In this review, we will be comparing Elite ES8 and KUBE 10b, 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 ES8 and KEF KUBE 10b 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 ES8and KEF KUBE 10b have a single woofer setup however the Polk Signature Elite ES8's woofer is 8-inch whereas the KEF KUBE 10b features a 10-inch woofer.
Frequency Response
Elite ES8 has a frequency range of 32-180 Hz whereas KUBE 10b has a frequency range of 24-140 Hz. With a minimum frequency of 24Hz, the KUBE 10b can go significantly deeper on the low side and provide stronger bass compared to the Elite ES8's min frequency of 32Hz.
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 Polk Signature Elite ES8 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 10b 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 ES8 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 ES8's and KEF KUBE 10b's external dimensions. Polk Signature Elite ES8 has external dimensions of 385.0 x 326.0 x 437.0mm (15-1/8inch x 12-13/16inch x 17-3/16inch) whereas KEF KUBE 10b has external dimensions of 372.0 x 356.0 x 397.0mm (14-5/8 x 14 x 15-5/8inch).
KEF KUBE 10b is 13mm shorter and 40mm less deeper than Polk Signature Elite ES8 but it is also 30mm wider.
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.
Near-identical footprints. Polk Signature Elite ES8 is 40mm deeper, so it stands that much further out from the wall. Polk Signature Elite ES8 is 13mm 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 ES8 is approximately 1424.6cm2 / 220.8inch2 and base area of the KEF KUBE 10b is approximately 1413.3cm2 / 219.1inch2. The Elite ES8 requires 1% more surface area than the KUBE 10b 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 ES8 weighs 17.73kg / 39lbs and the KEF KUBE 10b weighs 17.50kg / 38.5lbs. This makes the Elite ES8 1% heavier than the KUBE 10b.
Here is a comparison of how Elite ES8 and KUBE 10b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of Polk Signature Elite ES8?
Here are the items that are included inside the box of Elite ES8:
- Powered subwoofer
- Grille
- 6-feet AC power cord
- Owners Manual
- Online Product Registration sheet
What's in the Box of KEF KUBE 10b?
Here are the items that come with the KUBE 10b:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 High Frequency Response |
180 Hz
vs
140 Hz
|
Generates higher frequency |
 Price per pair* |
449USD
vs
750USD
|
costs less (*prices may change depending on the seller, location and time) |
 Woofer Size |
10 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
24 Hz
vs
32 Hz
|
Generates deeper bass |
 Height |
372mm
vs
385mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1413cm2
vs
1424cm2
|
Takes less floor space |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
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. Polk Signature Elite ES8 stands 40mm further into the room. Polk Signature Elite ES8 is 13mm taller.
| General |
Polk Signature Elite ES8 |
KEF KUBE 10b |
| Brand |
Polk Audio |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
100 watts |
300 watts |
| Frequency Response |
32-180 Hz |
24-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
100-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
10" |
| 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 |
385.0mm (15.2") |
372.0mm (14.6") |
| Width |
326.0mm (12.8") |
356.0mm (14") |
| Depth |
437.0mm (17.2") |
397.0mm (15.6") |
| Weight |
17.73kg (39lbs) |
17.50kg (38.5lbs) |
| 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 | B | KEF KUBE 10b goes deeper - 24Hz against 32Hz. That gap covers the lowest notes of a five-string bass and a concert bass drum. |
| Amplifier power | B | KEF KUBE 10b has the bigger amplifier - 300W against 100W RMS, about 4.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | KEF KUBE 10b moves more air: 10" against 8" is 1.56x the cone area, not the 1.25x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | Polk Signature Elite ES8 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 10b 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. |
| Wireless option | depends | Only KEF KUBE 10b 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. |
| Warranty | A | Polk Signature Elite ES8 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 | A | Polk Signature Elite ES8 costs less - $449 against $750, about 40% less. |
A Polk Signature Elite ES8 B KEF KUBE 10b
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: KEF KUBE 10b measures better, Polk Signature Elite ES8 costs about 40% 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 ES8 will hit harder for the money; if it is mainly for music in a normal-sized room, KEF KUBE 10b is usually the easier one to make sound right. 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 $449 each, two Polk Signature Elite ES8 cost about $898 against $750 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.