REL Tzero MKIII Compact Subwoofer

The REL Tzero MKIII is an ultra-compact active subwoofer developed for smaller music systems, active loudspeakers, television, gaming and modest home cinema installations.

It combines a down-firing 165mm aluminium long-throw driver with a 100W RMS Class D amplifier, sealed cabinet and low-frequency extension reaching 37Hz at the stated minus 6dB point.

The Tzero MKIII can operate as a single subwoofer, as part of a stereo pair or within a discreet multi-subwoofer system where several compact cabinets are easier to accommodate than one larger model.

REL Performance in an Ultra-Compact Cabinet

The Tzero MKIII is the smallest and most affordable powered subwoofer in REL’s range.

It measures approximately 216mm wide, 241mm high and 260mm deep, allowing it to fit into rooms and systems where a conventional subwoofer may be impractical.

Its compact dimensions make it particularly useful with desktop systems, compact standmount speakers, active loudspeakers and smaller televisions.

Although the Tzero MKIII can produce surprisingly convincing bass for its size, customers requiring high playback levels or powerful deep-bass effects should consider a larger REL model.

165mm Aluminium Long-Throw Driver

The Tzero MKIII uses a single 165mm long-throw aluminium active driver.

The rigid aluminium cone helps the driver remain controlled during rapid movement while keeping the assembly sufficiently light to respond quickly to music.

Its long-throw suspension allows greater movement than would normally be expected from a driver of this size, helping the Tzero MKIII produce useful bass extension from its small cabinet.

A steel chassis provides a stable mechanical foundation for the cone, voice coil and suspension.

Down-Firing Driver Arrangement

The active driver is positioned beneath the cabinet and directs low-frequency energy towards the floor.

This helps distribute bass throughout the room while allowing the front and side panels to remain free from a visible driver or conventional grille.

The down-firing arrangement also gives the Tzero MKIII flexibility when positioning it beside furniture or close to compact loudspeakers.

Closed-Box Cabinet

The Tzero MKIII uses a sealed cabinet with no reflex port or passive radiator.

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

The absence of a reflex port also removes the possibility of port airflow noise during demanding bass passages.

The compact enclosure is designed to prioritise speed, musical integration and ease of placement rather than maximum output.

37Hz Low-Frequency Extension

REL specifies low-frequency extension to 37Hz at minus 6dB.

This allows the Tzero MKIII to reproduce bass information that many compact loudspeakers, desktop speakers and small active systems cannot deliver with useful output.

It can add greater weight and realism to bass guitar, drums, piano, orchestral music, television, games and compact home cinema systems.

Room size, positioning, floor construction and the listening position will all influence the extension and output achieved in practice.

100W NextGen Class D Amplifier

A 100W RMS NextGen Class D amplifier powers the aluminium driver.

The efficient amplifier design allows REL to provide useful output and control without requiring a large power supply or increasing the cabinet size unnecessarily.

The amplifier uses input filters, crossovers and limiting principles derived from REL’s larger models.

Its output is rated as continuous RMS power rather than a short-duration peak figure.

Fast Analogue Filtering

The Tzero MKIII uses REL’s fast input filtering to blend its output with the main loudspeakers.

The High Level and low-level signal paths pass through an adjustable low-pass crossover, allowing the upper limit of the subwoofer’s output to be matched to the natural roll-off of the speakers.

The system is designed to preserve timing and help the Tzero MKIII integrate without drawing attention to itself as a separate sound source.

The Tzero MKIII does not include digital room correction. Positioning, phase, crossover and level should be adjusted carefully by ear or with suitable room-measurement equipment.

Fully Electronic Protection

REL’s electronic Set-Safe protection monitors the amplifier during operation.

Additional protection is provided against DC faults and output short circuits.

These systems operate automatically but do not replace correct installation, ventilation and connection practices.

REL High Level Connection

REL’s preferred connection for many conventional stereo systems is the supplied High Level Neutrik Speakon cable.

This receives the same signal and sonic character being delivered by the main amplifier to the loudspeakers.

The main speakers remain connected directly to the amplifier and continue to receive their normal full-range signal. The Tzero MKIII is added alongside them and adjusted to support their natural low-frequency roll-off.

