Rel Acoustics T9i review: a powerful, lively and generous subwoofer, ideal for both hi-fi and home theater


Mis à jour le 6 March 2021.

The Rel T9i is the flagship of the Welsh manufacturer’s Ti subwoofer range. This passive subwoofer is equipped with a 10” (25.4cm) driver and passive radiator. The Rel Acoustics T9i features powerful 300-watt RMS amplification and an extended low frequency response that goes as low as 28Hz. Sold for 1475 euros, this subwoofer is suitable for both hi-fi listening and home theater systems. It is designed to accompany compact and floorstanding speakers and to produce tight, deep and powerful bass, even in a large room. 

The Rel Acoustics T9i subwoofer is equipped with a 10” driver and passive radiator. It has a power output of 300 watts RMS.

Rel Acoustics T9i: the brand

The Rel Acoustics company is based in Bridgend in Wales and was founded by Richard Edmund Lord in 1990. Dissatisfied by the subwoofers available at the time, he decided to build a better quality subwoofer himself. 

One of the keys to the success of Rel Acoustics subwoofers over competing models is the systematic use of a high level connection with the amplifier. It is powered by the signal from the final output stage of the amplifier, the same one that drives the speakers, which ensures a very consistent overall sound signature and allows the subwoofer to be connected to any amplifier. Rel Acoustics has used a specific high level input since 1990. All Rel Acoustics subwoofers equipped with a high level input use a professional standard Speakon connector and come with a dedicated cable. The Speakon connector is valued for its robustness, ease of use and anti-pullout locking system.

All Rel Acoustics subwoofers equipped with a Speakon standard high level input come with a dedicated cable to connect to the amplifier’s speaker terminals.

Another major advantage of Rel Acoustics subwoofers is their high current amplifier. Current (intensity), not voltage, is the key element to set the subwoofer’s large drivers in motion. Since 1998, the Welsh engineers have made sure that the integrated amplifiers in Rel Acoustics subwoofers produce a high level of current. This ensures that they reproduce not only the attack and body of a note, but also the echoes during the decay of a sound. Not all integrated subwoofer amplifiers are created equal, and the amplifiers of Rel Acoustics subwoofers are specifically designed to reproduce the lowest notes.

A large passive radiator tasked with cooling the electronic components and the power supply of the 300-watt RMS amplifier are located at the back of the Rel Acoustics T9i.

A new era for Rel Acoustics began in 2005 when it was acquired by John Hunter and Donald Brody. Almost immediately, they began to build upon the philosophy driving the creation of Rel Acoustics products by improving the design, the mechanical structure, the electronic circuits and the quality of the drivers. Compared to previous generations, the new Rel subwoofers were more powerful, faster and offered better value.

In 2007, the NaturalSound crossover was introduced to ensure seamless integration of the main speakers with Rel Acoustics subwoofers. Simple and intelligently designed to eliminate the sound bumps and gaps that occur with competing subwoofers, these filters are exceptionally fast, ensuring excellent responsiveness from the subwoofer.

Since 2010, the cabinets of Rel Acoustics subwoofers have been equipped with very robust bracing. Similar in design to the braces found in certain musical instruments, their function is to eliminate cabinet resonance. This design is much more effective than simple reinforcements that can generate noise and turbulence, sometimes resulting in blurred musical details.
Inspired by the design of musical instruments, the bracing in Rel Acoustics subwoofers (here the Rel Acoustics G1 Mark II) ensures perfect cabinet stability without coloring the sound or generating turbulence.

Efficient bracing eliminates baffle resonance that can negatively impact the correct pitch of instruments far outside the bass region. The Welsh manufacturer uses sophisticated bracing and improved materials such as laminated wood braces for the Rel Acoustics Reference Series subwoofers (the top of the range). 

Today, Rel Acoustics is recognized across the globe as a leading brand in the premium audiophile subwoofer market. The Welsh company offers several ranges of subwoofers to suit all budgets and uses. 

