With factory audio systems harnessing more and more popular features found in aftermarket products, integrating peripheral audio equipment with the factory source unit has become an accepted option. In Truckin' Volume 33, Issue 8, "Integrating with OEM, Part 1," we touched on interface solutions for connecting aftermarket products, such as iPods and MP3 players, along with interface solutions for steering-wheel volume controls, video, and head unit swaps. In this issue, we'll cover an OEM integration that allows you to keep the factory source unit intact while you upgrade your amplifier and speakers.
Sound Decision
Many of today's factory head units are loaded with conveniences and features you like, so it makes no sense to replace them for comparable aftermarket pieces. The decision to replace may be further compounded by the assimilation of the factory unit, many of which have become so seamlessly integrated with the dash that replacing them could require a great deal of customization and/or alteration. If you're reading this column, the chances are you are looking for a solution to upgrade your amplifier and speakers with high-quality aftermarket gear. To do so, you'll have to get integrated.
Connecting
There is one outlining problem in connecting a radio-back system to your factory source-the signal outputs. Factory head units are not equipped with RCA outputs-a low-level and low-voltage signal used by aftermarket audio electronics. In most cases, the only signal available is an amplified and high-level one. To rectify this, a high-to-low level converter can be used, but beware: Not every converter is right for every system. If you want your high-performance aftermarket audio products to really perform, you need to use the right OEM integration piece.
If your ride came equipped with the standard audio package, integrating your aftermarket amps should be relatively simple. Most standard audio systems consist of four channels of operation. Adapting aftermarket amplifiers into this system can be done by using a simple line-level converter, such as a standalone unit or one built into an amplifier, and then tapping into the factory speaker wires. This will supply your amplifier with a usable low-level input signal.
But what do you do if your vehicle is equipped with the multi-channel audio upgrade package from the factory? This is where things become more complex. For example, let's say the factory system consists of a three-way speaker system in the front with six amplified channels powering those speakers, or one amplified channel per speaker. Naturally, this system will use a crossover network as the speaker system will consist of a pair of tweeters, midrange, and woofers. Because of this, simple line-level converters will not be very useful-unless your speakers require the exact same crossover points as the original units, which is highly unlikely. In order to get a useful signal, the three channels, left and right, must be summed into a stereo pair. Summing the channels will provide a signal that covers the full audio spectrum, rather than the individual crossed-over segments from each of the six original channels. Products such as AudioControl's LC6i and LC8 provide this basic channel summing capability for a variety of applications.