Since the late ’80s, the car audio industry has experienced incredible levels of growth. New technology and features have expanded our opportunities to increase sound quality and enhance entertainment. What hasn’t changed are the core building blocks of how sound systems are designed.
Every system starts with a source. We call this the head unit, source unit or radio. In more than 99.9% of vehicles, the source unit includes an AM/FM receiver, along with a CD player or USB port to play digital media files like MP3, WMA, AAC and FLAC files. The source unit also typically contains the volume control for the system.
It used to be that a new source unit was the first component that would be upgraded on the path to improving the sound system in a vehicle. From the perspective of a quality improvement, this is becoming less and less common. Read on to find out about the benefits and limitations of replacing the factory radio in your vehicle.
Can I Make the Switch?
Look at a vehicle like a BMW, Audi, Mercedes-Benz or even a Mazda. Their radios are not stand-alone units at all. The Mazda 3 is an excellent example of a modern distributed source unit. There is a screen on the dash, a CD mechanism below the climate controls and a control panel in the center console. None of these components matches any size standard for an aftermarket radio. If you want to upgrade the sound system in this vehicle, you will not be buying a new radio.
Thankfully, this radio has most of the features that people want. CD, MP3, SiriusXM, an auxiliary input and Bluetooth audio streaming are readily available signal sources. The system includes hands-free calling and a built-in GPS-based navigation system.
Sadly, though, the system does not include Apple CarPlay or Android Auto smartphone integration.
Can We Integrate?
If we want to upgrade the sound system, a mobile enhancement retailer can connect an amplifier and new speakers to the signal coming out of the radio. With some fine-tuning and a well-executed speaker installation, the quality of the system will improve. You will also be able to turn your music up louder.
If you want to take things to the next step, then add a digital signal processor (DSP) to give your installer all the tools required to flatten any peaks or dips in the system’s frequency response and adjust for different path lengths between the listening position and your speakers.
The Sound Quality Upgrade Path
Let’s look at another popular compact car: the Subaru Impreza. Subaru manufactures durable, reliable vehicles, but their sound systems are not at the forefront of technology. In fact, several models of the Impreza are begging for sound system upgrades. Luckily, improving the sound systems in these vehicles is easy. Let’s look at what’s lacking and how to fix it.
Add Bass, More Power and New Speakers
The recipe for improving the performance of an audio system does not vary much from vehicle to vehicle. The first step most retailers will recommend is to add an amplifier and a subwoofer. Adding a subwoofer will not only bring more bass to the system to make it sound more lifelike, but alleviates the need for the smaller speakers and factory amplifier to try to reproduce those frequencies. The result: Everything sounds better.
The next step is to add more power to the factory speakers with an amplifier. Many people will combine the addition of a subwoofer with a multichannel amplifier that can power the factory speakers at the same time. Five-channel amplifiers are an excellent choice for a single, easy-to-install upgrade. Multichannel amplifiers have built-in crossovers that will eliminate bass information from the smaller speakers, so they sound better.
The last step in upgrading the sound system is to replace the factory speakers. Now, if you have listened to a factory Subaru stereo, this might be your first step. There is no right or wrong when it comes to the upgrade path you take. Keep reading to find out why we often leave this step to the end.
We often suggest upgrading the speakers last because high-end speakers aren’t typically as efficient as the cheap speakers that come from the factory. New speakers provide smoother frequency response and much less distortion, and can handle a lot more power and play louder. When connected to a factory radio, there isn’t have enough power to experience all of the benefits of the new speakers. A speaker will only play loud when it is driven with adequate power.
Wait – What about the Radio?
You will notice that nowhere in the upgrade path did we suggest replacing the radio. The factory Impreza radio has a reasonable feature set and provides perfectly flat frequency response that we can use to improve your system. When looking at the goal of improving the sound quality of the system, the source unit is the last thing to change (unless you want to add high-resolution audio playback).
I Want More Features!
We touched on Android Auto and Apple CarPlay. These technologies, along with Siri Eyes Free, FLAC file playback, Pandora and much more, are great reasons to upgrade a factory radio. However, these are not specifically performance improvements – they are feature enhancements. We could nit-pick about FLAC files sounding better (in a future article, we will analyze high-resolution audio in great detail.) If you want better sound, all the other upgrades offer a larger increase in performance for your investment than an aftermarket source unit.
Experience Better Sound
When it comes time to upgrade the sound system in your vehicle, visit your local specialty mobile electronics retailer. Let them know what your goals are for the system and work with them to design something that meets your expectations and your budget. Following our suggested upgrade process can yield impressive improvements with a reasonable investment at each step. Each upgrade will produce immediately audible benefits.
Have fun improving your mobile sound system!
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Sony has been steadily increasing its share of the head unit market with the introduction of feature-packed solutions that continue to give consumers the connectivity and source options they want. The latest addition to Sony’s source unit offerings is the XAV-AX5000, a 6.95-inch multimedia receiver with Apple CarPlay, Android Auto and Bluetooth. The 
Sony calls the display on the AX5000 bezel-less. The trim panel around the display is only a few millimeters thick and gives the unit a very clean and tidy look once installed. The display has a resolution of 800 by 480 pixels and uses a capacitive touch panel. Unlike resistive touch panels that have a plastic texture, a capacitive display is the same as what we are used to on our smartphones — crystal-clear images with a very responsive touchscreen interface.
As mentioned, the XAV-AX5000 includes Android Auto and Apple CarPlay smartphone integration software. If you haven’t experienced these interfaces, they make it very easy to make phone calls, listen to and send replies to text messages, choose the music you want or get navigation directions to almost any address in North America. The interface uses Siri or Google Assistant voice recognition software to perform the majority of functions, so you can keep your eyes on the road and your hands on the wheel.
The XAV-AX5000 includes two USB ports on the rear of the chassis. USB 1 is compatible with iPhone and Android smartphone devices for CarPlay and Android Auto. USB 2 takes care of connecting a USB memory stick to to play MP3, WMA and FLAC digital media files. USB 1 supports WAV, ACC, MPEG-4, WMV, MKV and Xvid files as well. Audio files can have a maximum sampling frequency of 96kHz and video files can have a maximum resolution of 1280×720 pixels.
The XAV-AX5000 includes a dedicated backup camera input with trigger wire to allow you to see objects or people behind your vehicle when parking or maneuvering. The system also includes an external Bluetooth microphone for excellent voice recognition and Bluetooth call quality. Finally, the system is compatible with the majority of factory-installed steering wheel mounted audio controls using a third-party interface, or by using the Custom Steering Wheel Control set-up on the radio itself.
