The FR of G25 is almost identical to E15HP2 as G25HP uses dual independent servo controllers for each of DS1520 drivers, same as the one used in E15HP2. FR plots will be added soon.

Integration

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.