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  E15 Direct Servo subwoofer
15" compact high power sub
Performance & Specifications

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.

Fig 1.0 - E15HP Frequency response chart - LINE-IN 14hz high damping

The frequency response with LFE input is shown in Figure 1.1.

Fig 1.1 - E15HP Frequency response chart - LFE-IN 14hz high damping

Looking at the frequency response you will notice that this is not a one note boom box designed to impress with exaggerated bass. Unlike conventional subwoofers, the frequency response remains flat at all output levels until the output limits have been reached.


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 subwoofer has a Q of 0.707 and some achieve a Q as low as 0.5. The penalty is that the box is larger and the output is lower in order to achieve lower damping, but Direct Servo can achieve much lower damping without sacrificing output and making the box bigger.

When more output than one subwoofers can provide is desired, it may be tempting to look for a higher output option. Our subwoofers represent what we consider to be the output limit for an affordable and accurate subwoofer. It's possible to get higher output with one subwoofer, but not without significant compromise and additional cost. We suggest multiple subwoofers as a much better option. A side benefit is that this can also improve the integration with the acoustics of each particular room.

The bass extension controls allow the user to customize the deep bass extension and the rumble filter to control cone excursion. For high SPL, one can set a higher cut off. For music one may prefer a lower cut off. Changing the settings can also result in a better integration with the acoustic gain of the room.


Driver DS1510 15" high excursion with custom sensing coil
Driver materials Black anodized aluminum with rubber surround
  Cast aluminum basket
  Copper flux de-modulation shorting rings
Amplifier 600 RMS class H patented servo controlled
Dimensions 17"(W) x 19 " (H )x 19"(D) - (20-1/2" D with grille)
Shipping Weight 104 lbs
Frequency Response 14 - 200 Hz (-2 dB @ 14 Hz) with LFE inputs in A370PEQ3/XLR2/XLR3
14 - 90 Hz (-2 dB @ 14 Hz) with LINE IN inputs in all models
Crossover slope Selectable 12 or 24 dB / octave (PEQ and XLR versions)
Crossover range (Low pass) 25 - 100 Hz
Rumble Filter (High pass ) 20 Hz 18 dB / octave
Phase response 90 degrees phase shift at 20 Hz (measuring mic has 18 degrees shift)
Phase adjustment 0 - 180 degrees continuously variable
Bass damping factor settings high (Q=0.5), med (Q=0.7), and low (Q=1.1)
Finishes Available in black matte vinyl or black oak vinyl
Warranty 5 years warranty on driver and 2 years on electronics
  30 day satisfaction guarantee