Rel Acoustics T Series and T/i Series (hi-fi and home theater)

Rel Acoustics HT Series (home theater)

Rel Acoustics S Series (hi-fi and home theater)

Rel Acoustics Reference Series (hi-fi and home theater)

Rel Acoustics T9i: packaging & accessories

The Rel Acoustics T9i subwoofer comes with everything you need to get it up and running, notably a cable to connect it to your amplifier’s speaker terminals. 

The Rel Acoustics T9i subwoofer comes with a 10 meter long high level connection cable.

Measuring about 10 meters, the cable is equipped with a Speakon connector at one end and three stripped wires at the other. There is also a power cable, a pair of fabric gloves for handling the subwoofer without leaving fingerprints, the acoustic fabric grille and the user manual.

Rel Acoustics T9i: presentation


As soon as we took it out of the box, we were very impressed by the Rel Acoustics T9i subwoofer’s deep black lacquered finish. However, the drawback of this finish is that the shiny surface attracts fingerprints. Thankfully, the manufacturer provides a pair of fabric gloves!

The Rel Acoustics T9i subwoofer’s lacquered finish is beautiful, but be careful of fingerprints!

With or without the acoustic grille, this Rel Acoustics subwoofer looks great and won’t stick out in your living room or dedicated home theater room. The passive radiator’s white and silver cone that is decorated with the brand’s logo gives the subwoofer a distinctive look and remains slightly visible through the acoustic fabric grille.

The Rel Acoustics T9i’s passive radiator isn’t quite as visible once the grille is in place.

However, the silver logo on the top of the cabinet and the silver feet, which are also decorated with the letters “R E L”, are a little too ostentatious for our taste. We would have preferred a more understated look.

The “REL” logo is omnipresent on the feet of the Rel Acoustics T9i subwoofer.

300 watts, 10” driver + passive radiator

The Rel Acoustics T9i subwoofer’s 10” driver is down-firing. Its huge, half-roll surround provides extensive excursion.

The Rel Acoustics T-9i subwoofer is the flagship model in the Welsh manufacturer’s T/i Series. It features a 10” down-firing driver paired with a front-firing passive radiator. The latter increases the acoustic pressure and the bass level produced by the main driver. Powered by an amplifier with an output power of 300 watts RMS, it is equipped with a long-throw surround so that it can move a considerable amount of air. As a result, the Rel Acoustics T9i subwoofer provides an extensive bass response that reaches 28Hz.

The Rel Acoustics T9i’s passive radiator is situated on the front of the subwoofer and also features a long-throw surround.

High level, low level and LFE inputs

The Rel Acoustics T-9i subwoofer’s connectors include a low level input (RCA mono), an LFE input (RCA mono), a high level stereo input (Speakon) and a dedicated connector for the Rel Arrow module (9-pin serial port) to stream sound wirelessly. As with all of its subwoofers, Rel Acoustics has used a Speakon connector for the high level input of this model. The manufacturer highly recommends using the high level connection because it allows the same signal to be sent to both the speakers and the subwoofer, ensuring a consistent soundstage.

The Speakon connector (High Level Input) on the Rel Acoustics T9i subwoofer is intended to receive the signal from the speaker terminals of the amplifier to which it is connected. A dedicated cable is supplied by the manufacturer.

A 10 meter long dedicated cable is included with the Rel Acoustics T-9i subwoofer, along with a detailed user manual illustrating the different connections to use depending on the type of amplifier you wish to connect.

Settings and power supply

On the rear panel of the Rel Acoustics T9i subwoofer are the different settings controls: phase (0 or 180°), high cutoff frequency (crossover from 30 to 120Hz) and gain. Well designed, the gain for the high level and low level inputs is separate from the gain for the LFE input so that there are two different settings for hi-fi and home theater use. 

The Rel Acoustics T9i subwoofer’s rear panel features the connectors, the settings controls and the aluminum passive radiator that keeps the integrated amplifier cool.

Lastly, the power switch, which features a power-on indicator diode, is accompanied by a toggle switch that lets you decide whether to leave the subwoofer turned on or if you want it to automatically switch to standby mode when no signal is detected.

Above the standard power switch, a metallic toggle switch allows you to activate the power/automatic standby mode.

