In this review, we will be comparing Radius 390 and A120P, two Powered Subwoofer speakers from Monitor Audio 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 Monitor Audio Radius 390 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 Monitor Audio Radius 390and JBL Stage A120P have a single woofer setup however the Monitor Audio Radius 390's woofer is 10-inch whereas the JBL Stage A120P features a 12-inch woofer.
Frequency Response
Radius 390 has a frequency range of 30-120 Hz whereas A120P has a frequency range of 32-150 Hz. With a minimum frequency of 30Hz, the Radius 390 can go slightly deeper then the A120P'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 Monitor Audio Radius 390 has a Passive Radiator type cabinet. Passive Radiator type subwoofers sports a non-powered cone that moves in response to the main woofer to move air out in order to generate stronger bass in a smaller body compared to ported or 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 Monitor Audio Radius 390's and JBL Stage A120P's external dimensions. Monitor Audio Radius 390 has external dimensions of 348.0 x 331.0 x 385.0mm (13-11/16 x 13 x 15-1/8inch) 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 62mm wider, 67mm taller and 90mm deeper than Monitor Audio Radius 390.
Below you can see the front view size comparison of Monitor Audio Radius 390 and JBL Stage A120P in scale.
Comparison image of Monitor Audio Radius 390 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 Monitor Audio Radius 390 is approximately 1274.4cm2 / 197.5inch2 and base area of the JBL Stage A120P is approximately 1866.8cm2 / 289.4inch2. The Radius 390 requires 32% 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 Monitor Audio Radius 390 weighs 13.77kg / 30.3lbs and the JBL Stage A120P weighs 18.68kg / 41.1lbs. This makes the A120P 36% heavier than the Radius 390.
Here is a comparison of how Radius 390 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 Monitor Audio Radius 390?
Here are the items that are included inside the box of Radius 390:
- Powered sub
- 6-feet AC power cord
- 10.75-feet Mono minijack cable
- Owners Manual
- Important Safety Instructions
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
 Low Frequency Response |
30 Hz
vs
32 Hz
|
Generates deeper bass |
 Height |
348mm
vs
415mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1274cm2
vs
1866cm2
|
Takes less floor space |
| Woofer Size |
12 inches
vs
10 inches
|
Larger woofer |
 High Frequency Response |
150 Hz
vs
120 Hz
|
Generates higher frequency |
 Price per pair* |
300USD
vs
1150USD
|
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 46% more floor area. JBL Stage A120P stands 90mm further into the room. JBL Stage A120P is 67mm taller.
| General |
Monitor Audio Radius 390 |
JBL Stage A120P |
| Brand |
Monitor Audio |
JBL |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
220 watts |
250 watts |
| Frequency Response |
30-120 Hz |
32-150 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
220-watt RMS |
250-watt RMS |
| Watts Peak (Max) |
n/a |
500-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
10" |
12" |
| Woofer Composition |
C-CAM |
Polycellulose |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
side |
front |
Physical Specs |
|
|
| Height |
348.0mm (13.7") |
415.0mm (16.3") |
| Width |
331.0mm (13") |
393.0mm (15.5") |
| Depth |
385.0mm (15.2") |
475.0mm (18.7") |
| Weight |
13.77kg (30.3lbs) |
18.68kg (41.1lbs) |
| Enclosure |
Passive Radiator |
Bass reflex |
| Grille |
n/a |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
1 Year |
| Labor Warranty |
2 Years |
1 Year |
A passive radiator subwoofer against a ported 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 (30Hz vs 32Hz). |
| Amplifier power | evenly matched | Much the same amplifier (220W vs 250W RMS) - under 1dB apart. |
| Driver area | B | JBL Stage A120P moves more air: 12" against 10" is 1.44x the cone area, not the 1.2x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | Monitor Audio Radius 390 is passive radiator - a passive radiator behaves like a port without the pipe noise, and suits a slim cabinet; JBL Stage A120P is ported - a ported box gives more output low down for its size, at the cost of a steeper roll-off below tuning. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Driver placement | depends | Monitor Audio Radius 390 fires side and JBL Stage A120P 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. |
| Cabinet size | depends | Monitor Audio Radius 390 is about 43% 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 | Monitor Audio Radius 390 carries 2 years on parts against 1 years. A subwoofer amplifier works harder than anything else in the system, so this is not a throwaway line. |
| Price | B | JBL Stage A120P costs less - $300 against $1,150, about 74% less. |
A Monitor Audio Radius 390 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?
Neither runs away with it - they trade advantages. Let your room size and where the box can actually stand settle it. 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 $1,150 for one of the other, which is worth a thought. If placement is the constraint - a corner, behind a sofa, under a desk - Monitor Audio Radius 390 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.