REL T/7i Subwoofer and Arrow Wireless Module Review

Hop To

REL wants you to take it to a higher level- inputs we mean

by Ed Selley Oct 17, 2017 at 7:40 AM

  • Home AV review


    REL T/7i Subwoofer and Arrow Wireless Module Review
    SRP: £849.00

    What is the REL T/7i?

    The REL T7i is a compact subwoofer and the middle of three T Series models. It is an extensively revised version of the T/7 model that we reviewed some years ago. It also continues to embody a different approach to the business of sub bass creation. REL sees itself as a little different to many other companies that build subwoofers. While they have adapted to the growth in multichannel audio – which has driven a considerable demand for subwoofers – the company first and foremost considers themselves to be a producer of HiFi equipment.

    This means that the T/7i is designed and equipped slightly differently to many rivals at the price – as we shall cover – but not to the extent that REL feels that the T/7i can’t ‘cut it’ as a normal subwoofer to be used in an AV system. Nonetheless, the design leanings of REL are clearly visible in the T/7i and there is no shortage of burly looking rivals vying for your attention from various rivals so does it work?

    To throw another variable into the mix, while the REL is designed with a view to a certain level of purism, it also has a rather unexpected convenience feature. If you are wondering about where best to place such a device and concerned that this doesn’t match with where you can physically run a signal cable, REL has a solution. More intriguingly still, REL says this solution doesn’t have any effect on the design ethos of the T/7i itself. There’s a lot to unpick here so we’ll crack on and see how the T/7i stacks up.


    REL T/7i  Specifications
    The T/7i is described as a revision to the original T/7 but the nature and scope of these changes is sufficiently great that nobody would have batted an eyelid at it being described as a new model. The basic premise of the T/7i is the same as the T/7 in that it is a sealed cabinet design which uses an active driver mated to a passive radiator. The most significant revision between old and new is that the position of these drivers has been reversed. The 8 inch active driver now faces forwards while the 10 inch radiator moves to the underside.

    In principle this makes a fair degree of sense. While a forward firing driver places some restrictions in placement terms over a downward firing one, it alleviates many of the issues of using such a device on a suspended floor – the energy from the passive radiator being somewhat lower than the driver – and, in many parts of the world, this is rather more useful than any slight loss of positioning flexibility.

    The material that the drivers have been made from have also been changed. They are still in essence made from paper but REL has delved into the business of paper composition and worked to create a driver that has less mass to it. This feeds into REL’s ongoing concern with the ‘speed’ with which the driver operates. Reducing the mass of the driver, reduces the amount of force required to start and in turn stop it. The driver can be moved more precisely and under a greater degree of control than would be the case if it was heavier and more inert. To give the driver a rigidity greater than that of a soggy paper plate, REL has then fitted a very large aluminium centre cap to the active driver. This acts as a stiffening component which doesn’t add much in the way of mass to the product.

    The cabinet these drivers are placed in has been thickened and strengthened. It is now made from inch thick sections of MDF and feels extremely solid to the touch. The feet are integral to the cabinet and are capped with a plastic screw fitting that seems to avoid them marking surfaces that they are placed on. Compared to some of the burlier American designs we have looked at in recent months, the T/7i feels less monolithic – it can be lifted without the nagging feeling that a hernia is only seconds away – but it still manages to come across as solid and inert.
    REL T/7i  Specifications
    It is the amplification and inputs of the T/7i where some of REL’s distinct design philosophies come into play. First up, on the amp plate you will encounter a heat sink which is a clear indicator that the amp used in the T/7i is a class A/B design rather than the more frequently encountered Class D. This generates 200 watts and is a gently evolved version of an amp used in many of the models dating all the way back to the very beginning of the company’s existence. The bald numbers don’t seem terribly exciting but in terms of current delivery and damping factor, there is much to be said for this approach.

