PASMAG JBL BassPro SL Amplifier Subwoofer Review 10

If you are looking for big bass, but have no room for a traditional woofer enclosure, the folks at JBL might have a solution for you with the new BassPro SL subwoofer system. The system is specifically designed to augment your existing full-range speakers and provide the bass response you’re looking for, while taking up virtually no cargo room.


The JBL BassPro SL is a self-powered and completely self-contained subwoofer system that has been designed specifically to fit into incredibly tight spaces, like the typically wasted space under your seat. By designing the system with a profile height of only 71 mm (2.1875 inches) the subwoofer system will fit under all but the lowest seats. Length and width measure 344 mm (13.5625 inches) and 250 mm (9.875 inches), respectively. Included in this compact form factor are a proprietary shallow-mount eight-inch woofer and an incredibly efficient Class D amplifier rated at 125 watts.

Standard features on the BassPro SL include an adjustable low-pass crossover filter (variable from 50 to 120 Hz) and a bass boost control that can provide additional output at 70 Hz. There is also a 0 to 180° phase switch, so you can listen to it in either position and pick the one that’s best for your specific application. For installation convenience and flexibility, the input signal can be supplied by either a traditional RCA signal or a high-level signal from the OEM system. To ensure compatibility with virtually all OEM systems, a switch provides selection of either 10,000 ohms, or 120 ohms as the desired input impedance of the high-level input. Additional installation convenience comes from the ability to choose signal sensing or traditional 12-volt turn-on functionality depending on the particular vehicle.

An optional wired remote level control (GTO-RBC) is also available to provide level adjustment from the driver’s seat. Connections are pretty simple, with standard terminal strip gold-plated screws for the power, ground and remote wires. The terminals are more than adequate for the low current demand of the internal amplifier, so there is no need for larger than about 10-gauge power cables.

The internal amplifier is a Class D design and has a maximum current draw of less than 12 amperes. It runs very cool and drives a special low-profile eight-inch woofer designed specifically for the ABS enclosure. The woofer is a robust unit with a large 110-mm ferrite motor assembly, weighing in at over 26 ounces. It drives a 38-mm (1.5-inch) four-layer copper voice coil wound on a Til glass fiber former. This moving assembly in turn drives an ABS and polycarbonate cone, which has its periphery anchored by a butyl rubber surround.

The ABS enclosure is very well braced internally and includes dozens of strengthening ribs to prevent unwanted resonances and increase the overall strength of the sealed enclosure. The woofer is also mechanically fastened to both sides of the enclosure, which further enhances the strength and reduces resonances.

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Okay, I will admit that when I was hooking the BassPro SL into my reference system for the listening session, my expectations were fairly low. I mean, this is a single eight-inch woofer in a very small, sealed enclosure. However, when I begin playing music, I’m quite surprised at not only the output of the woofer system, but also the quality of the sound. I expected a fairly boomy output caused by the small air space, not the nice, tight bass I actually hear. Sure, the output tapers off fairly quickly below about 60 Hz, but when all you have is OEM speakers, this system will certainly add a new dimension to your music.

I begin with some well recorded tracks by Dire Straits, Rush and Mighty Sam McLain. The JBL system quickly makes me a believer with its unexpected musicality and rich, warm tone. The woofer sounds quite good, with a level of clarity and definition that I had not anticipated. Moving to more bass heavy music, like Yello and Hot Fire, shows me that the shallow woofer can go decently low and reasonably loud, too; handling the built-in amp’s power with no sign of distress or complaint. Sure, you are probably not going to win any SPL contests with it, but in an average-sized vehicle, the diminutive system should satisfy all but the most “enthusiastic” listener.

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If you are conspicuously short on room for a “normal” subwoofer enclosure and have a few inches of space under your seat that is currently going to waste, you might want to give the JBL BassPro SL subwoofer system a shot. The tiny, self-contained system is surprisingly good for its size, and with an MSRP under 250 bucks (U.S.) you can probably afford to put one under each seat! For more information, check it and the other cool JBL gear out online at, and follow then on Facebook, Twitter and YouTube.

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