In this review, we will be comparing A120 and R-51M, two Passive Bookshelf speakers from JBL and Klipsch. Let's have a brief look at the main features
of JBL A120 and Klipsch R-51M first before getting into our more
detailed comparison.
What size room are the JBL A120 and Klipsch R-51M 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:
In the following sections, we will get into more detail in order to better understand how the JBL A120 and Klipsch R-51M compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both A120 and R-51M are 2-way speakers.
| Driver |
JBL A120 |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 4.5-inch
|
1 x 5.25-inch
|
A120 features a 1" aluminum Hard-Dome Tweeter and 1 x 4.5" Polycellulose Woofer . On the other hand, the R-51M features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1660Hz.
Frequency Response
A120 has a frequency range of 60-40k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 60Hz, the A120 can go slightly deeper then the R-51M's min frequency of 62Hz.
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 Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
A120 is a 6 ohms speaker compared to the R-51M which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. A120 sensitivity is rated at 86 dB and the R-51M's is rated at 93 dB. This 7 dB difference makes the Klipsch R-51M a more sensitive speaker compared to JBL A120, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. While using an amplifier within this range ensures the nominal performance , inputting a power that is higher than the max wattage can result in a damaged speaker.
A120 can handle a max power of 125 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS, 40 watts less than the A120.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Input Type and Bi-Amping / Bi-Wiring
A120 features Single Gold Plated Binding Posts - 5-way type posts and R-51M has a Single Gold Plated Binding Posts - 5-way type posts. None of these speakers feature bi-amping/bi-wiring.
JBL A120's 5-way post terminals
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
Cabinet Type and Port Position
Both A120 and R-51M have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
Physical Specs
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare JBL A120's and Klipsch R-51M's external dimensions. 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) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) .
Klipsch R-51M is clearly the larger of the two speakers. Its body is 6mm wider, 52mm taller and 26mm deeper than JBL A120.
Below you can see the front view size comparison of JBL A120 and Klipsch R-51M in scale.
Comparison image of JBL A120 and Klipsch R-51M 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 JBL A120 is approximately 325.1cm2 / 50.4inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The A120 requires 15% less surface area than the R-51M which gives it a small advantage on placement in tight spaces.
Here is an 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 JBL A120 and Klipsch R-51M 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 JBL A120 weighs 3.82kg / 8.4lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the R-51M 31% heavier than the A120.
Here is a comparison of how A120 and R-51M's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of JBL A120?
Here are the items that are included inside the box of A120:
2 Bookshelf loudspeakers2 Grilles2 Foam plugs4 Brackets8 Rubber feet8 Screws (M6 x 8mm)Owner-feets ManualWarranty Card
What's in the Box of Klipsch R-51M?
Here are the items that come with the R-51M:
2 Bookshelf loudspeakers 2 Grilles (installed) 8 Self-adhesive rubber feet Quick Setup Guide Important Safety Instructions Warranty Information
 Max Input Power |
125 watts
vs
85 watts
|
Handle more power from your amplifier |
 Low Frequency Response |
60 Hz
vs
62 Hz
|
Generates deeper bass |
 High Frequency Response |
40k Hz
vs
21k Hz
|
Generates higher frequency |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
 Height |
286mm
vs
338mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
325cm2 (172x189mm)
vs
382cm2 (178x215mm)
|
Takes less floor space |
 Price per pair* |
250USD
vs
359USD
|
costs less (*prices may change depending on the seller, location and time) |
 Sensitivity |
93 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
| Woofer Size |
5.25 inches
vs
4.5 inches
|
Larger woofer |
| General |
JBL Stage A120 |
Klipsch Reference R-51M |
| Brand |
JBL |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-125 watts |
Up to 85 watts |
| Sensitivity |
86 dB |
93 dB |
| Impedance |
6 ohms |
8 ohms |
| Frequency Response |
60-40k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
4.5" |
5.25" |
| Woofer Composition |
Polycellulose |
Copper-spun IMG |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Hard-Dome |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
1660Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
286.0mm (11.3") |
338.0mm (13.3") |
| Width |
172.0mm (6.8") |
178.0mm (7") |
| Depth |
189.0mm (7.4") |
215.0mm (8.5") |
| Weight |
3.82kg (8.4lbs) |
5.00kg (11lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF, Vinyl |
MDF/Wood-grain vinyl |
| Available Colors |
Black |
Black |
| Mounting Bracket |
Keyholes w/ bracket |
No |
| Recommended Stand Height |
26-28" |
24-28" |
| 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 |