How to improve your car's stereo imaging and soundstage

Why car soundstage is hard to get right

When you listen to tunes at home, you probably don't make a habit of planting yourself smack dab in front of your left speaker. If you did, you'd be missing out on the detail the right driver has to offer, as well as the spaciousness of a complete stereo image. Yet when you listen to music in the driver's seat of your car, and you have conventional speakers in your doors or dash, you probably get the same type of imbalanced listening experience.

Add to that the fact that your vehicle interior is mostly glass and plastic, which are reflective, and fabric or leather, which are more absorbent, and the sound waves just get bounced and absorbed randomly throughout the listening environment.

The disadvantages of "side-biased" listening

The music on your left reaches you before the music on your right. Within certain bandwidths, this imbalance may seem to alter your system's response, emphasizing some frequencies over others. The sounds on your left may also seem louder, distorting the soundstage.

Equalizing the lengths of sound paths

To get proper imaging, the path lengths between your speakers and your ears need to be as close to equal as possible. These paths should be unobstructed as well. If your left door speaker lies about two-and-a-half feet from your left ear and your right door speaker about five feet from your right ear, you won't hear balanced sound. Playing with the receiver's balance control can help the driver's listening experience, but it throws the image out of whack for the person in the passenger seat.

Use time alignment to fix the soundstage

You can overcome unequal path lengths by purchasing an in-dash stereo with digital time correction. Time correction allows you to compensate for speaker placement by adjusting the speed at which the audio signal reaches individual speakers. Using the speaker furthest from your ears as a reference point, you calculate the amount of time that speakers closer to you need to be delayed so that all sounds arrive at your ears at the same time.

You can also find time alignment tools in outboard digital signal processors (DSP) or amplifiers that have a built-in DSP. More on this topic below.

Some digital signal processors can dial in your vehicle's sound — including time alignment — using smartphone apps or a connection to your laptop.

Component speaker systems help the staging

Component speaker systems can help because they let you mount the tweeters higher in the vehicle. The higher musical frequencies are more directionally oriented, so having tweeters mounted on the upper door panels or in the dash corners automatically raises the overall soundstage. Many component sets also let you adjust the firing angle of the tweeters to further optimize imaging. (Keep this feature in mind when shopping for add-on tweeters.)

Read our guide to tuning your car speakers for details.

Rear fill — why do you need rear speakers?

If you want the soundstaging to appear on the dash, do you even need rear speakers? We say yes.

Once you have your front speakers installed to your liking, you'll want to make sure that your rear speakers are doing their part to create an ideal soundstage. While personal taste plays a role here, most experts agree that you should adjust the volume level for rear speakers so that you're barely conscious of their presence.

While your front speakers should give you the best midrange and high frequencies possible, your rear speakers can be conventional coaxials or low frequency drivers. Their purpose is to add ambience and depth to your forward soundstage. If they reveal too much high-frequency information, they'll "pull" the stereo image to the rear of your vehicle, away from where you want it.

Pioneer SPHERA adds Dolby Atmos® to the mix

Pioneer's new SPHERA technology brings the spatial audio experience to traditional four-channel car audio using autotuning calibration inside your vehicle. Once SPHERA has analyzed your car's interior, your car's four speakers can play Dolby Atmos encoded music for enveloping audio with a raised soundstage and dramatic channel separation.

Read our expert review of Pioneer SPHERA for more on how this technology performs.

How to adjust the bass

If you're running a subwoofer in your trunk, you want to avoid the sensation that all the bass is coming from the rear of the car. You don't want it sound like the bass player is dancing her way from your trunk to your front doors as she plays higher up the neck.

Whether the crossover is in your amplifier or in-dash stereo, set the high-pass filters to feed your front speakers the lowest frequencies they can safely handle. Start with your low-pass filter set as low as possible, then raise the crossover point until you hear the "sweet spot" — the point at which the bass notes sound clearly defined, punchy, and in front of you. This setup allows some bass to filter from your front speakers and restricts your subwoofer to the low bass that is very difficult to localize and that it's built to deliver.

Read our guide to tuning your subwoofers for details.

DSP for the win

Today, we are fortunate that many amplifiers have built-in DSP — digital signal processing. An amplifier with built-in DSP or an outboard digital signal processor both do the same thing: they let you adjust and tweak the sound to improve soundstaging in your vehicle.

Many of these systems have computer or smartphone apps to help you tune the sound in your vehicle, taking into account your speaker placement, gear, and power. Once you've spent some time getting familiar with the DSP settings and controls, you can create a truly fine-tuned sound in your vehicle.

Learn more about digital signal processors and how to add them to your system.

Quick steps to good soundstaging

Here is a step-by-step process to creating proper soundstaging in your car.

1. Set the stereo's balance and fader controls to 'flat' or 'center'. Turn off any EQ curves or bass boost. You want to start with your stereo's plain, neutral sound.
2. Increase the tweeter level (if possible) or fade the sound slightly forward.
3. Turn down the rear speakers so that you barely notice them. This is also achieved by adjusting the fader toward the front if you don't have specific front/rear volume controls.
4. Use time alignment (either in your stereo or your DSP) to remove side-bias effects. You want sound from the left and right speakers to reach your ears at the same time.
5. Use your subwoofer amp's crossover to tighten up the bass.
6. Adjust your EQ to remove any harsh high frequencies and make subtle tweaks as needed.

Play a variety of your favorite music as you dial in and finesse the settings with your EQ. You'll be surprised at how much of a difference this process can make. Don't worry about trying to get things perfect. Focus on making your music sound fully present, in front of you, with the individual instruments clearly placed across the dash.

Common mistakes when sound tuning

We've already mentioned this stuff above, but it bears repeating. These are some of the most common mistakes people make when tuning their audio system.

• Too much bass. If the subs are slammin' in the back, it spoils the illusion of having the band localized in front of you. And that instense bass can overwhelm the higher frequencies.
• Too much rear fill or overly relying on rear speakers. If the audio from your rear speakers is too strong, you end up with the sound stage behind you. Instead of being in the front row, it feels like you're standing with your back to the band.
• No time alignment. Without proper time alignment, the sound from the left speaker reaches your ears a fraction of a second faster than the right. That makes the notes and instruments playing through the right speaker sound weaker and less prominent.

Testing your system

When you have all your components in place, test your system to see that it's imaging properly. Spend some time listening to other people's set-ups, too. Rather than attempting to precisely duplicate the systems you like, try to pick up general concepts and techniques, keeping in mind that every vehicle differs acoustically. What sounds great in a trophy-winning Camaro may muddy up the sound of your BMW. Besides, some of us like very precise imaging, while others among us prefer sound that is a little more spacious and open.

In the final analysis, the stereo image that suits your tastes is the one that's right for you. So, trust your ears.

Next steps — updgrading and tuning your audio system

If you already have a great sound system in your car, that's awesome. All you need to do is apply the concepts above. If you need new speakers, a stereo with in-depth sound controls, or an amplifier with built-in DSP, contact our expert advisors. They can help find the gear that will work in your vehicle and will do what you need it to do.

And when you purchase your gear from us, you'll get access to our tech support team. They'll help you install it and set it up properly, and even help walk you through tuning it perfection.