Roadster owners deserve great sound systems, too. Alan Hickman, owner of the Audio Shoppe, prepares to install state-of-the-art Arc Audio stereo components in a recently completed 1932 Ford highboy.
Since its inception, hot rodding has been about performance. We modify our cars for various reasons, installing components to make them go faster, stop quicker, or corner more confidently—all to make driving more enjoyable. Of course, another way to achieve that goal is by listening to your favorite tunes on the road. That’s why hot rodders from across the country turn to Alan Hickman at the Audio Shoppe for a custom sound system.
Like any professional engine or chassis builder, Hickman selects the best components for the application when installing stereo components. In the newly built 1932 Ford roadster shown here, the speakers and amplifier are from ARC Audio.
Except for the speakers, the necessary electronic components for the roadster’s sound system were hidden under the seat.
Up front, Hickman installed a pair of ARC Audio coaxial speakers in the highboy’s kick panels. The term coaxial is common in audio terminology for what is essentially two speakers in one unit. This design features a woofer cone with a separate tweeter, providing full-range sound quality and better frequency coverage than single-cone speakers.
For the kind of sound that satisfies any audiophile, Hickman installed a pair of ARC Audio 8-inch subwoofers in an enclosure behind the driver seat. Subwoofers respond to frequencies below the range of traditional speakers, producing that deep bass sound. Placing subwoofers in an enclosure increases the air pressure the subwoofer creates, which we perceive as sound. Without an enclosure, the sound waves from the back of the subwoofer cancel out those from the front, killing the bass.
The installed front speakers look clean and unobtrusive. With the coaxial speakers combined with subwoofers, the sound quality is excellent.
A term often heard in relation to speakers is impedance, which is the speaker’s resistance to current measured in ohms. In simple terms, speakers with lower impedance can draw more current, resulting in louder sound. For example, an 8-ohm speaker will need more power to produce the same sound level as a 4-ohm speaker. The key is to match components, meaning the amplifier and the speakers should be compatible. A unique feature of the ARC Audio X2 600.4 amplifier is its adjustability. Each pair of channels includes a load control switch that can be set to accommodate speakers with a total combined impedance between 2 and 4 ohms (not lower than 2 ohms), with a second setting for combined impedance over 4 ohms.
At the center of the system shown here is an ARC Audio amplifier. It acts like a supercharger for stereo systems, boosting the signal from the source to power speakers and subwoofers—power that most car stereos can’t deliver. Additionally, amplifiers improve sound quality and reduce noise and distortion thanks to advanced electronics.
The ARC Audio X2 600.4 is a fan-cooled, four-channel amplifier. Notice the two large black wires; they are pure copper power and ground conductors connected directly to the battery. The amplifier is turned on and off by the ignition switch, which controls an internal relay.
Something that seems to be missing from this system is an obvious source of music. There’s no radio, tape deck, or CD player simply because none of them are needed. Hidden away under the seat is a small Bluetooth module. It receives a signal from any compatible device, like a cell phone, that has recorded audio. The module connects to the amplifier, which in turn feeds the speakers, creating a clean, unobtrusive sound system.
For gearheads, there’s nothing more enjoyable than cruising in a hot rod. The only thing that could make it better is being able to hear your favorite tunes while doing it, and as we’ve shown here, it’s simple to “tune” up your sound with some sound engineering. MR
On the right is the wireless Bluetooth module and on the left is the subwoofer level control.
Hickman ARC Audio X2, 5.25-inch coaxial speakers for the passenger compartment.
To ensure the clearest sound quality, Hickman placed foam behind the kick panel–mounted speakers to absorb the “back wave” (the sound that’s generated on the back side of the speaker) so it can’t be heard.
With the foam installed, holes for the speakers were carefully cut in the upholstery panel. Since this requires precision, a hole template is included with the speaker.
Another important consideration is securing the speaker to the panel to prevent vibration. Hickman used screws and nuts to fasten the speakers to the Luan (1/8- to ¼-inch lightweight and flexible plywood) backing of the kick panels.
To verify the speakers were connected correctly, red and black wires were used so the speaker input and amplifier output polarities could be identified and matched.
Hickman built this enclosure to hold a pair of ARC Audio subwoofers, shown here from the bottom—speakers facing down.
Since space was limited, Hickman had to build a subwoofer enclosure that fits directly behind the seat and snugly against the battery box.
Housed in the enclosure are two Arc Audio ARC-8 subwoofers. These high-end, 8-inch speakers have a peak power handling of 300 watts.
Making a good connection to the ARC Audio subwoofer is easy with the spring-loaded terminals that securely hold the wire.
ARC Audio’s subwoofers have dual voice coils. Note the jumper wire connecting the plus (red) and minus (black) terminals, which means the coils are connected in series while the speakers are wired in parallel.
Properly wiring the subwoofers is essential to avoid damage to very sensitive and costly components. For those lacking Hickman’s expertise, ARC Audio provides detailed instructions on connection options.
Sealing the subwoofers to the enclosure is achieved by adding a rubber gasket to the speaker’s mounting flange.
Here, the gasket has been installed on one speaker. Note that the number of mounting holes on the flange is equal to the number used to prevent the speaker’s frame from vibrating.
This is the subwoofer enclosure with the speakers installed. Arc Audio provides guidelines for the size of enclosures to ensure the best sound quality.
Hickman used Molex connectors so the subwoofer enclosure can be removed if necessary. The same style connectors were also used on the front speakers.
From the front, the enclosure’s opening, which allows air to escape, is located at the bottom.
To match the roadster’s interior, Hickman had the enclosure covered in black vinyl.
The final step in the installation is to connect the Molex two-pin connector from the amplifier.
Like many high-performance engine components, the ARC Audio amplifier has lots of “tuning” options. Careful, incremental adjustments will yield the best results.
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