Key specifications


  • Sturdy cabinet with internal bracing
  • Lacquered finish


  • 10” long-throw, down-firing driver
  • 10” passive radiator on the front panel


  • Class AB amplification module
  • Output power: 300 watts RMS
  • Toroidal transformer


  • Low frequency extension: 28Hz (-6dB)
  • High level input impedance: 150 k
  • Low level input impedance: 10 k
  • LFE .1 input impedance: 10 kohms


  • High cutoff frequency: 30 – 120Hz
  • Phase: switch, 0 – 180°
  • Gain: 80dB, separate for the high/low level inputs and LFE input
  • Power/automatic standby switch


  • Low level input (mono, RCA)
  • High Level input (stereo, Neutrik Speakon)
  • LFE .1 input (RCA)
  • Port for a Rel Arrow wireless transmission module


  • Dimensions (W x H x D): 330 x 387 x 407mm (including feet, connectors and buttons)
  • Weight: 18.7kg


  • Power cable
  • Speakon stereo connection cable (10m)
  • User manual
  • Pair of fabric gloves

Rel Acoustics T9i: listening conditions

The Rel Acoustics T9i subwoofer has been in our listening room for a few months now. We have been able to test it with hi-fi setups and during home theater sessions, together with various speakers, stereo amplifiers and A/V receivers.

We were able to test the Rel Acoustics T9i subwoofer with the Marantz PM7000N connected amplifier, along with the Elipson Prestige Facet 8B and Focal Chora 826 speakers.

In hi-fi, we enjoyed the subwoofer’s qualities with the Marantz PM7000 and Atoll IN200 amplifiers, along with the Focal Chora 826 floorstanding speakers and the Elipson Prestige Facet 8B compact speakers. We used the high level connection (Speakon input on the subwoofer) with the included cable for these installations. To do this, we simply connected the red and yellow wires to the positive terminals of the amplifier’s two speaker outputs before connecting the black wire to one of the two negative terminals. 

The Speakon connector cable that is included with the Rel Acoustics T9i subwoofer lets you easily connect it to the speaker terminals on a stereo amplifier (here the Atoll IN200 Signature).

We then adjusted the level of the subwoofer (High/Low Level knob) to match that of the speakers. Lastly, we adjusted the subwoofer’s high cutoff frequency by positioning it slightly above the low cutoff frequency of the speakers, listening to make sure that there wasn’t too much bass nor too little. 

For home theater, we enjoyed the Rel Acoustics T9i subwoofer with both the Onkyo TXRZ840 and NAD T778 A/V receivers, connected to an Elipson Prestige Facet speaker pack, but also the Focal Chorus 726 HCM speakers. We connected the amplifier’s LFE output to the subwoofer’s .1/LFE input using a subwoofer cable. We also set the level of the subwoofer (.1/LFE Level knob) to match that of the speakers. The cutoff frequency was adjusted using the automatic calibration, accessible via the interface of the A/V receiver.

Paired with the speakers in the Focal Chorus 726 HCM pack, the Rel Acoustics T9i subwoofer allowed us to experience all of the tension during the action scenes in Mad Max: Fury Road.

Rel Acoustics T9i: listening impressions

High fidelity

Whether we were using a pair of compact speakers such as the Elipson Prestige Facet 8Bs or floorstanding speakers like the Focal Chora 826, it didn’t take long to notice the advantage of associating them with the Rel Acoustics T9i subwoofer. Naturally, the extension and presence in the lows were more impressive, but the whole soundstage also benefited from the addition of the subwoofer. With more presence in the lows, the midrange seemed to gain texture, while the highs were clearer and seemed more detailed. The music was reproduced more adeptly than it was with just the speakers and had more substance. 

The Rel Acoustics T9i subwoofer is particularly well suited to high fidelity listening sessions, even with floorstanding speakers such as the Focal Chora 826s that are already equipped with dedicated woofers.

The stereo image and the depth of the soundstage also benefited from the extra details the Rel Acoustics T9i subwoofer provided in the low end of the spectrum. The spatial presentation had more dimension and the music had more room to breathe. Highly responsive, the Rel Acoustics subwoofer was seamlessly integrated as it was powered by the same signal as the speakers. There were no delays, and the attacks were powerful. The 300-watt amplifier controlled the driver’s cone steadily and the passive radiator followed the same tempo. 

