In this review, we will be comparing No.36 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 No.36 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.Both REL No.36and KEF KUBE 8b have a single woofer setup however the REL No.36's woofer is 15-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
No.36 has a frequency range of 15 Hz (-6dB, in room) whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 15Hz, the No.36 can go significantly deeper on the low side and provide stronger bass compared to 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
Cabinet Type
The REL No.36 has a Sealed type cabinet. On the other hand the KEF KUBE 8b have Acoustic Suspension type enclosure. Acoustic Suspension aka Sealed type subwoofers have enclosures that are sealed hence no ports or holes exists on the cabinet. Sealed designs helps to provide more accurate and tight bass responses compared to ported designs.
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 No.36's and KEF KUBE 8b's external dimensions. REL No.36 has external dimensions of 541.0 x 743.0 x 816.0mm (21-5/16 x 29-1/4 x 32-1/8inch) 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 No.36 is clearly the larger of the two speakers. Its body is 447mm wider, 247mm taller and 477mm deeper than KEF KUBE 8b.
Size, drawn to scale
Both speakers 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 surface and pushed back to the same wall, so the deeper one visibly sticks out further.
REL No.36 needs about 504% more floor or shelf area. REL No.36 is 477mm deeper, so it stands that much further out from the wall. REL No.36 is 247mm taller.
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 No.36 is approximately 6062.9cm2 / 939.7inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The No.36 requires 504% 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 No.36 weighs 91.80kg / 202lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the No.36 708% heavier than the KUBE 8b.
Here is a comparison of how No.36 and KUBE 8b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of REL No.36?
Here are the items that are included inside the box of No.36:
- Subwoofer
- Grille
- 6 ft AC power cord
- 32 ft Neutrik Speakon cable
- User manual and warranty information
- Reference remote
- 2 AAA batteries
- Line Array mounting hardware
What's in the Box of KEF KUBE 8b?
Here are the items that come with the KUBE 8b:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 Woofer Size |
15 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
15 Hz
vs
34 Hz
|
Generates deeper bass |
 Handheld Remote |
Yes
vs
No
|
Control the speaker by the included RC |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
 High Frequency Response |
140 Hz
vs
Hz
|
Generates higher frequency |
 Height |
294mm
vs
541mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
6062cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
12000USD
|
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.
REL No.36 needs about 504% more floor area. REL No.36 stands 477mm further into the room. REL No.36 is 247mm taller.
| General |
REL No.36 |
KEF KUBE 8b |
| Brand |
REL |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
300 watts |
| Frequency Response |
15 Hz (-6dB, in room) |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
15" |
8" |
| Woofer Composition |
Carbon fibre |
|
| 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 |
541.0mm (21.3") |
294.0mm (11.6") |
| Width |
743.0mm (29.3") |
296.0mm (11.7") |
| Depth |
816.0mm (32.1") |
339.0mm (13.3") |
| Weight |
91.80kg (202lbs) |
11.36kg (25lbs) |
| Enclosure |
Sealed |
Acoustic Suspension |
| Finish |
Piano Black Lacquer, 12 coats |
n/a |
| Available Colors |
Black |
n/a |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
2 Years |
| Labor Warranty |
|
2 Years |
Two quite different sizes of subwoofer. Room volume decides this more than anything else on the page: a big driver in a small room is wasted, and a small one in a large room is worked to death.
| Area | Better | Why |
|---|
| Bass depth | A | REL No.36 goes deeper - 15Hz against 34Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | A | REL No.36 has the bigger amplifier - 1000W against 300W RMS, about 5.2dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | REL No.36 moves more air: 15" against 8" is 3.52x the cone area, not the 1.88x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Speaker-level inputs | A | REL No.36 takes a speaker-level connection as well as line level. That is what lets it work with an integrated amplifier or a vintage receiver that has no subwoofer output at all. |
| Wireless option | depends | Only REL No.36 offers a wireless link (as a paid option). It decides where the sub can go if you cannot run a cable, and is worth nothing if you can. |
| Cabinet size | depends | KEF KUBE 8b is about 91% smaller by volume. In a subwoofer that is a real trade rather than a preference: box volume is how you get output low down without a bigger amplifier. |
| Price | B | KEF KUBE 8b costs less - $600 against $12,000, about 95% less. |
A REL No.36 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?
The usual trade-off: REL No.36 measures better, KEF KUBE 8b costs about 95% less. In a normal room, placement will make a bigger difference than the gap between these two. Check your amplifier first: if it has no subwoofer or preamp output, REL No.36 is the only one of these two you can connect at all. Two small subwoofers beat one big one in most rooms - a pair evens out the room modes in a way no single box can, whatever its specs. At $600 each, two KEF KUBE 8b cost about $1,200 against $12,000 for one of the other, which is worth a thought.
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.