Music to Your Ears

Tom Puza, chief engineer audio systems at Delphi Corp., says there are usually two levels of sound systems offered in OEM trucks, “base” and “premium” systems. The base level system are usually less expensive and the premium level systems can be “highly engineered” and composed of a number of high quality components that are all perfectly matched and ideally located.

Puza has a basic idea on the simplest way to get the ultimate in sound. Just specify the best system available when purchasing a new vehicle.

The OEM base system will typically have four speakers. Premium level systems may have six, or even 10-12, plus an amplifier for each one, and they’ll usually feature “total quality and balance of sound right for the vehicle.” Trying to upgrade a premium system is not a great idea, at least accordingly to Puza.

On the other hand, there is a lot you can do to improve the sound of a base level system without either spending wildly or tearing valuable components out of the truck.

Puza believes that the “audio heads installed in trucks are usually good.” He’s referring to the radio or tape deck unit in the dash. So, a good starting point is the speakers.

One way to measure the quality of your speakers is through their “response” or “sensitivity.” Speakers are like engines – some are more efficient than others. Sensitivity is a measurement of “sound power output in decibels (dB) or dB for the power input.” A better speaker has a higher sensitivity number giving you more sound for the same amount of power. Better speakers may also have a better “balance” between bass (the low tones), midrange, and tweeter (higher tones) sound output.

Steve Conner, Delphi’s manager of audio and acoustics, says there are a lot of quality speakers available in the aftermarket that will upgrade original equipment. But, he says, “if your present speaker efficiency is not marked, and they were installed by someone else, you may be shooting in the dark.” This is one time to turn to an audio expert.

The Sony XM Satellite Radio offers a plug and play tuner for vehicle and home.

Amazingly, speaker problems often originate in their covering. When improving your speakers, Conner says, “Your speaker covering must be transparent to sound. And it must not cover any part of the speaker cone or you’ll lose and distort the sound because it will block certain parts of the sound spectrum.

“The speaker grill and trim must be secure to avoid buzzing. Many rattles and buzzes get blamed on the speakers when they are actually trim and mounting-related.” Conner says there are grill cloths and other covers that are “acoustically transparent. If there’s a metal grille, you should be able to see through it easily so the sound will have a good chance to get through.” The safest way to handle this problem is to go with a speaker case with a grill designed for the particular speaker you are installing. “Don’t substitute, if you can avoid it,” he says.

Adding an amp
The next step in upgrading is to add an amplifier between the receiver and speakers. A sensible direction, say Puza and Conner, is to upgrade a typical four-speaker base system by making it into an eight-speaker system. It’s an especially good move, says Conner, because, “a vehicle has a lot of rumble and noise. This can be hard to overcome and doing so takes a lot of power.”

Another problem that can be reasonably easily overcome is the lack of bass power in many trucks that lack deep bass sound output. Connor says your upgrading goal would be to “move more air, and a bass speaker with a bigger diameter than the original speakers will do the trick.”

The simplest way to do this is to install what is called a combination unit known as a “subwoofer box and amp.” The original radio head will then be driving the original four speakers, and the separate amp will be driving the new, low frequency speaker.

One area to be aware of when upgrading, says Carl Mathews, director of merchandising for the Crutchfield Corp., is not to overpower your cab.

Mathews says sometimes it’s enough to just get a small, powered sub-woofer to enhance the frequencies. It makes the music sound better overall, even though it’s affecting only the bass.

As for where to mount the speakers, the Delphi experts recommend that the primary speakers be up front on the right and left, just like a concert stage. Then, you could add rear speakers to add the sensation of having sound all around you.

More options
There is, of course, another way top get more enjoyment out of your sounds system You can increase your listening options, like the increasingly popular satellite radio systems.

If ever there was an electronic invention ideally tailored to trucking, satellite radio may it. Both Sirius Satellite Radio and XM Satellite Radio offer their service for a monthly charge. You need to install an aerial and receiver (“tuner”) first.

There are several advantages to the concept, including the availability of dozens of channels, each with a particular theme. For truckers especially, the most important plus with digital satellite radio is that the signal comes down from multiple satellites instead of having to travel over land. Its strength is nearly constant and it’s only interrupted if there is something directly above you, like an overpass. So, not only is there no fading in and out, you can drive from coast to coast without needing to change the station every couple hundred miles.

Mathews says you must add a tuner (or “black box”) designed for the satellite radio provider you choose, and a controller. The tuner sits out of sight, and has an FM modulator inside that transmits the satellite radio through an unused FM frequency on your radio. You can mount the wired remote controller somewhere near your radio on the dash. It’s what allows you to tune in the satellite radio channels.

Some head units that are two years old or newer have satellite radio capability built in. In this case, you can purchase the tuner and an aerial, and connect them in without purchasing a separate controller.

Mathews says Sony offers a unique satellite radio tuner that offers “plug and play” capability for home and vehicle. You purchase two docking stations and antennas, but can move the tuner between home and the truck. This saves the need for a second subscription to the satellite provider.

This premium CD-changer comes from Delco Electronics.

The cutting edge
If you want to really go all-out, you can take advantage what is describes as the cutting edge of vehicle audio, which blurs the lines between computers and radios.

For example, there’s the Kenwood Excelon KHD-CX910 Music Keg. It’s a state-of-the-art digital media player with an integral 10-gigabyte memory, which enables it to store up to 2,500 MP3, WAV, or Windows Media files for digital playback. The system includes the Music Keg player for the truck (where the hard drive is), a music storage cartridge, and a desktop unit for your home. The desktop unit lets you record music off the Internet via your PC and store it. There’s software that makes it easy to organize the music into folders for quick retrieval. This machine prices out at about $750.

Then there’s the Pioneer DEH-P90HDD, a Hard Drive/Receiver that’s only the size of an ordinary head unit – 7-inches long, 2-inches high, and 7-inches deep. The unit, priced at about $2,000, allows you to record music from the Internet with your PC just like the Music Keg, then bring it to the unit with a tiny Sony memory stick the size of a piece of chewing gum. You can also put CDs in and record them. This hard drive also has a 10-gigabyte capacity. The unit has XM Satellite Radio reception capability and a remote controller.

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