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Ultra-compact subwoofer delivers big bass

Definitive's smallest subwoofer, the SuperCube III provides huge bass performance in a compact, room-friendly enclosure that takes up less than a cubic foot of floor-space. The secret to its success is an active woofer/passive radiator combination that produces big sound despite the cabinet's small size. And a powerful built-in 650-watt amplifier really shows off this little sub's tight, accurate bass response.

Grille off

A unique approach to rock-solid bass


A look at the rear panel offering a number of hookup options.

The SuperCube III contains a 7-1/2" woofer pressure-coupled to two 7-1/2" passive radiators, for a total output around that of a traditional 12" woofer. This driver array gives the SuperCube III the advantage of far greater speed, musicality, and control than any large single-woofer sub could produce. The woofer is encased in an incredibly rigid basket engineered to hold the massive magnet structure and large voice coil in absolute alignment. The non-resonant cabinet is nearly 2" thick and uses multiple internal bracings to make sure that you hear clean bass without sound-muddying vibrations.

Flexible inputs and outputs and advanced controls

Line-level and speaker-level inputs let you connect this sub to just about any audio system. The continuously variable low-pass crossover allows you to precisely control the frequencies that your subwoofer handles. And the built-in high-pass crossover is a nice touch: it prevents your main speakers from overloading with low frequencies if you hook them up through the subwoofer's speaker-level outputs.

Product Highlights:

  • bass-reflex (passive radiator) enclosure
  • 7-1/2" long-throw woofer pressure-coupled to two 7-1/2" low bass radiators
  • built-in 650-watt amplifier
  • frequency response 16-200 Hz
  • continuously variable low-pass 40-150 Hz crossover
  • auto on/off
  • phase control dial for fine-tuning bass performance
  • speaker-level inputs and outputs
  • 80 Hz fixed high-pass crossover for speaker-level outputs
  • two pairs of line-level input
  • LFE input for use with home theater receiver's subwoofer output
  • piano-gloss black finish
  • 10-3/16"W x 10-13/16"H x 11-5/16"D
  • warranty: 5 years woofer, 3 years amplifier
  • Our 60-day money-back guarantee

Why add a powered subwoofer?

A powered subwoofer gives you bass you can feel as well as hear. Our customers love the depth and impact their subs add to music and movies. We hear comments like "it brings out sounds I didn't know existed in discs I've watched a million times." Powered subwoofers aren't just for big bass that rattles your picture frames; they can also deliver tight, accurate lows. If you haven't shopped for a powered sub in a while, you might be surprised at how small they get. Look for an ultra-compact model if you want to tuck your sub away under an end table or in a corner.

Definitive Technology SuperCube III Reviews

Average Customer Review:

7 Reviews

Awesome Bass!!!

Written by: Biggjim from Traverse City, MI on October 17, 2011

Crutchfield Customer Review (What's this?)

I must admit I was a little skeptical that this product could deliver especially when I unpacked it and saw how small it really was. After living with it for about a month I am truly amazed at its performance. It puts my old Paradigm 12" sub to shame. Its is probably half the size, but puts out cleaner and more powerful bass than the 12" ever did. I have a relatively small room, 13'x18 and it is more than adequate, it's amazing. Plus it is much more unobtrusive. Thank you Crutchfield!!



Are you kidding me?!

Written by: RickT from Atlanta, GA on September 1, 2011

Crutchfield Customer Review (What's this?)

This sub is just fantastic. I was quite skeptical given the small size, but boy was I impressed when I turned it on. I use the sub for music listening only as it is not hooked up to my home theatre. The base is tight and everyone who hears it is impressed. Highly recommended!




Written by: James from Stonewall, Tx on August 8, 2011

Crutchfield Customer Review (What's this?)

I bought this powered sub to replace one I allready had with a 15" woofer. I was VERY skeptical about something so small, but went with the advice from Harley (crutchfield advisor). I even made sure to keep the box in good condition because I was sure I would have to return it after seeing it was even smaller than I thought it was going to be. Boy was I wrong! I have never heard such deep, clear, undistored bass before from ANY size home speaker. The only down side is to try and keep this speaker in one spot if it is cranked up, I think it might need to be screwed to the floor! Awesome! Thanks Harley and crutchfield.



