Audio tuning 101 for the tech-savvy

Looking to get the best out of your car speakers? Here is an overview on speaker calibration from our in-house Pioneer experts.

Some say speaker calibration is a science, while others claim it is an art. Regardless of which camp you are in, speaker calibration is very important in helping you get the most from your audio system. Just like our homes have different layouts, furniture and materials, every car has different acoustic characteristics which tend to skew or “colour” the original sound signature of a speaker or subwoofer. Calibrating your speakers helps to minimise this issue by smoothening out the dips and peaks in the audio levels.

Follow the steps below to get the most enjoyment from your car audio system.

Step 1: Prepare for calibration

Before you start the calibration process, you need to prepare your audio system to receive the adjustments properly.

1. Disable all audio enhancement functions of the receiver, such as loudness and bass boost
2. Reset the graphic or parametric equaliser – set the sound preset, if there’s one, to flat or neutral
3. Turn your smartphone into a sound pressure level metre with free applications (app) like Decibel X 
4. Download a real-time analyser app to measure and study the frequency response of your sound system

Step 2: Dial in the crossover
Once you’ve set up your audio system for calibration, you can begin the process by first dialling in the crossover. A receiver’s crossover setting defines the frequency at which the audio signal of your music track is divided between the speakers and sub. When properly tuned, it ensures an almost seamless sound integration and transition between the two.


Pioneer Z-series TS-Z65F

Take Pioneer’s latest flagship Z-series TS-Z65F (with a frequency response of 32Hz to 96KHz) speakers and TS-Z10LS4 (20Hz to 3.8kHz) subwoofer as an example. On paper, there is obvious overlapping between 32Hz and 3.8kHz, which can lead to too much muddy mid-bass if you set them up together for your sound system.

To solve this issue, you can set the crossover between 80Hz and 120Hz. This way, only the deeper bass signal is sent to the sub. Selected Pioneer receivers, like the Pioneer AVH-Z5050BT, go one step further with independent high- (HPF) and low-pass filter (LPF) settings. HPF sets the lowest frequency that will be routed to your speakers, while LPF determines the highest frequency fed to the sub.

For maximum performance, let the TS-Z65F speakers handle the mids and highs by setting the HPF to 250Hz. Meanwhile, the lows will be catered for by the TS-Z10LS4 subwoofer with LPF at 200Hz. The 50Hz gap provides better separation between the sub and speakers as audio signal rolls off gradually instead of completely.

Step 3: Balance the levels


Screenshot from Decibel X – a good SPL app you can use to calibrate your Pioneer car sound system

Now that you’ve dialled in the crossover setting, the next step is to match the output of the speakers and sub. This can be achieved using your receiver’s speaker level option and Decibel X or any SPL app – a combination of both eliminates guesswork by letting you measure the volume of each speaker and sub. Most car receivers can also generate a test tone such as pink noise to help facilitate the tuning process.

To begin balancing the levels, first increase the receiver’s volume until the app registers around 75dB or at the reference level. Then, turn up or down the level setting for each speaker and sub until they are all within a 1 or 2dB variation of each other. There should be a noticeable improvement in overall imaging and sound stage at the end of this step.

Step 4: Get the timing right

Although there is improvement after dialling in the crossover and balancing levels, it’s crucial for users of multiple speakers and subs to ensure that their setup is synchronised and cohesive. This is where timing comes into play.

To ensure that the speaker system is in sync, you can tighten the audio timing through the delay or time alignment setting, which can be found on your receiver. All you need to do is input the distance between you and each speaker and the sub. Some receivers even factor in different seating positions to average out these measurements, making the adjustments easier.

While the impact of time alignment is not as apparent as crossover and speaker level adjustments, it can affect the timbre of some musical notes and instruments.

Step 5: Use EQ to add the finishing touch

 

Now that your sound system is properly calibrated, it’s time to start the fine-tuning process. There are two different schools of thought for the finishing touches: purists believe in getting the flattest frequency response for a truly neutral-sounding system, while realists believe in boosting both ends of the sound spectrum to offset our hearing deficiency of picking up extreme lows and highs.

Regardless of the approach, you will now have to connect your smartphone to the auxiliary input of your receiver. This will allow you to play test tracks and accurately measure the overall frequency response of your sound system.

The initial frequency response curve is likely to be anything but smooth with dips and peaks, so your immediate task is to rectify these anomalies by using the EQ to compensate accordingly. For example, you can progressively increase the gain for the 125Hz band if there is a substantial dip around that region.

While the goal is to smoothen out the curve, you should also avoid extreme adjustment to avoid distortion. At this point, you can try using the realist approach to artificially boost the sub-200Hz and above 12K range to create a V shape-like response curve.

More trial and error

Congratulations! You’ve just completed calibrating your speakers and sound system. However, this is just the beginning of your journey to better sound – it will take additional fine-tuning to customise the sound quality to your liking.

Keep in mind too that each set of speakers is tuned differently. For example, the flagship Pioneer Z- and D-series speakers are tuned for greater clarity and extension, whereas the G-series speakers are designed to be more general all-rounders. It is impossible to calibrate the G-series to replicate the performance of the Z-series.

But if all these tweaks are too technical for you, higher-end Pioneer receivers also feature auto-calibration functions – all you need to do is to purchase and attach a microphone to get started.