A nominal 10-metre Neutrik Speakon High Level cable is supplied with the subwoofer.

Low-Level RCA Input

A single RCA low-level input allows the Tzero MKIII to receive a mono signal from a suitable pre-amplifier, integrated amplifier, processor or active loudspeaker system.

The source must provide a suitable variable output that follows the main system volume.

Low-level connection can be particularly useful with active speakers and equipment that does not permit a suitable High Level connection.

The low-level input shares the Tzero MKIII’s Hi/Low Level gain and crossover controls with the High Level input.

Dedicated RCA LFE Input

A separate RCA LFE input connects to the subwoofer output of a compatible AV receiver, surround processor, television system or soundbar.

This carries the dedicated low-frequency effects channel used by film, television, concert and multichannel game soundtracks.

The LFE input has its own level control and operates independently from the High Level or low-level music connection.

Bass management, loudspeaker crossover points, delay and channel level can normally be configured from the connected home cinema processor.

Simultaneous Music and Cinema Connection

The Tzero MKIII can use its High Level or low-level input for music while also remaining connected to the dedicated LFE output of a home cinema processor.

The two signal paths provide separate level adjustment, allowing the subwoofer to integrate naturally with the main loudspeakers during stereo listening while reproducing the dedicated .1 channel during films.

This arrangement is particularly useful where the same main loudspeakers and amplifier are shared between a stereo system and compact home cinema installation.

Separate Hi/Low and LFE Level Controls

The Hi/Low Level control adjusts the output produced from the High Level Speakon or low-level RCA input.

The separate .1/LFE Level control adjusts the output produced from the dedicated home cinema input.

These independent controls allow the Tzero MKIII to maintain one setting for music and another for home cinema without requiring repeated adjustment when changing source.

Variable Crossover Adjustment

The rear crossover control adjusts the upper frequency reproduced through the High Level and low-level signal paths.

It should be set so that the Tzero MKIII supports the natural low-frequency roll-off of the main loudspeakers without creating an obvious overlap in the upper bass.

The crossover does not control the dedicated LFE input because the home cinema processor normally handles the relevant filtering and bass management.

An excessively high setting can make the system sound thick or reveal the location of the subwoofer, while an excessively low setting may leave a gap between the speakers and subwoofer.

0 or 180-Degree Phase Adjustment

A two-position phase switch helps align the movement of the Tzero MKIII driver with the main loudspeakers at the listening position.

The correct setting is normally the one that produces the strongest, fullest and most coherent bass.

Phase should be established before completing the final crossover and gain adjustment.

The best setting depends on the room, loudspeaker position, subwoofer position and listening seat.

Automatic Standby Operation

The Tzero MKIII includes an automatic standby circuit designed to respond reliably to low-level incoming signals.

When no suitable signal is detected, the amplifier can enter a lower-power state and reactivate when playback resumes.

Very low source levels, unusual gain structures or unsuitable connections may affect automatic activation.

HT-Air MKII Wireless Compatibility

REL currently lists the Tzero MKIII as compatible with the optional REL HT-Air MKII wireless system .

HT-Air MKII can transmit a low-level RCA or dedicated LFE signal using an uncompressed 5.8GHz wireless connection.

The transmitter connects to the source equipment, while the separate receiver connects to the appropriate RCA input on the Tzero MKIII.

This can avoid the need to run a long RCA cable around the room, although the subwoofer, transmitter and receiver continue to require their appropriate power connections.

Bassline Blue High Level Cable

A standard 10-metre High Level cable is supplied with the Tzero MKIII.

The optional REL Bassline Blue High Level cable provides an upgraded connection for compatible amplifiers and REL subwoofers.

Bassline Blue is available in different lengths and connection versions, including configurations developed for compatible Naim amplifiers.

Confirm the correct cable version and amplifier wiring arrangement before ordering.

Positioning the REL Tzero MKIII

Begin with the Tzero MKIII positioned along the same wall as the main loudspeakers.

A corner position can increase output and low-frequency extension, while moving the cabinet away from the corner may reduce excessive room-related bass.

Small changes in position can make a significant difference, so the final location should be established by listening rather than appearance alone.

Avoid enclosing the subwoofer tightly within furniture or positioning it where the down-firing driver, controls or amplifier ventilation can be obstructed.