Definitive Technology SuperCube III

Written by: SPandey from Delaware on May 22, 2011

It is creating the best theater effect in my 28x16 media room.



small cube but big sound

Written by: Angela from Miami,FL on February 18, 2011

Crutchfield Customer Review (What's this?)

I purchased the Definitive Supercube III for my superbowl party a few weeks ago and everyone loved it. I had so many compliments on the sound and the looks of it. Yes,it is small but itdoes not take up a;ot of space and the sound is like at a club. Its truly amazing, i never owned a better subwoofer than this. I highly reccomend to anyone that loves sound and quality as much as I do. I purchased it along with the XTR50 speakers and the sound system is so clear. Thank you crutchfield for such great quality speakers!!



Exceptional for the size and price

Written by: Justink from Cleveland OH on January 10, 2010

I recently purchased this sub with a pair of Studio 20 speakers. This sub was suggested to me over the comparable Paradigm sub. I was truly floored when I heard this little monster. Yes, it can get loud, but more importantly, it's accurate, tight and rich. Music is my main focus. So an accurate, tight sound is very important to me. For the first time, I find myself following discrete bass lines in music I've heard a thousand times. Lows are crystal clear and I have yet to hear a hint of boominess or distortion, even at high volumes. The Supercube III is astonishing for its size.




Written by: Mancari from Las Vegas, NV on August 11, 2009

I have the Supercube III in my master bedroom along with my Yamaha
soundbar and couldn't be happier. Thunderous lows that will amaze you and
your friends especially when you show them how small it is. It is a very clean
bass and never sounds boomy. It may seem kind of pricy for the size but don't
let the looks fool you. This sub will out perform almost anything in this price
range, if not EVERYTHING! Crutchfield should expand their Definitive lineup in
the future and include the Supercube Reference and the monster Supercube
Trinity (which I have in my dedicated theater). Although I am the first reviewer
I'm sure you will see that others will have the same 5 star rating!



Hands-on research

What's in the box?

Download owner's manual

  • 7.5" Powered subwoofer
  • 4 Threaded rubber-feet
  • 4 Spike feet (hex-nut attached)
  • Owner's Manual
  • Online Product Registration card

Features and Specs

Enclosure Passive Radiator
Video Shielded No
Woofer Size (inches) 7 1/2
Woofer Composition
Firing Direction Front
Wireless No
Preamp-Level Inputs Yes
Speaker-Level Inputs Yes
Speaker-Level Outputs Yes
Low-Pass Crossover Freq 40-150 Hz
High-Pass Crossover Freq 80 Hz
Phase Switch Yes
Amplifier Output (watts) 650
Frequency Response 16-200 Hz
Height (inches) 10-13/16
Width (inches) 10-3/16
Depth (inches) 11-5/16
Weight 25 lbs
Speaker Parts Warranty 5 Years
Speaker Labor Warranty 5 Years
Amplifier Parts Warranty 3 Years
Amplifier Labor Warranty 3 Years

Product Research

Overview: The Definitive Technology SuperCube III is a compact, high-quality powered subwoofer intended for use in a music or home theater system. The SuperCube III powered subwoofer allows for easy, seamless integration into almost any two-channel or multichannel speaker system; delivering true, accurate, and extremely deep bass in any room. The SuperCube III is finished in a piano-gloss black lacquer finish with a black non-removable cloth grille.



Passive Radiator Design: The SuperCube III features a 650-watt (RMS) class D amplifier driving a 7-1/2 inch SuperCube Technology woofer pressure coupled to two side-firing 7-1/2 inch Ultra Low Bass Radiators. The total piston area is greater than a 12-inch diameter woofer but with far greater speed, musicality, and control than a single large diameter woofer could deliver.

PowerField Technology Amplifier: The SuperCube III incorporates Definitive's proprietary PowerField technology, by which the amplifier is specifically engineered in conjunction with the driver for optimum load matching and power transfer characteristics. The SuperCube III is powered by a 650-watt (RMS) class D amplifier. The result is high-definition bass performance extending effortlessly down to 16 Hz.

High-Definition Subwoofer: The powerful, high-definition 7-1/2 inch long-throw subwoofer driver is specifically engineered by Definitive Technology to deliver rock-solid low distortion bass, reaching down to the lowest subsonic frequencies (16-200Hz), with superior transient response. The special ultra-stiff, low-mass cone (for super-fast transient response) is joined to a specially formulated surround and long-throw voice coil and spider. The ultra-rigid basket is engineered to hold the woofer's massive magnet structure and large voice coil in absolute alignment. The high temperature voice coil is made of aluminum wound with triple insulated ultra-pure copper wire and baked in epoxy for increased power handling.