The Rel Acoustics T9i was in its element with bass-heavy tracks like Never Undo (Morcheeba). It delivered powerful, full and nuanced lows that effectively rhythmed the track. On acoustic recordings like The Love That You Had (Tracy Chapman), the subwoofer was just as beneficial as it contributed to the credibility of the percussion (better impact) and the bassline (more depth). The sound gained realism and density, with rich and nuanced bass.

Home theater

The Rel Acoustics T9i subwoofer also provided excellent performance in home theater configurations and was remarkably explosive. Its 300 watts of power were perfectly utilized and showed no sign of faltering. With Peter Weir’s Master & Commander, the cannon fire was powerful and ultra-realistic. The T9i had a ball and, much to our delight, reproduced every cannon blast with thunderous infra-lows.

With the support of the Rel Acoustics T9i, the exceptional soundtrack of the movie Master & Commander sounded extremely realistic.

On Mad Max: Fury Road, whose soundtrack isn’t lacking in epic scores either, the Rel Acoustics subwoofer greatly accentuated every moment of tension. The deep bass produced by the T9i rhythmed the action scenes with energy and intensity. The engine noises were believable (the purr of the V8 in the hero’s Ford for example) and the explosions were always very spectacular.

We thoroughly enjoyed the Rel Acoustics T9i subwoofer with Mad Max’s explosive soundtrack.

Note that the subwoofer is very responsive and comes out of automatic standby mode quick enough not to miss any explosions.

Rel Acoustics T9i: compared to…

Dynaudio Sub 3: equipped with the same output power and a similarly sized driver, this Dynaudio subwoofer features an elegant satin finish. In practice it proves to be very responsive and provides lows without any lag or distortion thanks to its closed structure that optimizes its transient response. This portless design and its slightly smaller footprint also make it easier to install than the Rel model. Unfortunately, it isn’t equipped with a high level input. Consequently, you will need an amplifier with a preamplified SUB output to enjoy the Dynaudio Sub 3 during hi-fi listening sessions. 

B&W PV1D: a part of the British manufacturer’s catalog since 2012, the B1W PV1D continues to impress with its bold design, matched by an equally impressive acoustic performance. This closed subwoofer with its spherical cabinet is equipped with two 8” drivers powered by a 400-watt amplifier. The lows are deeper and more intense than those provided by the Rel subwoofer, which is tighter and “drier”. 

Rel Acoustics T9i: conclusion

The Rel Acoustics T-9i offers significant extension in the low end of the spectrum, providing music with substance and fully harnessing the LFE channel in movie soundtracks. The large emissive surface area of the driver and 10” passive radiator provides significant acoustic pressure during action movies. Dense, rich and deep, the lows produced by this subwoofer are also precise and nuanced. The 300-watt amplification controls the moving components of the subwoofer perfectly, with an excellent sense of rhythm and remarkable responsiveness which also allows this model to be used for purely hi-fi listening sessions. 

The Rel Acoustics T9i subwoofer is a great match for a pair of compact speakers for hi-fi listening. It is also suitable for home theater use.

With the Rel Acoustics T-9i, the Welsh manufacturer illustrates its expertise in passive enclosures. Powerful and responsive, this subwoofer is perfect for enhancing the realism of the soundstage and for bringing vitality to both hi-fi and home theater sessions.

What we liked

  • The solid and deep lows
  • The responsiveness in hi-fi and the explosiveness in home theater
  • The size, which makes it easy to position in a room

What we would have liked

  • For the feet to have been more understated

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Traductrice et rédactrice avec des goûts très éclectiques en matière de musique et de cinéma. Lorsque je ne suis pas au travail, vous pouvez me retrouver en train de regarder “Lost in Translation” de Sofia Coppola pour la centième fois, ou d’écouter un disque de David Bowie, Kate Bush, Joy Division ou Daft Punk sur ma platine Rega Planar 1. Étant d’origine britannique, je suis également adepte de séries à l’humour absurde comme Monty Python’s Flying Circus et The Mighty Boosh !


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