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Rythmik LV12F Black Oak finish
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300 Watt 12" Direct Servo Subwoofer

Looking for an affordable home theater sub that is also tight and musical? The LV12F uses a front vented alignment to gain low frequency impact and output that home theater demands. While many of our competitors limit their best technology to their top level models, we wanted to make Direct Servo affordable so we've held nothing back. As a result, you get the tight and musical bass you wouldn't normally expect from a vented subwoofer.

arrow Patented Direct Servo technology
arrow Rear Ported
arrow 300 watt high current amplifier
arrow Adjustable damping and extension
arrow New Version! includes 1 band parametric EQ

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 ported design. The combination of servo and a ported enclosure is what makes this sub deliver on both quality and quantity in bass. The quickguide for LV12F can be found here. This model is only available in 110V-120V.

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:

A quick glance at our frequency response plot will reveal that our LV12F subwoofers have a flat frequency response down to 19hz when bass extension controls are set to low. When used with the LFE input, the phase and cross-over knobs have no function. This is the recommend connection method when used with a modern home theater receiver.

LV12F Response

Fig 1.0 - LV12F Frequency response chart with LFE input, extension switch set to low

Alternatively, one can also use the line inputs with both phase and crossover knobs fully functional. The frequency response is as follows.

LV12F Response

Fig 1.1 - LV12F Frequency response chart with Line input, extension switch set to low


This subwoofer is designed to use with the bass management in an AV receiver. With many subwoofers, it is difficult to get a correct and seamless integration with the main speakers because the amplifier settings are often very different to the measured response. You may set the crossover point to 80 Hz, but the actual crossover point may be anywhere between 60 and 100 Hz! The crossover control knob on our plate amplifier can serve as a fine tuning tool to reduce the overlap in output between the main speakers and the subwoofer. The sub has 3 extension settings for 3 different frequency response contours. Low extension setting also employs low damping to give a more full-body bass sound. High extension setting, on the other hand, employs high damping to give a more articulate bass sound.

LV12F Response

Fig 1.1 - LV12F Frequency response chart with 3 different extension settings

Extension filter settings to match your room

Vented subwoofers do have more phase delay at the low end frequency spectrum. That combined with poor room acoustics sometimes produces boomy bass sound. We have variable extension frequency and damping settings to address that. Customers should experiment with extension filter settings. Low extension setting is recommended for HT use whereas high extension setting (24hz, Q=0.8) is recommend for music.

LV12F 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 LV12F:

Frequency Response LFE In 19 Hz - 300 Hz (+/- 2dB)
Frequency Response Line In 19 Hz - 100 Hz (+/- 2dB)
Woofer 12" paper with custom sensing coil
Woofer Material Black paper with rubber surround, aluminum cast frame, copper flux de-modulation shorting rings
Amplifier 300w RMS Hypex class D servo controlled
Dimensions W x H x D 16" x 22" x 19" - (20-1/2" D with grille)
Shipping Weight 69 lbs each
Crossover Slope 12 dB / octave
Crossover Range (Low Pass) Continuously variable 40 - 120 Hz
Rumble Filter (High Pass) 12db/oct at 20hz to limit subsonic cone excursion
Phase Adjustment 0 - 180 degrees continuously variable
Bass Extension Settings Low (19hz,Q=1.1), med (22hz,Q=0.9), and high(24hz, Q=0.8)
Finish Black Oak, Matte Black
Warranty 5 years on woofer / 3 years on electronics
45-day satisfaction guarantee