In this review, we will be comparing Thetis 300 and KUBE 8b, two Powered Subwoofer speakers from Triangle 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 Triangle Thetis 300 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.Triangle Thetis 300and KEF KUBE 8b have the same driver set up: Both subwoofers have 1 x 8" drivers.
Frequency Response
Thetis 300 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 Thetis 300 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
Cabinet Type
The Triangle Thetis 300 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.
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 Triangle Thetis 300's and KEF KUBE 8b's external dimensions. Triangle Thetis 300 has external dimensions of 340.0 x 300.0 x 300.0mm (13-3/8 x 11-13/16 x 11-13/16inch) 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 4mm narrower and 46mm shorter than Triangle Thetis 300 but it is also 39mm deeper.
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.
KEF KUBE 8b needs about 11% more floor or shelf area. KEF KUBE 8b is 39mm deeper, so it stands that much further out from the wall. Triangle Thetis 300 is 46mm 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 Triangle Thetis 300 is approximately 900.0cm2 / 139.5inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The Thetis 300 requires 10% less surface area than the KUBE 8b which gives it a small advantage 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 Triangle Thetis 300 weighs 10.60kg / 23.3lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the KUBE 8b 7% heavier than the Thetis 300.
Here is a comparison of how Thetis 300 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 |
 Base Surface Area |
900cm2
vs
1003cm2
|
Takes less floor space |
 High Frequency Response |
140 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
294mm
vs
340mm
|
Easier to fit in smaller spaces |
 Price per pair* |
600USD
vs
650USD
|
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.
KEF KUBE 8b needs about 11% more floor area. KEF KUBE 8b stands 39mm further into the room. Triangle Thetis 300 is 46mm taller.
| General |
Triangle Thetis 300 |
KEF KUBE 8b |
| Brand |
Triangle |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
150 watts |
300 watts |
| Frequency Response |
32-120 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
150-watt RMS |
300-watt RMS |
| Watts Peak (Max) |
250-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
8" |
| Woofer Composition |
Paper composite |
|
| 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 |
340.0mm (13.4") |
294.0mm (11.6") |
| Width |
300.0mm (11.8") |
296.0mm (11.7") |
| Depth |
300.0mm (11.8") |
339.0mm (13.3") |
| Weight |
10.60kg (23.3lbs) |
11.36kg (25lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
5 Years |
2 Years |
| Labor Warranty |
5 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 | evenly matched | Effectively the same reach (32Hz vs 34Hz). |
| Amplifier power | B | KEF KUBE 8b has the bigger amplifier - 300W against 150W RMS, about 3dB 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 | depends | Triangle Thetis 300 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. |
| Speaker-level inputs | A | Triangle Thetis 300 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. |
| Driver placement | depends | Triangle Thetis 300 fires down and KEF KUBE 8b fires front. A down-firing driver is more forgiving of a grille-less look and of a hard floor; a front-firing one is the safer choice on a thick carpet or a suspended timber floor. |
| Warranty | A | Triangle Thetis 300 carries 5 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 $650, about 8% less. |
A Triangle Thetis 300 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: Triangle Thetis 300 measures better, KEF KUBE 8b costs about 8% 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, Triangle Thetis 300 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. Check your amplifier first: if it has no subwoofer or preamp output, Triangle Thetis 300 is the only one of these two you can connect at all.
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.