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F12 Subwoofer

Please Note: There is no difference between the F12 and F12SE other than the piano black finish
12" Audiophile Direct Servo Subwoofer

Designed specifically for discerning listeners who simply demand the absolute best sound quality possible. These advanced subwoofers are in a class of their own and you owe it to yourself to hear the difference of Direct Servo.

arrow Patented Direct Servo technology
arrow 370 watt, PEQ3 class A/B amplifier
arrow Adjustable damping and 1 band PEQ

arrow Save $$ when purchasing dual subs*
arrow Save $$ when purchased with speakers*

*discounts will appear in shopping cart, one discount only, exclusive of sale items

*Black Matte matches our 170/340/200 speakers

arrow Free continental US ground shipping
arrow 45-day satisfaction guarantee
F12 Black Oak F12 SE Piano Black F12 Woofer F12 Amplifier F12 Subwoofer

For audiophiles and enthusiasts looking for uncompromising accuracy in an elegant package, the F12 Signature Edition subwoofer is the ultimate choice. It features Direct Servo™ to ensure accurate frequency and transient response, precise detail and extremely low distortion levels at even high output levels. As a discerning listener you appreciate that bass is the foundation of a satisfying music or home theater experience. You also appreciate that there is more to a home theater subwoofer than shaking the room, and that music can be far more satisfying with a subwoofer that can play deep.

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 subwoofers do exactly what we claim. In the chart below, with bass extension controls set to 14 Hz, the response is 3 db down at 14 Hz. The response is flat and extended.

F12 Response Graph

The new A370PEQ3 amplifier, now shipped standard with F12 and F12SE, has an additional low pass filter setting --LFE. It extends the upper end -3db extension to 200hz.

F12 Response Graph

Unique bass extension controls:

All of our subwoofers feature unique bass extension controls which are not normally found on consumer subwoofers. This enables the user to customize the output and extension to achieve the best compromise in any room. Most subwoofers neglect to provide bass extension control, and the result is that dynamic headroom is compromised.

F12 ControlsThe bass extension controls enable the user to customize the frequency response of the low end. This puts control back in the hands of the user. The controls customize a high pass filter, which attenuates frequencies below a given frequency. If set to 14 Hz, bass below this point will be filtered. The damping control determines the slope, high damping providing the steepest slope.

Parametric EQ:

F12 ControlsA defeatable one band parametric EQ with adjustable frequency, gain and bandwidth means you can not only control the frequency boost or cut, but also the width of the filter.

Additional bass management options are also provided. A switch allows the user to select a 12 or 24 db/octave crossover slope setup option. Where the higher slope (24db/octave) is selected, the amplifier uses a variable 12db/octave filter in addition to a fixed 12db/octave filter. One can choose with a switch the corner frequency of the fixed filter as either 50 or 80 Hz, which will suit most situations. The variable filter can be used for fine tuning.


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 F12 / F12SE:

The standard amplifier is now the A370PEQ3 (370WRMS PEQ). The quickguide for the PEQ3 amplifier for sealed subs can be found here. PEQ3 amps do not have high pass filter RCA outputs but now feature dedicated LFE inputs allowing for easy integration of a 2-ch-plus-HT system setup. PEQ amplifiers are still available in limited quantity for those who still need high pass RCA outputs for non-AVR and non-prepro setups.

Frequency Response (Anechoic) 14 Hz - 100 Hz (-2dB @ 14 Hz)
Woofer 12" high excursion with custom sensing coil
Woofer Material Black or silver anodized aluminium with rubber surround, Cast aluminium basket, Copper flux modulation shorting rings
Amplifier 370w RMS class A/B servo controlled
Maximum Short Term Peak Power Greater than 500 watts
Dimensions W x H x D 15.75" x 15.75" x 17" (18-1/2" D with grille)
Shipping Weight 80 lbs each
Crossover Slope Selectable 12 or 24 dB / octave
Crossover Range (Low Pass) Continuously variable 25 - 100 Hz
Rumble Filter (High Pass) 14 / 20 / 28 Hz 18 dB / octave
Phase Response 90 degrees phase shift at 20 Hz
Phase Adjustment 0 - 180 degrees continuously variable
Bass Damping Factor Settings High (Q=0.5), med (Q=0.7), and low (Q=1.1)
Finish Piano Black or Black Oak
Warranty 5 years on woofer / 3 years on electronics
45-day satisfaction guarantee