In this review, we will be comparing XT15 and A120, two Passive Bookshelf speakers from Polk Audio and JBL.
Let's have a brief look at the main features
of Polk XT15 and JBL A120 first before getting into our more
detailed comparison.
| Key Specs | Polk XT15 | JBL A120 |
|---|
| Brand | Polk Audio
United States · founded 1972 | JBL
United States · founded 1946 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Soft-Dome | 1" Hard-Dome |
|---|
| Woofer | 5.25" Bi-laminate paper | 4.5" Polycellulose |
|---|
| Frequency response | 48-40k Hz | 60-40k Hz |
|---|
| Sensitivity | 86 dB | 86 dB |
|---|
| Impedance | 8 ohms | 6 ohms |
|---|
| Power range | 30-150 watts | 20-125 watts |
|---|
| Weight | 4.09kg / 9lbs | 3.82kg / 8.4lbs |
|---|
| Dimensions (H x W x D) | 10-5/8" x 6-9/16" x 7-3/16"
270.0 x 167.0 x 183.0mm | 11-1/4" x 6-3/4" x 7-7/16"
286.0 x 172.0 x 189.0mm |
|---|
What size room are the Polk XT15 and JBL A120 speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision
factor. Here we have compared their suitability to various sizes of environments considering their size
and max power parameters:
| Listening Environment* |
Polk XT15 |
JBL A120 |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Average |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Average |
| Very Large Room |
Poor |
Poor |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2,
Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: >
400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual
listening experience changes depending on floor height, room shape, surface materials, listening
position, speaker locations, etc.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both XT15 and A120 are 2-way speakers.
Polk XT15JBL A120
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Polk XT15 |
JBL A120 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 4.5-inch
|
XT15 features a 1" Soft-Dome Tweeter and 1 x 5.25" Bi-laminate paper Woofer. On the other hand, the A120 features a 1" aluminum Hard-Dome Tweeter and 1 x 4.5" Polycellulose Woofer.
Frequency Response
XT15 has a frequency range of 48-40k Hz whereas A120 has a frequency range of 60-40k Hz. With a minimum frequency of 48Hz, the XT15 can go significantly deeper on the low side and provide stronger bass compared to the A120's min frequency of 60Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
XT15 is a 8 ohms speaker compared to the A120 which has a nominal impedance of 6 ohms.
On the other hand, they have the same sensitivity of 86 dBdB.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
XT15 can handle a max power of 150 watts RMS, whereas A120 has a max power handling value of 125 watts RMS, 25 watts less than the XT15.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier - change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
XT15 features 5-way post type posts and A120 has a 5-way post type posts. None of these speakers feature bi-amping/bi-wiring.
JBL A120's 5-way post terminals
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 XT15's and JBL A120's external dimensions. Polk XT15 has external dimensions of 270.0 x 167.0 x 183.0mm (10-5/8 x 6-9/16 x 7-3/16inch) whereas JBL A120 has external dimensions of 286.0 x 172.0 x 189.0mm (11-1/4 x 6-3/4 x 7-7/16inch).
JBL A120 is clearly the larger of the two speakers. Its body is 5mm wider, 16mm taller and 6mm deeper than Polk XT15.
Below you can see the front view size comparison of Polk XT15 and JBL A120 in scale.
Comparison image of Polk XT15 and JBL A120 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 Polk XT15 is approximately 305.6cm2 / 47.4inch2 and base area of the JBL A120 is approximately 325.1cm2 / 50.4inch2. The XT15 requires 6% less surface area than the A120 which gives it a small advantage on placement in tight spaces.
Here is another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of Polk XT15 and JBL A120 on a Media Console
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Polk XT15 weighs 4.09kg / 9lbs and the JBL A120 weighs 3.82kg / 8.4lbs. This makes the XT15 7% heavier than the A120.
Here is a comparison of how XT15 and A120's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Polk XT15?
Here are the items that are included inside the box of XT15:
- 2 Bookshelf loudspeakers
- 2 Grilles (attached)
- 8 Self-adhesive rubber feet
- Owners Manual
- Online Product Registration
What's in the Box of JBL A120?
Here are the items that come with the A120:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 2 Foam plugs
- 4 Brackets
- 8 Rubber feet
- 8 Screws (M6 x 8mm)
- Owner-feets Manual
- Warranty Card
 Max Input Power |
150 watts
vs
125 watts
|
Handle more power from your amplifier |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
 Woofer Size |
5.25 inches
vs
4.5 inches
|
Larger woofer |
|
Low Frequency Response |
48 Hz
vs
60 Hz
|
Generates deeper bass |
 Height |
270mm
vs
286mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
305cm2
vs
325cm2
|
Takes less floor space |
 Price per pair* |
199USD
vs
250USD
|
costs less (*prices may change depending on the seller, location and time) |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
| General |
Polk Audio Monitor XT15 |
JBL Stage A120 |
| Brand |
Polk Audio |
JBL |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
30-150 watts |
20-125 watts |
| Sensitivity |
86 dB |
86 dB |
| Impedance |
8 ohms |
6 ohms |
| Frequency Response |
48-40k Hz |
60-40k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
4.5" |
| Woofer Composition |
Bi-laminate paper |
Polycellulose |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Soft-Dome |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
270.0mm (10.6") |
286.0mm (11.3") |
| Width |
167.0mm (6.6") |
172.0mm (6.8") |
| Depth |
183.0mm (7.2") |
189.0mm (7.4") |
| Weight |
4.09kg (9lbs) |
3.82kg (8.4lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF, Vinyl |
MDF, Vinyl |
| Available Colors |
Black |
Black |
| Mounting Bracket |
No |
Keyholes w/ bracket |
| Recommended Stand Height |
28-32" |
26-28" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass | A | Polk XT15 digs deeper - 48Hz against 60Hz. |
| Amplifier needs | evenly matched | Similar sensitivity (86dB vs 86dB) - both want much the same power. |
| Amplifier match | A | Polk XT15 is the easier load at 8 ohms. |
| Headroom | evenly matched | Similar power handling (150W vs 125W). |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Price | A | Polk XT15 is cheaper - $199 against $250, about 20% less. |
A Polk XT15 B JBL A120
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 speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Polk XT15 is the easier recommendation: it leads on most of the measured areas and costs less. Take JBL A120 if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 60Hz anyway, so judge these on the other rows instead.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.