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JBL Stage A120P

Powered subwoofer

Item # 109SA120P

When I added a sub to my home theater, it was like a missing puzzle piece fell into place.

When I added a sub to my home theater, it was like a missing puzzle piece fell into place.

California customers:
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Item # 109SA120P

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$499.95 -$200.00 Special purchase


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Since 1974

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About the JBL Stage A120P

Add impact to movies and music 

When I added a sub to my home theater, it was like a missing puzzle piece fell into place. And I didn't just hear the difference, I felt it. The JBL Stage A120P delivers that crucial low-end rumble with a powerful 250-watt amplifier and a 12" woofer made out of stiff polycellulose for deep bass. The cabinet is built to be as rigid and resonance-free as possible, with two tuned rear ports for enhanced low-frequency output.

Add impact to movies and music 

When I added a sub to my home theater, it was like a missing puzzle piece fell into place. And I didn't just hear the difference, I felt it. The JBL Stage A120P delivers that crucial low-end rumble with a powerful 250-watt amplifier and a 12" woofer made out of stiff polycellulose for deep bass. The cabinet is built to be as rigid and resonance-free as possible, with two tuned rear ports for enhanced low-frequency output.

Get the most out of your sub

Where you place your sub within your room makes a big difference in how it sounds. Check out our tips for placement and setup to get the best performance out of your system.

Build a complete JBL Stage system

Combine the A120P with other JBL Stage speakers for a complete home theater system.

Bookshelf speakers: A120 or A130
Floor-standing speakers: A170, A180, or A190
Center channel speakers: A125C or A135C


Product highlights:

  • frequency response: 32-150 Hz
  • 250-watt RMS amplifier (500 watts peak power)
  • 12" polycellulose woofer
  • bass-reflex design with rear-firing tuned ports
  • rear-mounted volume, crossover, phase, and power controls
    • continuously variable low-pass 50-150 Hz crossover
    • phase switch to acoustically match the subwoofer's output to your main speakers
    • main power on/off switch plus auto standby/on mode
  • line-level/LFE input
  • detachable power cord
  • removable grille
  • 15-7/16"W x 16-5/16"H x 18-11/16"D
  • weight: 41.09 lbs.
  • warranty: 5 years woofer, 1 year amplifier
  • Our 60-day money-back guarantee

What's in the box:

  • Powered subwoofer
  • Grille
  • 6' AC power cord
  • 4 Spike feet
  • Owner's Manual
  • Warranty Card
  • Important Safety Instructions

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More details on the JBL Stage A120P

Stacey B.

Features & specs

Enclosure Ported
Video Shielded No
Woofer Size (inches) 12
Woofer Composition Polycellulose
Firing Direction Front
Wireless No
Preamp-Level Inputs Mono-RCA/LFE
Speaker-Level Inputs No
Speaker-Level Outputs No
Low-Pass Crossover Freq 50-150Hz
High-Pass Crossover Freq N/A
Phase Switch Yes
Amplifier Output (watts) 250
Frequency Response 32-150 Hz
Height (inches) 16-5/16
Width (inches) 15-7/16
Depth (inches) 18-11/16
Weight 41.09 lbs
Speaker Parts Warranty 5 Years
Speaker Labor Warranty 5 Years
Amplifier Parts Warranty 1 Year
Amplifier Labor Warranty 1 Year

Product Research


12" Woofer: The JBL Stage Sub 120P features a front-firing 12" high-output polycellulose woofer with rubber surround for powerful low-frequency performance that makes your movie & music soundtracks come alive. 

250 Watt Amp: The 12" woofer is powered by a built-in 250-watt (RMS)/500-watt (Peak) amplifier for dynamic and accurate bass performance.

Bass Reflex Cabinet: The 10" woofer is housed in a bass reflex cabinet with dual rear-firing ports which optimize airflow, while minimizing port turbulence and audible distortion in the bass response. The cabinet features MDF construction and is covered in a black vinyl. It also includes a detachable cloth grille.

Controls: The JBL Stage Sub 120P offers Volume, Crossover, and Phase controls to fine-tune the powered subwoofer to your speaker system and room.

