In this review, we will be comparing Alpha S8 and A120P, two Powered Subwoofer speakers from PSB and JBL. 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 PSB Alpha S8 and JBL Stage A120P 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 PSB Alpha S8and JBL Stage A120P have a single woofer setup however the PSB Alpha S8's woofer is 8-inch whereas the JBL Stage A120P features a 12-inch woofer.
Frequency Response
Alpha S8 has a frequency range of 35-150 Hz whereas A120P has a frequency range of 32-150 Hz. With a minimum frequency of 32Hz, the A120P can go slightly deeper then the Alpha S8's min frequency of 35Hz.
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 PSB Alpha S8 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 JBL Stage A120P have Bass reflex type enclosure.
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 PSB Alpha S8's and JBL Stage A120P's external dimensions. PSB Alpha S8 has external dimensions of 318.0 x 293.0 x 413.0mm (12-1/2 x 11-1/2 x 16-1/4inch) whereas JBL Stage A120P has external dimensions of 415.0 x 393.0 x 475.0mm (16-5/16 x 15-7/16 x 18-11/16inch).
JBL Stage A120P is clearly the larger of the two speakers. Its body is 100mm wider, 97mm taller and 62mm deeper than PSB Alpha S8.
Below you can see the front view size comparison of PSB Alpha S8 and JBL Stage A120P in scale.
Comparison image of PSB Alpha S8 and JBL Stage A120P 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 PSB Alpha S8 is approximately 1210.1cm2 / 187.6inch2 and base area of the JBL Stage A120P is approximately 1866.8cm2 / 289.4inch2. The Alpha S8 requires 35% less surface area than the A120P 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 PSB Alpha S8 weighs 9.55kg / 21lbs and the JBL Stage A120P weighs 18.68kg / 41.1lbs. This makes the A120P 96% heavier than the Alpha S8.
Here is a comparison of how Alpha S8 and A120P's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of PSB Alpha S8?
Here are the items that are included inside the box of Alpha S8:
- Powered subwoofer
- Grille
- 5-feet AC power cord
- 4 Rubber feet
- 4 Spike feet
- 4 Hex-nuts
- Quick Start Guide
- Important Safety Instructions
- Warranty Information
What's in the Box of JBL Stage A120P?
Here are the items that come with the A120P:
- Powered subwoofer
- Grille
- 6-feet AC power cord
- 4 Spike feet
- Owners Manual
- Warranty Card
- Important Safety Instructions
 Height |
318mm
vs
415mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1210cm2
vs
1866cm2
|
Takes less floor space |
 Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
32 Hz
vs
35 Hz
|
Generates deeper bass |
 Price per pair* |
300USD
vs
549USD
|
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.
JBL Stage A120P needs about 54% more floor area. JBL Stage A120P stands 62mm further into the room. JBL Stage A120P is 97mm taller.
| General |
PSB Alpha S8 |
JBL Stage A120P |
| Brand |
PSB |
JBL |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
150 watts |
250 watts |
| Frequency Response |
35-150 Hz |
32-150 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
150-watt RMS |
250-watt RMS |
| Watts Peak (Max) |
n/a |
500-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
12" |
| Woofer Composition |
Polypropylene |
Polycellulose |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
318.0mm (12.5") |
415.0mm (16.3") |
| Width |
293.0mm (11.5") |
393.0mm (15.5") |
| Depth |
413.0mm (16.3") |
475.0mm (18.7") |
| Weight |
9.55kg (21lbs) |
18.68kg (41.1lbs) |
| Enclosure |
Bass Reflex |
Bass reflex |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
1 Year |
1 Year |
| Labor Warranty |
1 Year |
1 Year |
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 | B | JBL Stage A120P goes deeper - 32Hz against 35Hz. A real difference, though most music has little content below 35Hz. |
| Amplifier power | B | JBL Stage A120P has the bigger amplifier - 250W against 150W RMS, about 2.2dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | JBL Stage A120P 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 | evenly matched | Both are ported designs, so they roll off in much the same way. |
| Cabinet size | depends | PSB Alpha S8 is about 50% 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 | JBL Stage A120P costs less - $300 against $549, about 45% less. |
A PSB Alpha S8 B JBL Stage A120P
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?
JBL Stage A120P is the easier recommendation: it leads on most of the measured areas and costs less. Take PSB Alpha S8 if one of the "depends" rows describes your room. 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 $300 each, two JBL Stage A120P cost about $600 against $549 for one of the other, which is worth a thought. If placement is the constraint - a corner, behind a sofa, under a desk - PSB Alpha S8 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.