    This amp will work with both a dedicated LFE input and a high level connection that is the REL trademark. This is intended to take the feed from an amplifier's speaker terminals and – crucially – because there is no high pass filter on this connection, it will impart some of the character of your amp to your sub bass. REL states in the manual that even if the LFE connection is in use, the high level connection should still be connected for optimal performance. While this is a contentious area, even if I did go about doing this I would have to switch my front speakers to large, which isn’t how my equipment is set up. It does – even if we leave subjectivity to one side for a minute – allow for the connection of the REL to a stereo amp with no preout. REL supplies a cable for this purpose and a conversation with REL HQ suggests that specialist ones are also available.

    The T/7i can also be supplied – as seen here – with the Arrow wireless module. This is a proprietary system developed by/for REL that consists of a USB powered sending unit and a self-powered receiver that attaches straight to an RS-232 connection on the rear panel of the T7i. REL says the system is lossless and has a maximum range of 13.7 meters. Pairing it is simple enough and once done, provided the T/7i has power running to it, it can be placed anywhere. Interestingly the receiver module has both LFE and high level connectors in a mirror of the input board. REL states that the benefits of the high level connection as laid out by them will still be experienced via wireless.


    REL T/7i  Design
    As is the now traditional incantation when discussing the aesthetics of subwoofers, there are limits to exactly what you can do with a solid box containing one or more hefty drivers. This being said, the T/7i feels like a special piece of equipment. The gloss black lacquer on the cabinet is applied to a very high standard and the REL badge on the top looks equally smart (and according to REL functions as part of the resonance control of the cabinet itself). While subwoofers don’t generally get put out on display, you could just about find justification for doing so with the T/7i. The level of overall build and finish is also extremely good and everything feels solid and carefully thought out.

    There’s a ‘but’ coming though. At £850, the REL feels fairly pricey for the specification on offer. Ignoring the amplifier power for a moment as this is a slightly different area, some aspects of the REL feel a little lightweight. There is an ongoing argument about what equipment is required with subs and what is pure window dressing but I would have liked to see a continuously variable phase control – arguing you can place the T/7i wherever you like doesn’t really stand up when you have to take into account keeping it in phase with the supporting speakers. I’d also potentially like at least the option of remote control.

    REL T/7i
    While subwoofers don’t generally get put out on display, you could just about find justification for doing so with the T/7i

    How was the T/7i tested?

    The REL was supplied as a pair of units and they were placed at the front of the room – one running with an Arrow wireless module and one connected directly to a Yamaha RX-A3040 AV receiver with Cambridge Audio 752BD Blu Ray, Sky HD and a Panasonic GT60 Plasma all connected to an IsoTek Evo 3 Aquarius mains conditioner. Supporting speakers were my Elipson Planet M satellites. Some stereo testing via the high level connection was undertaken via a Cambridge Audio 851A connected to a Chord Hugo2 and a pair of Acoustic Energy AE1 Classic speakers. Material used has included Blu Ray, scheduled and on demand TV and online services such as Netflix as well as lossless and high res FLAC and AIFF as well as Tidal and Spotify.

    Sound Quality – Multichannel

    REL T/7i  Sound Quality – Multichannel
    With the T/7i running at the front of the room on axis with the front speakers and running a 90Hz crossover, there are some immediate signs that the T/7i has some impressive qualities. Most notably, the integration that the REL offers between it and the Elipsons, even without the high level input in use, is seamless to the point of imperceptible. It is frequently impossible to work out what the T/7i is contributing until you switch it out of the circuit. If you have smaller speakers and will be dependent on a subwoofer to fill in all the time – and that means gently picking out the orchestral score for Victoria as much as it does delivering the thrills of movie night – the REL is a superb partner.

    Of course, when it is movie night, the performance of the T/7i is good with some small caveats. Firstly, if you absolutely must feel the full brunt of any impact and explosion in your lower intestine, this is probably not the device for you. REL quotes a lower figure of 30Hz and this can be comfortably exceeded in room but this isn’t a truly seismic device. There are some rather better bits of news though. The detail retrieval of the REL is extremely good. The various effects that make up the movement of tanks in Fury is delivered with real texture and an appreciable sense of the engine, tracks etc. This is bass as a fully developed aspect of the soundtrack and not a simple noise engine.

