Mixing Up the Beat

The last decade has seen a veritable tsunami of new audio playback formats. Just when CD audio became the norm, the digital age sprung up on us and delivered formats like MP3, WMA, and the little music player that finally killed the portable CD player: the iPod. Manufacturers of car audio equipment took awhile to take it all in, and now almost all have products that are capable of playing back multiple formats. The main head unit fitted in your car might still be a basic model, which is usually done to cut cost on regular vehicles. Can’t play MP3 and WMA files and want to upgrade your head unit? Here are some things to look out for when deciding what you want.

Ideally, a perfectly setup system will use the head unit to provide a line level signal to external amplifiers and you would not use its internal amplifiers. The usually do not have the power and strength to drive speakers both loudly and cleanly. The line level signal is cleaner than the speaker level outputs on the head unit because it is does not go through the internal amplifiers in the head unit. Purists will always look for had units that have line-level preamp outputs at the back. Even if you do not intend to install an external amplifier now, the presence of the preamp outputs will make it easier to upgrade your system should you wish to do so in the further. You can run speaker level outputs to an external power amplifier, but it is not an ideal situation. Most casual users are perfectly happy with the internal amplifiers in their head units, and there is nothing wrong with that. The main advantages of external power amps are that you can play louder, and the music will sound more detailed and sonically ‘deeper’.

Your head unit is the only part of the car stereo that you interact with, so it is important to get one that "feels" good to you. Always use a head unit in a store display and use it for awhile. Don’t be swayed by the sales pitch before you’ve had a chance to try it out! Ensure that al the audio formats you require are playable, and try to flip through radio stations and tracks on a CD to see if it is quick and easy. If you have problems with small buttons, imagine what it will be like when you are driving! Since many models in the same price range are similar in features and sound quality, usability is often the deciding factor between models.

Casual users who just want some music will not usually nitpick over sound quality, but it must be noted that despite all the innovations that we’ve seen, CD audio is still the most consistent quality playback medium, and car audiophiles swear by it. MP3s and WMA formats have the advantage of smaller file sizes, but it is this same reason that causes the decrease in audio quality, unless you encode them a at a bitrate comparable to CD audio, which would effectively negate their small size advantage!

If you intend to use the head unit as the main source of power, bear in mind that the power specifications given by most manufacturers for head units are not accurate. They often use terms like "music power" or "peak power" which have little real meaning because there is no standard definition of those terms. If the power is quoted in "RMS" terms then it is usually accurate. However, there is still one other place of misconception. Often manufacturers will quote power as "30watts x 4 RMS". The "RMS" seems to mean it is a true indication of power but they are implying that all 4 channels can produce 30watts rms at the same time. With a head unit, this is almost always not true. Because of the small power supplies in head units they can rarely output more than 15-60 watts TOTAL. This means that the power to each channel at maximum loading would only be 1/4 of that total. Some manufacturers are better than others about giving accurate specifications and a few models are available with sophisticated power supplies which have higher power output but they tend to be expensive.

The choice of playback medium is mostly a matter of preference. Even in this day and age, some might want to have the convenience of having a cassette deck in the car. They are becoming quite hard to find though. CD changers are commonly sold as in dash units or remote units mounted elsewhere. An in-dash CD is convenient for changing discs quickly while on the road. Because of size of most CD changers they are usually mounted in the trunk or under the seats although there are models which are small enough to fit in glove compartments. Remember that under the seats or in the trunk are not easy places to get to while you're driving! In car DVD players are also making headway into the scene, but are really useful only when you’re standing still. That can keep children entertained on a long trip, but really, there’s a difference when driving to music or to the explosive soundtrack of an action movie, which some will no doubt find absolutely distracting.

There are many other minor differences in features between head units. Choose the one that appeals to you most. Switch able illumination is nice if you want the head unit's display to match the other instrumentation in your car, but some might find the flashing screensaver type displays too distracting while driving. A remote control can be useful or can be a waste depending on whether you use it. A remote control mounted in the steering wheel can be very convenient though. The bottom line is only get as much as you need, and if you plan on upgrading at a later stage, aim to get parts that have external connection that will not render them obsolete as soon as the next new thing comes along.

Credits: Lionel Kong