  • Volume: Use this control to adjust the powered subwoofer's volume in relation to the volume level of the rest of your speaker system. Once you have balanced the subwoofer's volume with that of the other speakers in your system, you shouldn't have to change the volume control setting.
  • Crossover: The variable 24dB/octave Crossover adjusts the subwoofer's built-in low-pass filter crossover between 50Hz and 150Hz. The higher you set the variable Crossover, the higher in frequency the subwoofer will operate and the more its bass will "overlap" that of the speakers. This adjustment helps achieve a smooth transition of bass frequencies between the subwoofer and the speakers for a variety of different rooms and subwoofer locations
  • Phase: The Phase switch (Normal or Reverse) determines whether the woofer's piston-like action moves in-and-out in phase with the main speakers. If the subwoofer were to play out of phase with the main speakers, the sound waves from the main speakers could partially cancel out the sound waves from the subwoofer, reducing bass performance and sonic impact. This phenomenon depends in part on the placement of all the speakers relative to the listening position and to each other in the room.

LFE/RCA Input: The JBL Stage Sub 120P is fitted with a mono-RCA/LFE input for connecting your home theater or stereo receiver. If your receiver is equipped with a dedicated LFE output, make sure to turn the powered sub's variable crossover fully clockwise to bypass the subwoofer's internal crossover in order to use your receiver's built-in crossover; you will need a mono-subwoofer cable (sold separately). If your receiver is not equipped with dedicated LFE output, but does offer a stereo pre-out, you will need a RCA Y-adapter in addition to a mono-subwoofer cable (both sold separately); in this case you will use the powered sub's built-in variable crossover, which can be set between 50Hz and 150Hz.

Power Modes: In "Auto" mode, the powered sub will automatically turn on when an audio signal is detected and will return to the standby mode when no audio signal is detected after approximately 10 minutes. Setting the Power switch to "On" keeps the subwoofer powered until the Power switch is turned "Off". The subwoofer's LED will glow blue when the subwoofer is on and will glow red when the subwoofer is in standby.

Rubber or Spike Feet: The JBL powered subwoofer features four integrated rubber feet for use on hardwood, tile, and laminate flooring. Four spike feet are also included for rug and carpet flooring. The spikes screw into the bottom of the rubber feet and add approximately 0.5" to the overall height of the subwoofer. The rubber feet are not removable.

Placement: The performance of a subwoofer is directly related to its placement in the listening room and its physical position relative to the other speakers in the system. While it is true that in general our ears do not hear directional sounds at the low frequencies where subwoofers operate, when installing a subwoofer within the limited confines of a room, the reflections, standing waves and absorptions generated within the room will strongly influence the performance of any subwoofer system. As a result, the specific location of the subwoofer in the room does become important to the amount and quality of bass that is produced.

  • Placing the subwoofer next to a wall generally will increase the amount of bass in the room; placing it in a corner generally will maximize amount of bass in the room. However, corner placement can also increase the destructive effect of standing waves on bass performance. This effect can vary depending on the listening position - some listening positions may yield very good results while others may have far too much (or too little) bass at certain frequencies.
  • In many rooms, placing the subwoofer along the same plane as the left and right speakers can produce the best integration between the sound of the subwoofer and that of the left and right speakers. In some rooms, the best performance could even result from placing the subwoofer behind the listening position.
  • It is strongly recommend that you experiment with placement before choosing a final location for your subwoofer. One way you can determine the best location for the subwoofer is by temporarily placing it in the listening position and playing music with strong bass content.

Stage Series: The JBL Stage series delivers JBL signature sound for music and movie soundtracks. The Stage series consists of three floorstanding loudspeakers (A170/A180/A190), two bookshelf loudspeakers (A120/A130), two center channel loudspeakers (A125C/A135C) , and two powered subwoofers (A100P/A120P).

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Customer Q&A

3 questions already asked

Where its made?
[ Luiz  Aug 04, 2022 ]
1 answer
The JBL Stage A120P is made in China.
[ Allison  Aug 05, 2022 ]  Staff
Is there any demos of the sub anywhere?
[ Jordan  Nov 04, 2021 ]
2 answers
I'm not familiar with any pop outlets selling this particular sub. I bought it because I've had great experience with JBL products and I'm very satisfied on all aspects of it.
[ Matthew  Nov 04, 2021 ]
No I went by reviews.
[ Michael  Nov 04, 2021 ]
What class of amplifier is used in the JBL a120p?
[ Scoot dooter  Dec 27, 2020 ]
1 answer
Hola! I use Class A amplifier for my main speakers (JBL Stage a190), and a Class A/B amplifier at 1000 Watts for the a120p subwoofer if unpowered. And, I have been very pleased with the included 'powered subwoofer' as is with just a shielded line-level output to the subwoofer's input. (BTW, I am really pleased with this subwoofer.) I use the device for home audio in the dining room mainly for playing old 78 records after dinner, and another one in the kitchen for television. 73 de Rick/Pittsburgh
[ Richard  Dec 27, 2020 ]

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