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  F12-400 Direct Servo subwoofer
12" sealed audiophile sub (recommend for music and HT)
Our Most Affordable Metal Cone Subwoofer

F12-400, which is a higher power version of F12-300, uses 400WRMS amplifier HX410PEQ with 2 line-in RCA, one LFE RCA, and a one-band PEQ. We recommend F12-400 as an alternative to regular F12 for customers with tight budget. Its lowest bass extension is essentially same as that of F12.

F12-300 Quickguide(retired product)

F12-400PEQ Quickguide
Integration guide

  Description: F12-400 with PEQ, 2 line-in RCQ and 1 LFE Price  
  F12-400PEQ-BO black oak with HX410PEQ 400WRMS amp and 48 states shipping $899 buy it now
  F12-400PEQ-BM black matte with HX410PEQ 400WRMS amp and 48 states shipping $899 buy it now

Performance & Specifications

The extension filter in F12-400 is simplied to 3 positions: Low-Music, Low-HT, and high with frequency and phase response shown below. Low-music has the lowest extension, -3 db @ 17 Hz. The response is flat and extended. For high SPL in movies, we recommend Low-HT mode with built-in rumble filter that preserves the FR to -3db@18hz while reducing potentially damaging subsonic energy.

sealed response

Fig 1.0 - F12-400 Frequency response in Low-Music mode

Fig 1.1 - F12-400 Frequency response in Low-HT mode

The high extension setting further reduces the extension and thermal stress for extended duration of playback

Fig 1.2 - F12-400 Frequency response in High exension mode


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!

With our subwoofers the upper and lower -3 dB points are a very close match to the settings selected. If you set bass extension to 14 Hz, that is exactly what you will get. All this is possible because Direct Servo ensures a stable and flat response.

Another aspect of getting a correct integration is phase alignment. We have written a guide on how to achieve a phase aligned subwoofer. More >

Output, extension and user preferences

We use high quality high excursion drivers which make it possible to achieve high output in a relatively compact enclosure. Only with Direct Servo is it possible to achieve such deep bass extension, high output and very high damping simultaneously. The effective system Q is 0.3. A lower Q factor represents a higher level of damping, indicating control of the cone. A typical sealed subwoofer has a Q of 0.9 and then equalized to Q of 0.7 by DSP or other equalization means. However, that does not alter the native Q value of those subs. Only our direct servo subs achives a native Q value of 0.3 with close-loop servo feedback control.



Driver 12" high excursion with custom sensing coil DS1204
Driver materials Black only anodized aluminum with rubber surround
  Cast aluminum basket
  Aluminum flux de-modulation shorting rings
Amplifier 400WRMS class D Hypex module-based patented servo controlled
Input Impedance 33kohm for RCA inputs; 10kohm for mini-XLR inputs
Dimensions 15-3/4"(W) x 15-3/4" (H )x 17"(D) - (18-1/2" D with grille)
Shipping Weight 68 lbs
Frequency Response 14 - 100 Hz (-3 dB @ 17Hz) with LINE input
14 - 200 Hz (-3 dB @ 17 Hz) with LFE IN
Crossover slope Selectable 12 or 24 dB / octave
Crossover range (Low pass) 50 - 100 Hz (100hz to 200hz range is not usable for this sub)
Rumble Filter (High pass ) 17 Hz 18 dB / octave built-in for Low-HT mode
Phase response 90 degrees phase shift at 20 Hz
Phase adjustment 0 - 180 degrees continuously variable (6ms max delay adjustment)
Bass damping factor settings Q=0.5 for Low-music mode
Finishes Available in black matte vinyl or black oak vinyl
Warranty 5 years warranty on driver and 3 years on electronics
  45 day satisfaction guarantee