There are two reasons why we’d want to upgrade the speakers in our vehicle: the original speakers may be damaged, or we want to improve the clarity of the audio system. In either case, you’re going to need to visit a local mobile enhancement retailer and choose a speaker solution that fits your vehicle, works with your budget and sounds great. This will involve auditioning several options before you make a purchase. Not listening to speakers before buying them would be like trying to pick out a suit or choose a new paint color for your car while blindfolded.

Choose the Right Music

The first step in auditioning speakers is to choose the right music. You’ll want to pick something that you know well and have listened to on a variety of audio systems. You should listen to these songs, or portions of them, as much as you can before you go shopping.

It’s best to choose tracks that highlight certain aspects of a speaker’s performance. For example, a song with a solo vocalist is a good way to evaluate midrange tonal balance. Smooth response through the midrange is crucial as our hearing is very sensitive to these frequencies. Even subtle changes in midrange response are easy to detect.

You will want a track that demonstrates the overall tonal balance of the speaker. If we are looking at a coaxial or component speaker, then choosing a solution with energy from the midbass, midrange and high-frequency range is essential.

Where a great speaker separates itself from the mediocre is in its dynamic performance. There’s no such thing as a fast speaker. The ability of a speaker to respond to a transient signal is determined by its frequency response. What you want to evaluate is how fast the speaker settles after the signal is removed. Tracks with percussion, bass guitar or an upright bass are great for this. Does the speaker respond to a floor tom with a snap, or is it sloppy with lots of resonance? Does the pluck or strum of a string resonate clearly, or does it get shrouded in harmonic content?

Control All the Variables

When you go speaker shopping for your car, truck, motorcycle or boat, it’s likely that you’ll be listening to a display in a store. You’ll want to try to listen to music at the same volume level on every speaker you audition. Increasing the volume, even by a small amount, will make background sounds seem louder and more present. Higher volumes can also excite resonances in the room that will make it seem like a speaker is producing more bass.

Where the challenge of matching the output of one speaker to another gets exasperating is that it’s rare to find two different speakers with the same efficiency. Try as hard as possible to make things equal.

You’ll want to make sure there isn’t any equalization applied to the speaker. The tone controls on the source unit should be set flat. Some higher-end displays may include a digital signal processor. In these cases, ask whether each speaker solution has been matched to the same reference frequency response curve and target efficiency. If so, this is an ideal way to compare the performance of different speakers.

Consider System Design

If your car audio system will include a subwoofer, then how you audition a set of coaxial or component speakers will change. You should ask that a high-pass filter be applied to the speaker so that it’s not trying to make bass. In fact, you’ll find that speakers that seem to produce a little less midbass are often more accurate than ones that produce more.

Loudness or emphasis within a narrow band of frequencies is not an indication of quality. It’s usually a sign of unwanted distortion or poor design. Check out our article on Speaker Q for more information on this topic.

If you’ll be using the speakers without a subwoofer, then bass output matters. You may choose to trade some accuracy in the midbass region for more output. It’s a worthy sacrifice to make the system enjoyable.

What Will the Speakers Sound Like in My Car?

The problem with auditioning speakers in a showroom is that unless they have been equalized with a DSP to a specific target curve, you’ll hear something different once they are installed in the car. What you’re looking for isn’t the absolute response of the speaker, but the performance characteristics of the driver and how they differ from the other options. Your job is to pick out the speaker that sounds as accurate as possible. A speaker that is bright on the display may be annoyingly harsh in a vehicle. Likewise, one that produces a lot of midbass may sound very boomy or sloppy. If the speaker is neutral and accurate, then it’s likely to be a well-designed solution that will sound great.

Listen, Listen and Listen

When it’s time to shop for new speakers, audition as many options as is reasonable. Learn to pick out the performance differences between the options. You can start this process at home with a home stereo, a portable Bluetooth speaker and your smartphone and some headphones. Very quickly, you’ll be able to pick out a speaker that sounds right. Once it’s in your vehicle, you can have the technician tune the system to deliver the frequency response you enjoy.

Put a few songs you know well on a USB memory stick and head to your local specialty mobile enhancement retailer today. Auditioning new speakers can be a lot of fun and very educational. Done correctly, it ensures that your audio system will sound the best it can.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

When it comes to upgrading a car audio system with a digital signal processor, you’ll typically hear about a discussion of signal delay. Maybe people refer to this as time alignment or setting the delays. No matter what term is used, understanding the benefits and drawbacks of this technology is crucial to creating a car audio system that sounds amazing.

Let’s Talk About Stereo

Three crucial factors are required to recreate a coherent and accurate stereo imaging from a sound system. First, the frequency response of the left and right speakers needs to be the same. If there are differences, sounds that are louder in one channel will appear to move toward that corresponding speaker. Second, and this is an extension of the first, the volume level of both speakers needs to be the same. Finally, and most relevant to our discussion of delay, the sound from each speaker needs to arrive at the listening position simultaneously.