    The truly outstanding quality of the REL comes to the fore when you put on something like the final live performance in Whiplash. This isn’t seismic bass, it can be handled almost in its entirety by a large floorstander, but with a 90Hz crossover a huge amount of the drumming is given over to the REL and it excels. In terms of sheer transient speed, the REL is able to match the Eclipse TD520SW – which is still the most accomplished subwoofer I have ever tested. REL’s obsession with driver weight and effective mass might seem curious but it really does pay dividends.
    REL T/7i  Sound Quality – Multichannel
    So what happens if you add a second one? Doubling the radiating area and keeping them both on axis allows for the same SPL numbers to be achieved with both subs running at lower levels. Performance below 30Hz is definitely enhanced. There is also the potential to even out the response in room by positioning them (lack of phase correction not withstanding). The same speed and detail is retained though and this makes for a seriously impressive sub bass system. It is a fairly expensive one though. Even though the individual cabinets are fairly compact, collectively, they take up more room than a single large one (and need two mains leads, two sub outputs etc). This is an answer to a specific set of design challenges, not a one size fits all solution.

    The Arrow wireless system is genuinely impressive though. Using one T/7i via a standard wired connection and one via Arrow shows no performance difference or latency issues. It has proved completely bulletproof in the time it has been installed and this has included interrupting the power and other issues. £200 for the system isn’t cheap (and it needs power of its own) but it does work exactly as specified making the T/7i an impressive bit of kit.

    Sound Quality – Music

    REL T/7i  Sound Quality – Music
    When I reviewed the original T/7, I grudgingly conceded that, even as someone that isn’t a fan of using subs for music it was extremely good. The T/7i effectively builds on this. With a 55Hz crossover set on the sub to partner the AE1 Classics, the performance has the same seamless detailed and musical presentation that there was before but with an added dose of agility. The complex percussion line of The Comet is Coming’s Channel the Spirits are handled with enough speed and lack of overhang to be convincing and believable. There is a slight but perceptible sense of the character of the amp that helps bind the speakers and sub together that also helps.

    Inserting the Arrow system into the chain and continuing to use the high level connection does seem to continue to convey the basic character of the amp in the signal and – as with multichannel use – has no effect on latency. Adding the second sub and giving each T/7i its own specific channel further improves the separation and detail and gives well recorded material an additiona boost. Once again, it’s expensive (although not as expensive as a single Eclipse TD520) but it does deliver aspects of performance that a single hefty sub simply can’t do.

    REL T/7i
    In terms of sheer transient speed, the REL is able to match the Eclipse TD520SW – which is still the most accomplished subwoofer I have ever tested


    OUT OF


    • Exceptional agility and transient speed
    • Beautifully made
    • Arrow module is well implemented


    • Rivals at similar price can offer greater extension
    • No continuously variable phase
    • Fairly pricey with Arrow specified
    You own this Total 0
    You want this Total 1
    You had this Total 0

    REL T/7i Subwoofer and Arrow Wireless Module Review

    For many people reading this, the nature of how they use subwoofers and the on-paper numbers of the T/7i won’t make a huge amount of sense. When it comes to movie night, connected in a normal way and setup with any proficiency, the T/7i is good but not necessarily any better than subs at the same price or arguably even less. It’s attractive and well finished but it carries a premium price tag as a result of that.

    Some time with a pair of them does reveal some singular abilities though. If you run a sub all the time and with speakers that need a 50Hz and up crossover in particular, the REL is effortlessly integrated, controlled and detailed. It has an agility and nuance that most rivals struggle to get anywhere near and for music especially, it sits in a very select field indeed. The inclusion of the Arrow wireless system further improves the basic flexibility and makes this a very capable subwoofer indeed. If you can run two, their ability to create a rich and believable low end is very compelling. It’s a premium solution but the REL warrants recommendation due to the depth of talent it displays.

    Suggested retail price when reviewed: £849.00

    The Rundown

    Sound Quality


    Build Quality


    Value For Money




    Our Review Ethos

    Read about our review ethos and the meaning of our review badges.

    To comment on what you've read here, click the Discussion tab and post a reply.

    Write your REL T/7i Subwoofer review.