Initial Stereo Setup

1. Place the Tzero MKIII along the same wall as the main loudspeakers.
2. Switch off the complete system before making any connections.
3. Connect the supplied High Level cable or a suitable low-level RCA interconnect.
4. Begin with conservative crossover and Hi/Low Level settings.
5. Select the phase setting that produces the strongest and most coherent bass at the listening position.
6. Adjust the crossover so the Tzero MKIII supports the natural roll-off of the main loudspeakers.
7. Increase the Hi/Low Level control until the additional bass is clearly audible.
8. Reduce the level slightly until the subwoofer no longer draws attention to itself.
9. Complete the setup using familiar music from the normal listening position.

Initial Home Cinema Setup

1. Connect the AV receiver or processor’s subwoofer output to the dedicated RCA LFE input.
2. Set the Tzero MKIII .1/LFE Level control conservatively.
3. Configure suitable loudspeaker crossover points within the processor.
4. Run the processor’s measurement and room-correction procedure where provided.
5. Review the measured subwoofer level, distance and crossover settings.
6. Check that bass effects do not overpower dialogue or the main loudspeakers.
7. Complete the setup using familiar film, television and music material.

Single Tzero MKIII or Stereo Pair?

Two subwoofers are not used purely to make the system louder. Correctly positioned and adjusted, a stereo pair can improve low-frequency balance, soundstage scale and integration with the main loudspeakers.

Can the Tzero MKIII Be Vertically Stacked?

The Tzero MKIII is not designed for vertical REL line-array stacking.

Its cabinet, feet and down-firing active driver require conventional upright floor placement with clear operating space beneath the enclosure.

Multiple Tzero MKIII subwoofers should instead be positioned separately around the room according to the requirements of the system.

REL 3D Home Cinema Systems

REL’s 3D approach uses several subwoofers to support different areas of a surround system rather than relying entirely on one cabinet.

A dedicated Serie HT model may handle the main LFE channel, while compact REL subwoofers support the front loudspeakers, centre speaker or rear region.

The small dimensions of the Tzero MKIII can make it useful for selected support roles where a larger cabinet would be difficult to accommodate.

The number and position of subwoofers should be planned around the room, speaker layout, processor and intended listening levels.

REL Tzero MKIII, T/5x or T/7x?

All three models provide REL High Level, low-level and dedicated LFE inputs.

The most appropriate model should be selected according to room size, loudspeaker capability, required playback level and available floor space rather than price or amplifier output alone.

Compact Rounded Cabinet

The Tzero MKIII uses a compact cabinet with clean surfaces and softly rounded edges.

Its down-firing driver allows the front and side panels to remain free from a visible cone or conventional grille.

The simple cabinet design helps the subwoofer sit discreetly beside furniture, compact loudspeakers or a desktop system.

Piano Black and Gloss White Finishes

The Tzero MKIII is available in Piano Black Lacquer or Gloss White Lacquer.

Five coats of gloss lacquer create a refined surface intended to complement contemporary loudspeakers, furniture and system components.

Use a clean, soft microfibre cloth for routine care and avoid abrasive household cleaners that could mark the lacquer.

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

• Ultra-compact REL active subwoofer
• Closed-box cabinet with down-firing active driver
• 165mm long-throw aluminium cone
• Steel driver chassis
• No passive radiator or reflex port
• 37Hz low-frequency extension at minus 6dB
• 100W RMS NextGen Class D amplifier
• Fast REL input filtering and crossover circuitry
• High Level Neutrik Speakon input
• Single low-level RCA input
• Dedicated RCA LFE input
• Separate Hi/Low Level and .1/LFE gain controls
• Variable low-pass crossover for High Level and low-level inputs
• 0 or 180-degree phase adjustment
• Automatic standby operation
• Compatible with HT-Air MKII for low-level or LFE wireless connection
• Not compatible with REL Arrow
• Supports simultaneous music and home cinema connection
• Suitable for single and stereo-pair installations
• Suitable for discreet multi-subwoofer systems
• Piano Black or Gloss White finish
• Five-coat gloss lacquer finish
• Fully electronic Set-Safe protection
• DC fault and output-short protection
• Three-year REL warranty, subject to current terms

Frequently Asked Questions