In a home audio system, we can move our chair or change seats on the couch to place ourselves in a position that’s equidistant from each speaker. If the speakers are similar distances to the rear and side walls, then their frequency response should be similar. The result is a listening experience where sounds appear to emanate from the space between those speakers. We call the plane from which the sounds come from the soundstage. The accuracy with which each performer and instrument are rendered on the soundstage is described as imaging. Better imaging means that each voice or instrument is rendered with more precision and detail, making the sounds seem more realistic. If a recording captured the reflections in the room, then an audio system with good staging and imaging can reproduce those sounds and provide a sense of space.

What Is Signal Delay?

If we are sitting between two speakers, then the distances to each speaker are equal. The problem is, we are talking about car audio systems. When we’re driving, we sit on the left side of the vehicle, which puts us much closer to the left-side speakers. This results in those speakers seeming louder than the right-side drivers and, crucial to this discussion, we hear sounds from the left speakers before those coming from the right.

In terms of our soundstage, when the perceived output level of the speakers is different, and we hear one speaker long before the other, the soundstage will be compressed into the very left side of the vehicle. This doesn’t sound very realistic.

Even modestly priced car audio DSPs and many premium radios have the ability to add delay to the output of one or more channels. Through various configuration and calibration methods, these adjustments add delay to the signals going to speakers in your audio system. Let’s say you have a simple three-way system with tweeters in the sail panels, woofers in the doors, and a subwoofer in the trunk. You will hear the left tweeter before any other speaker because it’s the one closest to you. Next, you’ll hear the left woofer. This is followed by the right tweeter, then the right woofer, and finally, the subwoofer. Uncalibrated, you end up with a blurry, unfocused mess. When the technician calibrating your processors adds delays to all the speakers, the sound from each arrives at the listening position simultaneously.

Speaker Delay Settings

Getting the delay settings correct is not only important to make it seem as though we are sitting exactly between the speakers, but it also affects the frequency response of the audio system. If there are effective pathlength differences between the left and right speakers, some sounds will add constructively, and some will add destructively. This frequency response issue is called comb filtering, and it’s nearly impossible to EQ out of a system.

Inexpensive to moderately priced processors usually have delay adjustments with a resolution of 0.02 milliseconds. That means each step is about 6.8 millimeters or about 0.27 of an inch. Newer processors that use higher sampling rates of 96 kHz can cut those numbers in half. Don’t get hung up on the resolution of the delay setting when purchasing a DSP – it’s more important to set them all properly than to have a little extra resolution.

Let’s Talk About Two-Seat Systems

As you can imagine, setting the delays to each speaker in our hypothetical three-way system will, when combined with proper speaker placement and equalization, result in an audio system that sounds amazing. That great sound, however, is only heard in one seat – the driver’s seat. Your passenger will hear almost all of the music coming from the right edge of the vehicle. We call this a one-seat tune.

Audio systems designed to deliver balanced sound from all positions in the vehicle require a different approach. Your installer will need to implement all-pass filters to tame the comb filtering. Ideally, the vehicle should use a processor with an upmixer that extracts mono information from the left and right channels and feeds it to a dedicated center speaker. To my knowledge, there’s only one DSP currently on the market with this type of upmixer.

Upgrade your Car Audio System with a Digital Signal Processor

Without a DSP, your technician can use an equalizer or level controls to try to balance the perceived output of the speakers in your vehicle. While this helps create a center image, the focus will be mediocre, and the sounds that are left and right of center will be compressed, stretched and likely blurry. When you add a DSP with a stereo equalizer and signal delay capabilities, then have the system calibrated by a trained professional, your music will sound like you are sitting in your living with natural balance and fantastic realism. Drop by your local specialty mobile enhancement retailer today to audition a digital signal processor and have them upgrade your car audio system.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

As we roll forward with our look at the importance of digital signal processors in car audio systems, we’ll talk about the need for proper equalization. Even if you’ve purchased the best speakers available and invested in having them integrated into your vehicle with the utmost precision – compensating for the acoustic characteristics of the vehicle is necessary to achieve great sound quality. Let’s look at how the equalizer in a digital signal processor works, explain its importance, and offer some purchasing tips.

What Is an Equalizer?

An equalizer, often called an EQ as an abbreviation, is an electronic device that changes the frequency response of an audio signal. The simplest and most common equalizer would be the bass and treble tone controls built into a standard radio.

In the digital domain, there are four types of equalizers that we’ll discuss: graphic, parametric, semi-parametric and shelving.

