In this review, we will be comparing T 5x and KUBE 8b, two Powered Subwoofer speakers from REL and KEF. Being Powered subwoofers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them. Let's have a brief look at the main features of REL T 5x and KEF KUBE 8b first before getting into our more detailed comparison.
The sections below take each area in turn: driver and amplifier, frequency response, physical size and connectivity.
Drivers
The efficiency of a subwoofer is directly proportional to the total radiating are squared hence the woofer quantity and diameter.REL T 5xand KEF KUBE 8b have the same driver set up: Both subwoofers have 1 x 8" drivers.
Frequency Response
T 5x has a frequency range of 32-120 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 32Hz, the T 5x can go slightly deeper then the KUBE 8b's min frequency of 34Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Subwoofer class in our database.
Low Frequency
Subwoofer Speakers
High Frequency
Subwoofer Speakers
Physical Specs
The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare REL T 5x's and KEF KUBE 8b's external dimensions. REL T 5x has external dimensions of 312.7 x 300.0 x 360.4mm () whereas KEF KUBE 8b has external dimensions of 294.0 x 296.0 x 339.0mm (11-9/16 x 11-5/8 x 13-5/16inch).
REL T 5x is clearly the larger of the two speakers. Its body is 4mm wider, 18.7mm taller and 21.4mm deeper than KEF KUBE 8b.
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the REL T 5x is approximately 1081.2cm2 / 167.6inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The T 5x requires 8% more surface area than the KUBE 8b which gives it a small disadvantage on placement in tight spaces.
Weight Comparison The weight of a subwoofer may become an important factor if you need to move and reposition the unit often to find the optimal positioning, also known as 'Subwoofer Crawling'. The REL T 5x weighs 14.29kg / 31.4lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the T 5x 26% heavier than the KUBE 8b.
Here is a comparison of how T 5x and KUBE 8b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Low Frequency Response |
32 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
140 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
294mm
vs
312mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
1081cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
799USD
|
costs less (*prices may change depending on the seller, location and time) |
Size, drawn to scale
Both subwoofers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same floor and pushed back to the same wall, so the bigger one visibly takes more of the room.
Near-identical footprints. REL T 5x stands 21mm further into the room. REL T 5x is 19mm taller.
| General |
REL T 5x |
KEF KUBE 8b |
| Brand |
REL |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Frequency Response |
32-120 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
125-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
8" |
| Woofer Composition |
|
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
312.7mm (12.3") |
294.0mm (11.6") |
| Width |
300.0mm (11.8") |
296.0mm (11.7") |
| Depth |
360.4mm (14.2") |
339.0mm (13.3") |
| Weight |
14.29kg (31.4lbs) |
11.36kg (25lbs) |
| Enclosure |
|
Acoustic Suspension |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
2 Years |
| Labor Warranty |
3 Years |
2 Years |
No single best subwoofer here. Your room, where the box can physically go, and whether this is mainly for films or mainly for music will settle it long before the specs do.
| Area | Better | Why |
|---|
| Bass depth | evenly matched | Effectively the same reach (32Hz vs 34Hz). |
| Amplifier power | B | KEF KUBE 8b has the bigger amplifier - 300W against 125W RMS, about 3.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (8" against 8"). |
| Enclosure | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Warranty | A | REL T 5x carries 3 years on parts against 2 years. A subwoofer amplifier works harder than anything else in the system, so this is not a throwaway line. |
| Price | B | KEF KUBE 8b costs less - $600 against $799, about 25% less. |
A REL T 5x B KEF KUBE 8b
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both subwoofers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let your room size and where the box can actually stand settle it.
One thing outweighs everything above: where the subwoofer stands. Room modes can add or remove 10dB or more at a given seat, which is far larger than any difference on this page. Before spending more, try the sub in two or three positions - the crawl test, where you put it in the listening seat and crawl the room to find where the bass sounds best, costs nothing and usually beats an upgrade.