The Secret Most Car Audio Shops Won’t Tell You
A well-installed system costing $500 can perform better than a poorly installed, poorly chosen $2,000 system. Sound systems are like water, they will always hit their lowest level no matter how much money you throw into a bad setup.
The ear is the final judge of what sounds good. But to get the best out of whatever system you choose, the installation it’s critical.
Start With Sound Deadening, Not Speakers
Many people underestimate the impact of this step, only to regret it later. Instead of rushing to buy speakers and amplifiers, the first upgrade you should do is to treat your door cavities with butyl rubber sound deadening material to block off vibrational noise in models with low noise control. Stick the material to the inner metal skin of each door panel, it will cover as much exposed metal as you can to reach.
This is an explanation of why it’s more important than you think: sound dampening can reduce cabin noise floors by up to 3dB to 10dB, effectively doubling the perceived power of your existing amplifier without upgrading the electronics (Mobile Electronics Association). A door cavity that is treated also begins to act like an infinite baffle / sealed enclosure for your speaker which massively improves the mid-bass response of even mid-range woofers.
This is money spent on the quality of installation, not on hardware. It is the cheapest single upgrade in a car audio system.
Build Your Front Stage the Right Way
The face of the system. The head unit, the front speakers, and how they interact with each other. Do not even think about subwoofers until this is right.
Head unit: Find one with high-voltage pre-outs. 4V or better. That extra voltage will deliver a cleaner signal to your amplifier and lower the noise floor before it ever gets to your speakers.
Speakers: If your budget will allow, do not use coaxial speakers, use component speakers which physically separate the tweeter from the woofer. This will let you mount the tweeter at ear level on the A-pillar which is what creates a proper soundstage: the perception that the music is occurring in front of you rather than at your feet.
When researching the top speakers for sound quality, ignore anything and pay attention only to the RMS power. Not the peak power. Peak power is a marketing number. RMS is how much continuous power the driver can actually handle and is the only number that matters when you are matching the speakers to the amplifier.
One Amplifier That Does Two Jobs
A four-channel amp will be your best ally in creating a budget-friendly sound system. You can power your front speakers with channels one and two, connecting your component woofers to them while either using full range or a high-pass filter for the tweeters. Then, you have the freedom to connect the two rear channels together by bridging them and power a single subwoofer with that output.
Most quality four-channel amps produce enough power in bridged mode for a small to medium-sized subwoofer, so you won’t need an additional mono-block amp for your sub. One piece of gear, your complete sound system.
A sealed box for your sub offers the best accuracy and tightness for smaller trunk spaces. A ported box is more efficient, meaning it plays louder at a certain frequency, but it is very difficult to design and the port must be the correct length and diameter or the sound gets muddy and uncontrolled. Sealed is the more forgiving first-time builder’s choice.
Use oxygen-free copper wire. Yes, it’s more expensive than copper clad aluminum but that CCA wire is insidiously resistant. Your system sounds great the first day but corrodes and loses clarity every moment after that. Use the proper sized power, ground, and signal cables and connectors. Don’t ground to seatbelt bolts. Don’t use the chassis of the car as a ground for an amp. Don’t daisy-chain multiple devices to one fused link on the battery. Don’t just twist the wires together. Don’t assume anything. Do it correct the first time and you will save money over the long run.
Tune Before You Call it Done
This is the part where most DIY builds start to shudder and fall apart. The hardware goes in, the music plays, and most DIYers will call the build finished. If you want truly professional-sounding results, though, you’ve got one more step to tackle.
You’re going to use the time alignment settings in your head unit to do this. Thankfully, most modern head units have these settings, but you have to go diving into the audio menu to find them. Time alignment is one of the coolest tricks up any installer’s sleeve, and you’re about to school us all on why.
Basically, what time alignment does is compensate for the fact that your left speaker is closer to your left ear than your right speaker is to your right ear. Sounds obvious, right? But think about what that physical discrepancy does to the stereo image, sound from the left speaker gets to your ear fast.The sound from the further away right speaker has to work much harder to catch up, pushing the whole center of the soundstage off to one side.
Great news is that most modern head units have time alignment built-in, and you can start fixing it by slowing down the closer speaker until the signals arrive in your ears at the same time. Boom, instant epic center image. You can’t argue with physics. A rough time alignment setting is actually something you can play by ear, and it’ll create an easily audible difference.
If your head unit isn’t that fancy and doesn’t have time alignment but does include a digital signal processor or even a basic parametric EQ, firing it up to tame any frequencies that sound harsh or boomy in your specific vehicle is a good idea. Every cabin resonates differently. Stop and listen at every stage to everything we’re about to lay down and make sure it all sounds like music to you.
Spend in Order, Not in Volume
The order in which you build your system is just as important. Sound deadening your doors and trunk will make even a factory system sound better. After all, if your car’s interior sounds like a tin can you won’t even be able to hear half your speakers anyway. And no, doors don’t weigh enough for your speakers to pop off. After sound deadening, focus on the front stage including getting better speakers/coaxials if you need them, and proper power delivery to those speakers. What’s the point of adding more power if half of it doesn’t actually go to what you’re primarily listening to? With the front stage taken care of, then upgrade/add an amplifier and subwoofer correcting the low end. A subwoofer sounds infinitely better when it’s hitting the notes it’s supposed to be without conflicting with the midrange coming from your components.
