Car Active Subwoofer Impedance

Car Active Subwoofer Impedance

Recent technological achievements have led to a trend toward compact active subwoofers with astonishing performance.

Bass enhancement upgrades in a car have aways come with compromise. Often requiring deployment of a sizeable amplifier and a large-coned subwoofer in an enormous enclosure. Naturally, as car owners become more luggage-space conscious and vehicle manufacturers look to add a plethora of energy sapping driving aids, the quest for a small efficient box providing lots of bass output has been constant.

We now see many compact solutions on the market however, many of these are simply miniature versions of old technology and end up too small to work properly. New active subwoofers from the Audison Prima range are very different however. Those who have tried them are very impressed by the bass output and musicality that Audison has managed to conjure up. Available in both 10″ and 8″ versions, these boxes exploit the remarkable properties of Class D amplification coupled with revolutionary dual voice coil subs featuring ultra-low impedance.

As the word suggests, “impedance” in an electrical circuit restricts current flow and therefore power. Car speakers traditionally offer a 4 ohm load to an amplifier. In order to run efficiently, the amplifier output impedance is matched to the input impedance of the speaker. Power output gains can be achieved by lowering the load impedance by connecting two voice coils in parallel for instance but this can lead to issues with heat as amplifier output devices effectively behave like a toddler running down a steep hill. Class D amplifiers allow much lower impedances due to super-efficient circuitry applied. In the case of the new Audison Prima active subwoofers, the impedance of amplifier module output and speaker input is just 0.4 ohms. This greater efficiency means that a much higher output is possible. In turn this super-low efficiency means the speaker enclosure can be made smaller without compromise to low-end reproduction.

The Audison Prima APBX 8 AS measures just 15.2 x 6.22 x 11.73 inches. The amplifier outputs an impressive 250 watts RMS and is still able to be housed inside the speaker enclosure due to 90% efficiency in the amplification and power supply electronics. The high efficiency amplifying circuits mean far less energy ends up producing heat, so huge heatsinks and fans are not required and the overall chassis can be made much smaller. What’s more, there is still room for a 12 dB/octave Butterworth low-pass filter and the unit will accept either a high or low level input. The filter can be bypassed if signal is provided via a sub output on a signal processor.

Solid construction and stunning performance are the keywords here. As always, hearing is believing so head on down to your local FOUR MASTER for a demonstration.

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