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Rythmik L12 Black Matte finish

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300 Watt 12" Direct Servo Subwoofer

Looking for an affordable truly musical sub that can also used be used for home theater? L12 uses our proprietary servo design to gain low frequency clarity and articulation. For home theater use, L12 has a HT playback mode with rumble filter to limit less audible sub-sonic content. It was our goal to offer the benefits of our advanced Direct Servo technology in a more affordable option, and in doing so - we held nothing back. As a result, you get tight and musical bass you wouldn't normally expect from a subwoofer at this price range. L12 is likely the least expensive servo subwoofer on the market.

arrow Patented Direct Servo technology
arrow 300 watt high current amplifier
arrow Adjustable slope and extension

arrow Free Continental US ground shipping
arrow 300 watt, high current amplifier
arrow 45-day satisfaction guarantee
This budget level sub delivers the same articulate and tuneful bass that our subs are known for and yet provides enough HT bass thanks to its sealed design. The combination of servo and a sealed enclosure is what makes this sub deliver on both quality and quantity in bass. The quickguide for L12 can be found here. This model has a 120-240v switchable power supply. Price includes shipping to 48 US continental states. Shipping to other region or country should inquire with us for actual cost.

What makes this subwoofer unique? It's not that it can plumb the depths with authority. There are already many subwoofers on the market which can do that. The difference is that this subwoofer will reproduce bass with a level of realism that matches what our loudspeakers are known for...

We are most proud to represent these astonishing new subwoofers.

Direct Servo technology, US Patent #6,104,817: What is it?

Direct Servo Diagram

Conventional subwoofers have extremely high distortion. Well regarded conventional subwoofers typically have measured distortion levels exceeding 15% at 20 Hz at 100 dB. This includes many subwoofers costing more than US $3000. We think this is far too high. A well designed servo subwoofer will achieve distortion levels under 3% under the same conditions.

A servo is essential in a subwoofer that aims to be true to the original source material. The benefits are clear:

  • No voice coil thermal-induced compression or distortions.
  • Spider and surround distortion reduced by 6 - 9 dB
  • Flat frequency response that is less dependent on T/S parameters.
  • Audiophile bass sound at an affordable price: articulate, tight, transparent, and well-defined bass

These benefits are all unique to a servo controlled subwoofer, and can't be achieved in a practical and affordable way without a servo.

How it works

Direct Servo uses a very thin sensing coil which is wound adjacent to the voice coil. This coil induces a signal which is fed back into the summing points of the amplifier. This signal is used to correct sources of distortion, and this is achieved without placing any active devices such as transistors or operational amplifiers in the signal path. This simplicity eliminates any secondary or mechanical effects which plagues other technologies.

What are memory effects?

A subwoofer driver contains parts which have a memory effect. This means the driver will not respond perfectly to the signal. The spider and surround both contribute to memory effect in a driver. The voice coil which carries the signal that drives the cone also exhibits a memory effect. This is because the temperature of the voice coil changes with operation, and this changes the resistance. The result is a loss of dynamics. As the driver excursion and power input level increases, both effects get worse in conventional subwoofers. Detail and resolution is lost.

Direct Servo corrects both mechanical and thermal memory effects. The result is much lower distortion, and bass that is true to the original, preserving the subtle details, capturing dynamics and revealing a level of detail well beyond the reach of most conventional subwoofers.

How is Direct Servo different?

The primary philosophy is to make audio products as simple as they can be. Less is more. These subwoofers put as little into the signal path as possible. This approach applies to the amplifiers, Direct Servo technology and drivers. Most servo subwoofers use an accelerometer, which is another mechanical system with its own limitations. Also extensive protection circuits are required, and these further degrade the signal. As a result, accelerometer based servos are not as accurate as Direct Servo. The superiority of Direct Servo is derived from its simplicity.

Frequency Response:

In the chart below, with bass extension controls set to Low Music, the response is 3 db down at 18Hz. The red and blue lines are the amplitude and phase response, respectively. The phase shift as only 120 degrees. But in reality the microphone itself has 18 degrees of phase shift at 20hz. Therefore L12 only has 102 degrees phase at 20hz.

L12 Response Graph

L12 features bass extension switch allowing users to select among 3 different modes: Low Music (Q=0.5), Low HT (with a 18db/oct rumble filter at 20hz), and High (with 18db/oct bass extension at 28hz). Below is the frequency and phase response of Low HT mode. Note that the phase response (blue line) below 10hz is noisy because the response level is significantly down below 10hz.

L12 Response Graph

The comparison of all 3 modes with LINE-IN is shown below

L12 Response Graph

L12 accepts a pair of LINE-IN and one LFE IN. The LFE input mode extends the upper end response to 200hz.

L12 Response Graph


L12 features a unique bass extension control, shown below. To suit different setups, we also provide a 12 db and 24 db/octave crossover with adjustable range from 30hz to 120hz.

L12 Controls The bass extension control enables the user to customize the frequency response of the low end for the best trade-off between output and extension. If set to low music, bass below 18 Hz will be filtered. The damping factor of this mode is 0.5 for the best time domain response. However, the disadvantage is slower attenuation of subsonic signals. For HT application, we recommend low-HT mode which incorporates a 3rd order highpass filter to filter out subsonic signals below 20hz. High extension setting is recommended for application where longer playback time and lower power consumption is required.

RCA Inputs:

L12 Controls

120V- 240 User Switchable Voltage Selection:

Correct voltage must be selected before use. Voltage switch is shown below.

L12 Controls


These are some of the finest subwoofers ever manufactured and the difference in sound quality between these subwoofers and the typical big-box ported subwoofer is surprising. You will hear the difference the very first time you listen and as so many have said, you will never go back to a non-servo subwoofer...

Specifications L12:

Frequency Response LFE In 18 Hz - 200 Hz (+/- 3dB)
Frequency Response Line In 18 Hz - 100 Hz (+/- 3dB)
Woofer 12" high excursion with custom sensing coil
Woofer Material paper cone with lightweight rubber surround copper flux de-modulation shorting rings
Amplifier 300w RMS Hypex class D servo controlled
Dimensions W x H x D 14" x 14" x 15-1/2" with grille and amplifier knobs
Shipping Weight 58 lbs
Crossover Slope Selectable 12 or 24 dB / octave
Crossover Range (Low Pass) Continuously variable 30 - 120 Hz
Rumble Filter (High Pass) 20 Hz 18 dB / octave
Phase Adjustment 0 - 180 degrees continuously variable
Bass Extension Settings Low music (Q=0.5), Low-HT(Q=0.9), and high (Q=0.8)
Standby Power 7W (standby, red light), 13W(ON,green light)
Finish Black Oak, Black Matte
Warranty 5 years on woofer / 3 years on electronics
45-day satisfaction guarantee