Introduction

All car audio aficionados like great bass. Just listen out your window when driving to hear someone a block away, with his pounding subwoofers. So, how do you get bass like that when you don't have the depth space to install big drivers?

Answer: The Earthquake SWS.

The Design

The SWS (Shallow Woofer System) line is designed to have the smallest mounting depth possible, without loss of extension.

In cars, mounting the drivers can be the single largest problem to proper imaging. Mounting bass drivers up front is not only a problem, it's almost unheard of.

In comes the SWS.

My Chevrolet Corvette came with anemic 8" drivers, and a conventional 8" aftermarket driver can't fit in the shallow 3" mounting depth.

In comes the SWS, again.

The 8" model only requires 2-1/8", the 10" (reviewed here) only 2-11/16", the 12" only 3", and the 15" (yes 15") only 3-1/4".

A 15" subwoofer driver that will fit in a 3-1/4" depth space? Whoa there Nellie!

The large rubber surround allows an excursion that rivals full height woofers. While the large surround does reduce the effective piston diameter, it adds significant displacement capabilities. The dust cap is of a very contemporary design, namely extruded aluminum. It looks cool, and once the subs are mounted, no one would guess that they are the shallow depth design. And after your friends hear them, they will wonder how you got such a power house in that small space.

The only design detail that I could nit pick with on the SW-10 are the speaker terminals. They are not very beefy, and require soldering to create a satisfactory connection.

The 1000W.2 power amplifier delivers 175 watts rms into the 4 ohm load of each SW-10 subwoofer. It has a variety of filter settings. It can, of course, be used for powering the main audio, but we used it here for the subwoofers. Earthquake has more powerful amplifier models to choose from as well, including monoblocks if you only want to install one sub.

The Enclosure

Earthquake provides several box designs on their website (HERE). They recommend 0.33 ft³ for a sealed enclosure, using the SW-10. I built a square box design, for two woofers, each in a separate chamber. With a space between them for the amplifier, the unit is compact enough to fit between the wheel wells of a small SUV, and shallow enough that it only consumes 6" of trunk space.

The final result was a box that was shorter than a CD case! Use sealant between all sheets, and caulk all corners.

If you don't want to build your own enclosure, there is a company named Pro Box Rocks that makes enclosures designed around the shallow mounting depth of the SWS. The results are truly amazing. This box (photo below) was designed for the new Avalanche and Escalade. They offer several vehicle designs that are very innovative.

Listening tests

I put the enclosure and amplifier in the back of a small SUV. The combination of the earthquake amplifier and two subwoofers is a good match. The amplifier was powerful enough to drive the speakers beyond their limits. The sound was good, and had all the components of a quality product. I would recommend this sub for pop and rap fans, but I think it might be a little loose for classical fans. I had the subs crossed over at 80 Hz low-pass. The subs hit 113 dB, with cabin gain, and that is plenty of SPL for anyone.

THD tests were performed at 31.5 Hz, with a 500 Hz low-pass for the amplifier. Best THD was reached at 92 dB out of car. While I think that the THD could be cleaned up a bit with better box design, these values are probably what most consumers would see with a decent install.

In the graph shown below, THD was measured at 100 dB SPL.

Conclusions

While the SWS-10 might not have the output of a larger sub, in many cases you would never even be able to install a conventional subwoofer driver in the first place. The SWS line opens many installation opportunities, and provides a great quality sound.

The PH 1000W.2 power amplifier is very flexible in the set up for use with subwoofers, and delivers plenty of juice to the SW-10s.

What is really important is the possibility of bringing the sub-bass and bass ranges in for better imaging. Earthquake has done a great job delivering what most would consider impossible, big sound from a really small space.


- Brian Weatherhead -