Boosting Power and Adding Bluetooth to a Classic Car Stereo

Whether it’s engine upgrades, suspension setup, paint color, or audio system, every car enthusiast has a different idea in mind for how they want their build to go. There is no right or wrong way to build your vehicle, as long as you’re building it how you want it. That said, we’re featuring one of the most beastly-looking period-correct vehicles to ever feature a Clarion audio system.

When it came to this 1975 square-body GMC Jimmy (the Chevrolet K5 Blazer’s twin brother), the owner had done a significant number of upgrades, adding his own personal touch to the vehicle. Those upgrades include a suspension lift, custom bumpers, BFGoodrich All-Terrain tires, engine upgrades, paintwork, and interior work – all of which have kept the vehicle looking period-correct, but not factory original.

When it came to the audio system, he knew he wanted to follow suit with the vehicle’s period-correct theme, but have it powerful enough to overshadow the loud rumble of the upgraded small block V8, and Bluetooth was a must. Like many owners of classic cars, he didn’t want to cut the 42-year-old sheet metal dash in favor of adding a modern single DIN audio source unit, so he opted for swapping the factory AM radio out with a newer GM unit from the late 1980s that offered a more modern AM/FM electronic tuner, separate bass and treble control, the ability to power four speakers, and looked right at home in the factory shaft-mount radio opening of his dashboard.  

While still an upgrade compared to what was in there before, the radio’s only media playback option was a Cassette player, and nobody uses cassettes anymore. Sure, the owner could have bought a cassette adapter, but modern smartphones (such as the iPhone 7) don’t have 3.5mm adapters, and the sound quality you get from those adapters is generally poor. Instead, he installed a high-quality in-line FM modulator that cuts off the antenna feed to the radio when switched on, and connected a 12-volt Bluetooth aptX receiver module to it. While not as ideal as having a radio with Bluetooth connectivity built-in, this compromise performs more than adequately, and delivered exactly what the owner wanted.

Next is where Clarion came in. These trucks came from the factory with a single speaker in the dashboard, and the vehicle actually has no other factory provisions to add speakers. So, with some aftermarket kick panels secured for under the dashboard of the vehicle, Clarion supplied a set of their SRG1623R 6.5-inch coaxial speakers. For the rear interior quarter panels that were custom fabricated by the upholstery shop that did the interior of the vehicle, a set of SRG6933R 6x9-inch 3-way speakers were supplied. With some careful cutting and trimming of the custom interior panels, the speakers were installed and came out looking very clean, almost as if they should have been there from the factory all along.

Even though the GM radio used in this install could power the four speakers on its own, it wouldn’t be loud enough to hear clearly over the engine. The owner wanted to ensure that music could be heard loudly and clearly, and to make sure the speakers were driven with plenty of power for optimal performance, a Clarion XC2510 5-channel micro-size amplifier was used. Because most older radios, especially factory units, do not offer pre-amp outputs, Clarion’s micro-size amps, including the XC2510, work well because they have a high-level input option, allowing audio to be supplied to the amplifier using the speaker outputs from the radio. No need to install line output converters to use these amps. Additionally, these amps are extremely powerful for their small size, and can be easily hidden away, such as under a seat or under the dash. For this install, the amplifier was hidden under the passenger seat, still easily accessible but out of sight and out of the way of passengers.

Once connected, the amplifier gain controls and crossovers were set, offering excellent sound quality and balance between the front and rear speakers. On their own, Clarion’s SRG line of automotive speakers offer excellent performance, but the owner wanted to further boost low-frequency response, and wanted to add a subwoofer. For this, Clarion’s WG3020D 12-inch dual voice coil subwoofer was used.

The Clarion XC2510 amplifier, powering the four cabin speakers, also features a dedicated subwoofer channel, providing up to 300-watts of continuous power at 2-Ohms – more than enough power to set off car alarms. When combined with the other speakers, it fills the large cabin of this classic off-roader with excellent sound quality across the frequency range. Because the owner does take this 4X4 off-road, on camping trips, and sometimes for weekend errands, he wanted the subwoofer to be removable. So, the subwoofer was installed in a removable box that is easily disconnected and removed from the vehicle. Because of this, a nice feature provided by the XC2510 amplifier is its two fuses, one for the four-channels powering the full-range speakers, and another for just the subwoofer. Simply pulling the subwoofer channel’s fuse when the subwoofer is not installed ensures that the speaker wires running to the subwoofer will be completely deactivated.

If you’ve got a classic or modern vehicle that could benefit from an audio upgrade, but you don’t want to part with the factory radio, Clarion has the components you need to get more out of your audio system! The goal of this installation was to maintain the classic feel of this truck’s interior, add Bluetooth connectivity, and boost the power and performance of the audio system. This installation checks all the boxes. Not only will this menacing-looking classic SUV get the owner anywhere he wants to go, on- or off-road, it will now pack a serious audio punch getting there!

Alyson Yarberry