The JBL GT-BassPro12 doesn't just look intimidating with its silver protective bars and molded woofer, but it sounds intimidating. With a 12-inch woofer and a massive Slipstream front-facing port, the performance is big and aggressive. This subwoofer moves more air than any other subwoofer I tested. It's not as tight and accurate as the sealed subwoofers I tested, but then, it's not designed to be accurate. It's designed to announce your arrival by rattling the skulls of everyone you pass.
The MSRP for the GT-BassPro12 is $249, but the current market price is about $199. This still makes it one of the most expensive powered subwoofers, comparable to the Rockford Fosgate P300. That said, these subwoofers are very different, as they are both designed for very different types of bass. In addition, the price is still a big value when compared to the cost of buying the subwoofer, amplifier and enclosure separately.
To test the audio performance, I listened to the GT-BassPro12 perform with two high-end car speakers. Then I disconnected the speakers and evaluated the isolated bass, listening for unusual distortions, clipping and other nuances. With a ported enclosure, it's not fair to evaluate the performance of the GT-BassPro12 within the same context of a subwoofer with a sealed enclosure, as each is engineered for different types of performances. As such, I evaluated this JBL subwoofer according to how it performed as a ported subwoofer.
The overall performance received an A+ grade. Sure, it wasn't as tight or accurate as the Rockford Fosgate P300, but as I mentioned, it's not designed for this. The Slipstream port is large enough for me to put my fist into the enclosure and it's lined with smooth plastic with rounded edges, creating less drag on the air. This creates a punch on the kick drum nearly strong enough to knock me over. I typically prefer tight and accurate bass because this tends to fit into a mix better for my preferences, but this subwoofer has a lot of fun in it. It was the only subwoofer I tested where I spent additional time listening to it. The feel of the double-kick drums punching my chest on the chorus of Clayman by In Flames, for example, took me back to the feeling of their live concert.
The size of the sweet spot is also impressive. While the volume didn't reach as high as the Rockford Fosgate P300, I could feel the bass just as far away. This subwoofer moves so much air with the woofer and the port, the bass travels well. It's plenty big enough to announce your arrival.
It's disappointing for the frequency response to bottom out at just 35 Hz. For reference, the lowest a human can hear is 20 Hz and the lowest note on a piano is 27 Hz. That said, the lack of 15 Hz is noticeable.
Power & Control
At 150 watts of continuous power, the JBL GT-BassPro12's built-in amplifier is only half as powerful as the Rockford Fosgate P300 and the Pioneer TS-WX1210A. However, since it's a ported enclosure, it doesn't need as much power to achieve massive sound. The port equalizes the air pressure inside the box with the atmosphere, allowing the woofer to move more freely so it's far more efficient at creating noise with its 12-inch woofer.
The controls received an A- grade. The knobs are easy to grip and adjust. The low-pass crossover provides control between 40 and 200 Hz, allowing you to dial the bass in to your preferences and specific acoustic needs. You can boost bass by 12 dB, and it comes with a remote to adjust volume levels from the driver's seat. However, the panel is on the backside, making it difficult to access once it's installed.
As with other 12-inch subwoofers, the size of the GT-BassPro12 is a concern. It requires a trunk or storage area installation, requiring you to sacrifice space for bass. If this is a concern, an under-seat subwoofer is a good option.
The JBL GT-BassPro12 features a 12-inch subwoofer and a 150-watt amplifier. Don’t be fooled by the power output, this subwoofer produces big, aggressive bass. It's not as tight and accurate as a subwoofer with a sealed enclosure, but it's not designed for this type of bass. The Slipstream port isn't for everyone, but it's certainly one of the most fun subwoofers I tested.