In this review, we will be comparing R-121SW and KUBE 8b, two Powered Subwoofer speakers from Klipsch 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 Klipsch R-121SW 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 Klipsch R-121SWand KEF KUBE 8b have a single woofer setup however the Klipsch R-121SW's woofer is 12-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
R-121SW has a frequency range of 28-120 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 28Hz, the R-121SW 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 Klipsch R-121SW has a Bass Reflex type cabinet. Bass Reflex type subwoofers (aka Ported, Vented or Reflex Port) have enclosures that uses a port, hole or vent cut into the cabinet. Ported designs are generally more efficient than the Sealed designs. 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.
Klipsch R-121SW Port
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 Klipsch R-121SW's and KEF KUBE 8b's external dimensions. Klipsch R-121SW has external dimensions of 423.0 x 407.0 x 532.0mm (16-5/8inch x 16inch x 20-15/16inch) 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).
Klipsch R-121SW is clearly the larger of the two speakers. Its body is 111mm wider, 129mm taller and 193mm deeper than KEF KUBE 8b.
Below you can see the front view size comparison of Klipsch R-121SW and KEF KUBE 8b in scale.
Comparison image of Klipsch R-121SW and KEF KUBE 8b Size and External Dimensions
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 Klipsch R-121SW is approximately 2165.2cm2 / 335.6inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The R-121SW requires 116% 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 Klipsch R-121SW weighs 16.00kg / 35.2lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the R-121SW 41% heavier than the KUBE 8b.
Here is a comparison of how R-121SW 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 Klipsch R-121SW?
Here are the items that are included inside the box of R-121SW:
- Powered subwoofer
- Grille
- 6.5-feet AC power cord
- User Manual
- Important Safety Instructions
- Warranty Information
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 |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
28 Hz
vs
34 Hz
|
Generates deeper bass |
 Price per pair* |
599USD
vs
600USD
|
costs less (*prices may change depending on the seller, location and time) |
 High Frequency Response |
140 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
294mm
vs
423mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
2165cm2
|
Takes less floor space |
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.
Klipsch R-121SW needs about 116% more floor area. Klipsch R-121SW stands 193mm further into the room. Klipsch R-121SW is 129mm taller.
| General |
Klipsch Reference R-121SW |
KEF KUBE 8b |
| Brand |
Klipsch |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
200 watts |
300 watts |
| Frequency Response |
28-120 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
200-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
8" |
| Woofer Composition |
Spun-Copper TCP |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
423.0mm (16.7") |
294.0mm (11.6") |
| Width |
407.0mm (16") |
296.0mm (11.7") |
| Depth |
532.0mm (20.9") |
339.0mm (13.3") |
| Weight |
16.00kg (35.2lbs) |
11.36kg (25lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
2 Years |
| Labor Warranty |
2 Years |
2 Years |
A ported subwoofer against a sealed one. That is the most consequential line on this page: it decides how the bass rolls off, how it behaves in a small room, and how much output you get for the size of the box.
| Area | Better | Why |
|---|
| Bass depth | A | Klipsch R-121SW goes deeper - 28Hz against 34Hz. A real difference, though most music has little content below 34Hz. |
| Amplifier power | B | KEF KUBE 8b has the bigger amplifier - 300W against 200W RMS, about 1.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | Klipsch R-121SW moves more air: 12" against 8" is 2.25x the cone area, not the 1.5x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | Klipsch R-121SW is ported - a ported box gives more output low down for its size, at the cost of a steeper roll-off below tuning; KEF KUBE 8b is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Cabinet size | depends | KEF KUBE 8b is about 68% 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 | evenly matched | Priced within a few per cent of each other. |
A Klipsch R-121SW 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?
Klipsch R-121SW has the edge on paper, though not by much. The "depends" rows are more likely to decide this than the score is. Films or music? If this is mainly a home cinema, Klipsch R-121SW will hit harder for the money; if it is mainly for music in a normal-sized room, KEF KUBE 8b is usually the easier one to make sound right. If placement is the constraint - a corner, behind a sofa, under a desk - KEF KUBE 8b is the one that will actually go there, and a well-placed small subwoofer beats a badly-placed big one every time.
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.