In this review, we will be comparing Elite ES12 and KUBE 8b, two Powered Subwoofer speakers from Polk Audio 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 Polk Signature Elite ES12 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 Polk Signature Elite ES12and KEF KUBE 8b have a single woofer setup however the Polk Signature Elite ES12's woofer is 12-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
Elite ES12 has a frequency range of 22-250 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 22Hz, the Elite ES12 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
Polk Signature Elite ES12
High Frequency
Subwoofer Speakers
Polk Signature Elite ES12
Cabinet Type
The Polk Signature Elite ES12 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.
Polk Signature Elite ES12 double 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 Polk Signature Elite ES12's and KEF KUBE 8b's external dimensions. Polk Signature Elite ES12 has external dimensions of 231.0 x 364.0 x 532.0mm (9-1/16inch x 14-5/16inch 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).
KEF KUBE 8b is 68mm narrower and 193mm less deeper than Polk Signature Elite ES12 but it is also 63mm 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 Polk Signature Elite ES12 is approximately 1936.5cm2 / 300.2inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The Elite ES12 requires 93% 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 Polk Signature Elite ES12 weighs 21.64kg / 47.6lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the Elite ES12 90% heavier than the KUBE 8b.
Here is a comparison of how Elite ES12 and KUBE 8b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
Polk Signature Elite ES12
What's in the Box of Polk Signature Elite ES12?
Here are the items that are included inside the box of Elite ES12:
- Powered subwoofer
- Grille
- 6-feet AC power cord
- Owners Manual
- Online Product Registration sheet
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 |
22 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
250 Hz
vs
140 Hz
|
Generates higher frequency |
 Height |
231mm
vs
294mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
1936cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
849USD
|
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.
Polk Signature Elite ES12 needs about 93% more floor area. Polk Signature Elite ES12 stands 193mm further into the room. KEF KUBE 8b is 63mm taller.
| General |
Polk Signature Elite ES12 |
KEF KUBE 8b |
| Brand |
Polk Audio |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
300 watts |
| Frequency Response |
22-250 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
8" |
| Woofer Composition |
Mineral-filled polypropylene |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
231.0mm (9.1") |
294.0mm (11.6") |
| Width |
364.0mm (14.3") |
296.0mm (11.7") |
| Depth |
532.0mm (20.9") |
339.0mm (13.3") |
| Weight |
21.64kg (47.6lbs) |
11.36kg (25lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
2 Years |
| Labor Warranty |
3 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 | Polk Signature Elite ES12 goes deeper - 22Hz against 34Hz. That gap covers the lowest notes of a five-string bass and a concert bass drum. |
| Amplifier power | evenly matched | Much the same amplifier (300W vs 300W RMS) - under 1dB apart. |
| Driver area | A | Polk Signature Elite ES12 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 | Polk Signature Elite ES12 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 34% 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. |
| Warranty | A | Polk Signature Elite ES12 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 $849, about 29% less. |
A Polk Signature Elite ES12 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: Polk Signature Elite ES12 measures better, KEF KUBE 8b costs about 29% less. In a normal room, placement will make a bigger difference than the gap between these two. Films or music? If this is mainly a home cinema, Polk Signature Elite ES12 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.