pairing button
• Wireless status indicator
• 5V DC power input

Receiver Connections and Controls

• Left RCA output for stereo low-level connection
• Right RCA output for stereo or mono LFE connection
• Pairing button
• Wireless status indicator
• 5V DC power input

Status Light Operation

Compatible REL Subwoofers

HT-Air MKII is designed principally for REL Serie HT subwoofers and other compatible models equipped with suitable RCA low-level or LFE inputs.

Connection compatibility should always be checked before purchase, particularly when using an older REL model, an active loudspeaker system or a subwoofer from another manufacturer.

HT-Air MKII or Airship II?

Placement Guidance

Place the transmitter close enough to the amplifier or processor for the chosen RCA cable to connect without tension.

The receiver should sit close to the subwoofer while remaining accessible for power, pairing and status checks.

Avoid placing either unit directly on top of hot-running equipment, close to water or within a tightly enclosed metal cabinet.

Do not stretch, sharply bend or trap the RCA and power cables beneath furniture.

Care and Cleaning

Use a slightly damp, but not wet, soft cloth to remove dust from the gloss acrylic cases.

Do not place drinks or other liquids on top of either unit.

Avoid abrasive cleaners and dry dusting cloths that could mark the gloss finish.

System Matching

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

Key Features

• Wireless subwoofer transmitter and receiver system
• Designed principally for REL Serie HT subwoofers
• Supports stereo low-level RCA transmission
• Supports mono home cinema LFE transmission
• Dedicated third-generation 5.8GHz wireless technology
• Uncompressed low-frequency audio transmission
• Approximately 17ms response time
• Effective range of approximately 12 metres with clear line of sight
• Simple automatic or manual pairing
• Pairing is retained after the units are unplugged
• Separate transmitter and receiver status indicators
• Left and right RCA inputs on the transmitter
• Left and right RCA outputs on the receiver
• Right channel used for mono LFE operation
• Substantial cast acrylic cases
• Five coats of hand-applied acrylic lacquer
• Compact gloss-black finish
• Two power adaptors supplied
• Two 2-metre RCA cables supplied
• Suitable for home cinema and compatible stereo systems
• Three-year REL warranty, subject to current terms

Frequently Asked Questions