Graphic Equalizer Basics

A graphic equalizer comprises a number of adjustments (called bands) that are set at specific frequencies. The range of frequencies each band affects is determined by the total number of frequencies in the equalizer. A 31-band EQ is often referred to as a 1/3-octave equalizer because there are three adjustments available per octave. For a 31-band equalizer covering the entire audio range from 20 Hz to 20 kHz, each adjustment has a Q of roughly 4.32. If you have a 20-band EQ, then that would be a half-octave EQ, and each adjustment would have a fixed Q-factor of 2.87.

Each band of the equalizer can add to the signal (called boosting) or remove information around a specific frequency (called cutting). There are myths around the maximum amount of boost you can add to a signal that was based on analog processing and noise issues. Properly designed 32-bit processors have enough digital headroom that significant boosts don’t cause distortion. It should be noted that if there is a need for a significant amount of boost, there’s possibly a cancellation issue in the vehicle that can’t, or shouldn’t, be resolved with tuning.

Parametric Equalizer Basics

A parametric equalizer is more flexible than a graphic EQ in that you have control over the center frequency and the bandwidth of each equalization band. As such, each band has three values associated with it in the configuration screen. This flexibility allows the technician who is calibrating the system to hone in on specific issues. Since the concept often isn’t understood, we’ll provide a couple of examples to demonstrate how adjusting the Q-factor changes the range of frequencies that each band alters.

Semi-Parametric Equalizer Functionality

Though rare in the car audio industry, a semi-parametric equalizer (sometimes called a paragraphic EQ) allows you to pick a center frequency for each band, but you can’t adjust the Q-factor. For example, most 1/3-octave EQs have bands centered at 800, 1,000 and 1,250 Hz. A semi-parametric EQ will let you pick any frequency. In the example below, we have a 1/3-octave EQ with a fixed Q-factor of 4.31. The center frequency of the band is set to 1080 Hz and the boost remains at 10 dB.

Shelving Equalizer Applications

Very few digital signal processors include shelving equalizers. With that said, they can be handy in terms of shaping the acoustic response of a mobile audio system to suit the listening preferences of the vehicle owner. A shelf EQ boosts or cuts frequencies above or below an adjustable frequency. If the technician needs to tame a set of efficient tweeters in a passive system, shelving equalization is a great way to make that adjustment and maintain a smooth transition to adjacent frequency bands.

All-Pass Filters in Two-Seat Systems

If you are having an audio system designed and installed such that it will be configured to provide a stable relatively center image from both the driver and passenger seat, then you will need a signal processor that includes the capability of adding an all-pass filter. An AP filter doesn’t affect the frequency response of the signal, but it improves the way the left and right channels interact with each other.

Why Does Your Car Audio System Need a DSP Equalizer?

As we mentioned at the beginning of this article, equalizing the output of your speakers to compensate for changes in frequency response because of reflections and resonances is crucial to obtaining great sound in your car or truck. As the sound produced by your speakers reflects off of different surfaces in your vehicle, it will be reflected toward the listening position. The variances in arrival time wreak havoc with the perceived frequency response of the system.

The graph above shows the frequency response of a four-way audio system. The green trace highlights just how bad this system would sound. There’s more than 12 dB of variation between 220 Hz and 700 Hz, and another dip of 11 dB at 2.8 kHz. There’s also no bass and too much high-frequency energy. The violet curve shows how some equalization can smooth the response of the system. After calibration, the system is flat within 4 dB from 200 Hz to over 15 kHz. The boost in the bass and the roll-off of the high-frequency information demonstrate that the system was calibrated to a commonly-used, quite enjoyable reference (or target) curve.

Shopping for the Right DSP Equalizer

When it comes time to buy a digital signal processor for your car audio system, you’ll want to ask your product specialist a few questions. If you’re investing in a processor, then you likely have an audio system designed to use active filtering. You will want to ask about how many EQ bands are available for each output. If it’s a graphic EQ and you have an active system, 15 bands per output, assuming they are at least semi-parametric, is adequate. If the system is going to use passive filters between a midrange and tweeter, you may want more bands – 30 would be ideal. These numbers drop dramatically if the system uses parametric filters – 10 is likely adequate for a properly designed system.

Global DSP equalization is important to maintaining correct phase through the crossover region. The DSP you choose should offer the ability to adjust multiple bands simultaneously.

Presets are another great feature. You may want to have one configuration that’s tuned close to a reference system response curve for critical listening and have another with a little more bass and midbass for those times when you want to rock out at high volume levels.

Experience How a Digital Signal Processor Can Improve Your Car Audio System

Even if you have a simple car audio system with a four-channel amplifier and new front and rear speakers, a digital signal processor can, once calibrated for your vehicle, transform the listening experience into something that’s truly remarkable. Drop by your local specialty mobile enhancement retailer today and ask for a demonstration. You’ll be blown away!
This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.