Non-Resonant Cabinet: The cabinet of a loudspeaker plays a large part in its sonic performance. Resonance and vibration can add unwanted distortion as well as drain away important energy from the system. The Definitive Technology SuperCube III powered subwoofer utilizes a monocoque cabinet, which has been specifically engineered to be totally inert and vibration free, to ensure you of pure sonic reproduction. Monocoque means that the cabinet is of a unitized construction where all panels are permanently joined together into one solid structure. The cabinet walls themselves are high-density medite fused together by space-age polymer adhesives. The front and rear panels nearly 2-inches thick and the cabinet, itself, incorporates multiple internal braces to ensure total solidity.

Protection Circuits: The Definitive Technology SuperCube III features two protection circuits that ensure that the subwoofer can never be overdriven.

Interchangeable Feet: The SuperCube III comes with 4 rubber feet and 4 spiked feet for safe and secure placement of the powered subwoofer on your carpet or hardwood floors.

Placement: The Definitive Technology powered subwoofer has been designed to operate at frequencies generally below 150 Hz. Because low-frequency information in this range essentially is non-directional, your subwoofer can be located anywhere in your listening room that is most convenient. Also the continuously variable low-pass filter operate at a very fast roll-off, ensuring great performance wherever you place the subwoofer. There are, however, some general rules that you should bear in mind when locating the powered sub.


Subwoofer Controls: A complete array of controls allow the SuperCube III to be perfectly integrated with any stereo or multi-channel audio system, and tuned for optimum performance in any room.

Volume Control: The SuperCube III features a rear-mounted volume control. This control is used to raise or lower the output level of the subwoofer in relation to the other speaker in your system.

Variable Low-Pass Crossover: The Definitive Technology powered subwoofer features a continuous variable low-pass filter control on the back-panel. This filter is continuously variable between 40 and 150 Hz. It "rolls-off" (24dB/oct) the high-frequency response of your subwoofer so only low-frequencies below the desired setting will be heard. This low-pass filter control is used to obtain the optimum transition between the subwoofer and your main speakers.

Variable Phase Alignment: The powered subwoofer features a rear-panel variable phase control dial with a range of 0-180 degrees. This control is used to perfectly blend the output of your subwoofer with your main speakers to compensate for any possible problems due to placement constraints.

Auto Turn-On Circuit: The powered subwoofer has a special power circuit which automatically turns the powered subwoofer on when a signal is fed to the loudspeaker and turns it off when there is no signal present, so it does not require an on-off switch.

LED Indicator: The red LED on the back panel of the powered subwoofer will light up when a signal is sensed and the amplifier turns on. It will automatically turn off with the powered subwoofer, a little while after the signal is discontinued.


Line-Level & Speaker-Level Connections: The Definitive Technology SuperCube III powered subwoofer has a complete range of inputs and outputs to allow easy and effective hookup to any system. Both (high) speaker level and low-level inputs are provided in case you do not have a subwoofer output. In addition, the SuperCube III has a separate direct-in LFE low-level input (which bypasses the crossover network).

Low Level Inputs: This input is an RCA type LFE/Stereo input. If you are connecting your subwoofer to an A/V receiver with an LFE or Subwoofer preamp output, connect a single RCA cable to the LFE input. If you are connecting your subwoofer to an AV receiver without a dedicated subwoofer or LFE preamp output, but does features a stereo RCA output, use a stereo RCA cable for connection.

Speaker Level In: The Speaker Level inputs (binding posts) are designed to be used on receivers or amplifiers that do not incorporate any RCA type subwoofer outputs. If your receiver is equipped with an RCA type subwoofer outputs, these speaker level inputs should not be utilized.

Speaker Level Output: The SuperCube III also features speaker level outputs (binding posts), so you can connect your front (main speakers) through the powered subwoofer. The SuperCube III has a built-in speaker level high-pass crossover preset at 80 Hz (6dB/oct).

  • For maximum output the subwoofer should be placed in a corner or against the wall; leaving roughly 2- to 4-inches of clearance between the subwoofer and the wall(s).
  • Corner placement will increase the subwoofer's efficiency, which in turn will increase your system's maximum output and improve the dynamic capability of the subwoofer.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.