• How to Turn Your Vehicle into a Surround Sound Marvel

    Surround sound is not just for the home or theaters. It can also be experienced in the car. What makes this possible are digital signal processors that automatically adjust to the format that is being played whether it is Dolby, Dolby Digital, DTS or some other format. The processors also include a parametric, paragraphic or graphic equalizer.

    In a surround sound system the data is transmitted in the digital domain. Commonly, the source unit is a DVD player.

    The speaker system is set up similar to the front stage-rear fill but also includes a center channel—a midrange speaker and tweeter—which are installed in the center of the dashboard. The size of the midrange speaker should be the same as the midrange speakers in the doors or kick panels. Moreover, there should be one amplifier dedicated to feeding power to the center channel speakers or a discrete channel from a 5.1 amplifier working the center channel. The amount of power going to the center channel speakers should be the same that is going to the left and right speakers.

    The concept of a good surround sound system is for the music from the various speakers to reach the listener at the same time. In a car, placement of speakers alone cannot achieve this. But the processors include the capability of delaying the sound from speakers that may be too close to the listener.

    It is recommended that tweeters be placed as close to the midrange speakers as possible. Most system installers also recommend that a bass speaker be added to the front of the vehicle. This can be an 8-inch or 10-inch subwoofer. However, it is difficult to place a large subwoofer in the front of a vehicle. Commonly, there is just no room for one. So your system will work just fine without it because the processor will compensate. You can also use a 6.5-inch speaker up front and cross it over at 80 or 100 hertz and let the subwoofers play the real low bass.

    Many manufacturers offer a packaged system while others offer components that can be used to build a surround sound system.

    What Leads to Acoustic Problems

    Soft surfaces like cloth absorb the sound, causing the loss of some frequencies. A hard surface like plastic, vinyl, leather and glass reflect the sound, causing frequencies to bounce around the car.

    The size of the vehicle is an issue because it dictates the location of the people in the listening area and affects how the sound reaches the listener. If the car is large, then the listener may be too far away from the speakers. If the car is small, then the listener may be too close to the speakers.

    The factory locations of the speakers also become an acoustics issue. If speakers are positioned high on the door, they could be too close to the driver and too far away from the passenger on one side and too close to the passenger and too far away from the driver on the other side. If the speakers are located low on the door, they’re farther away from the closest listener, resulting in a better sound. Many factory systems have the tweeters on the dash and the midrange speakers in the doors, putting them too far away in relationship to each other. Experts say that the center of the tweeter should be no farther than 4.5 to 5 inches from the center of the midrange speaker.

    Another issue is whether the car is a hatchback or has a trunk. The subwoofer enclosure is commonly placed in the rear of the car, and the shape of a trunk or hatchback can affect the performance of the system.

    Fixing the Problems

    Here are some things you can do to minimize the problems and maximize the benefits.

    Cover the hard surfaces with a soft material. Improve the location of the speakers. Instead of having the speakers in the door and on the dash, construct kick panels to hold them.

    It may also be beneficial for the speakers in the rear deck to splash sound off the back window, helping to achieve a rear fill.

    Make sure that the rear audio doesn’t dominate the sound coming from the front speakers. Attenuate the rear speakers by adjusting the gain on the amplifier, giving them a little less power.

    If you have a hatchback, position the subwoofers to splash sound off the glass. In a trunk, direct the subwoofers to fire into a three-sided corner (two walls and the floor).

    Include an equalizer in your system. The equilizer can be used to boost the frequencies that are absorbed, and cut frequencies that are reflected. A real time analyzer and playing pink noise through the system can help you make the adjustments.

    So, as you can see, it is possible to enjoy your DVDs with their awesome surround sound in your car and not just in your home.