In the fall of 1982, Billy Joel’s 52nd Street was among the first 50 albums released as consumer-available compact discs. It had been only about four years since digital recording equipment was introduced to studios. This marked a revolutionary change in how consumers would buy their music. It was the dawn of an all-digital era, where performers could have their music captured with impressive accuracy and minimal background noise for delivery to consumers. Since then, not much has changed in the way we digitally capture and store analog waveforms. We just have a few more bits of depth to improve noise performance and higher sampling rates to ensure that bats and mice can hear that extra octave.

On the reproduction side of things, dozens of companies have made claims about increases in performance because of these higher sampling rates and increased bit depth. Unfortunately, the marketing guys haven’t been talking to the engineers to understand how the process works. This article will look at the digital stairstep analogy and explain why it’s misleading.

How Is Analog Audio Sampled?

Digital audio sampling is a relatively simple process. An analog-to-digital converter (ADC) measures the voltage of a waveform at a specific rate and outputs digital information that represents those amplitudes. The sampling rate defines the number of samples per second, determining the Nyquist frequency. The Nyquist frequency is the highest frequency the ADC can record accurately and is half the sample rate. For a compact disc with a sampling rate of 44.1 kHz, the highest frequency is 22.05 kHz. This frequency is beyond what most humans can hear, so it’s more than high enough to capture any audio signal we’d need to reproduce.

Bit depth describes the number of discrete amplitudes captured in a sampling process. If you have read audio brochures or looked at websites, you’ve undoubtedly seen a drawing showing several cubes intended to represent samples of an analog waveform. These diagrams are often referred to as stairstep drawings.

The size of the blocks on the horizontal scale represents the sampling rate, and the size on the vertical scale is the bit depth. We have 20 levels in this simulation, equating just over 4.3 bits of resolution. It’s not difficult to see that this would introduce some amount of error and unwanted noise. However, even the earliest digital samplers, like the Fairlight CMI, had only 8 bits of depth, equating 256 possible amplitudes. Later versions increased the bit depth to 16, dramatically improving sample accuracy.

Once we have enough bit depth, we can accurately reproduce the waveform without adding unwanted noise. For example, the orange data in the image below has lots of bit depth, and the difference between the orange and blue would be perceived as noise in the recording.

What about those steps? Isn’t music supposed to be a smooth analog waveform and not a bunch of steps? Companies that purport to offer support for higher resolution audio files or those with more bit depth will often put a second image beside the first with smaller blocks. The intention is to describe their device as being more accurate.

The problem is, the digital-to-analog converter doesn’t reproduce blocks. Instead, it defines an amplitude at a specific time point. A better representation of how analog waveforms are stored would be with each amplitude represented by an infinitely thin vertical line.

A better way to describe the function of a DAC is to state that each sample has a specific voltage at a particular point in time. The DAC has a low-pass filter on its output that ensures that the waveform flows smoothly to the next sample level. There are no steps or notches, ever.

Digital Bit Depth Experiment

Rather than ramble on about theory, let’s fire up Adobe Audition and do a real-world experiment to show the difference between 16- and 24-bit recordings. We’ll use the standard compact disc sampling rate of 44.1 kHz and a 1-kHz tone. I created a 24-bit track first and saved it to my computer. I then saved that file again with a bit depth of 16 bits to ensure that the timing between the two would be perfect.

Here’s what the waveform looks like. The little dots are the samples.

Now, I’ll load both files and subtract the 16-bit waveform from the 24-bit. The difference will show us the error caused by the difference in bit depth.

At a glance, it appears the difference is invisible. Maybe it’s hard to see the difference between the two files. Let’s look at some data in a different format. Here’s the spectral response graph of the difference.

As you can see, the difference is noise at a level of -130 dB. This amplitude is WAY below the limits of any audio equipment and, as such, is inaudible.

Let’s make the comparison more dramatic, shall we? I’ve saved the 16-bit track again with a depth of 8 bits.

This time, we got a result. You can see some waviness in the difference. This makes sense, as an 8-bit file only has 256 possible amplitude levels, and a 1-volt waveform has a possible error of almost 2 millivolts. Let’s look at this in the spectral domain.

Now we have something audible. Not only can we see the 1-kHz waveform in the difference file at an amplitude of -70 dB, but we can see harmonics of that frequency at 1-kHz spacings to the upper limits of the file.

High-Resolution Audio Sounds Better

What have we learned about digital audio storage? First, each sample is infinitely small in the time domain and represents a level rather than a block. Second, there is no audible difference between a 16-bit and a 24-bit audio file. Third, 8 bits aren’t enough to accurately capture an analog waveform. What’s our takeaway? If we see marketing material that contends that a recording format with more than 16 bits of depth dramatically improves audio quality, we know it’s hogwash.

Wait, what about hi-res audio? Doesn’t it sound better than conventional CD quality? The answer is often yes. The reason isn’t mathematical, though. Sampling rates above the CD standard of 44.1 kHz can capture more harmonic information. Is this audible? Unlikely. Does having more than 16 bits of depth help? We’ve proven it doesn’t. So, why do hi-res recordings often sound better than older CD-quality recordings? The equipment used in the studio to convert the analog waveform from a microphone is likely decades newer and adds less distortion to the signal. If the recording is genuinely intended to be high-resolution, the quality of the microphone itself is better. Those are HUGE in terms of quality and accuracy.

A second benefit of higher bit-depth audio files is less background noise. When multiple sound samples are combined in software like Pro Tools, the chances of the background noise combining to become an issue are dramatically reduced.

The next time you shop for a car radio, consider a unit that supports playback of hi-res audio files. They sound better and will improve your listening experience. A local specialty mobile enhancement retailer can help you pick a radio that suits your needs and is easy to use.

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.

Speakers are, by a long way, the most influential component in any audio system when defining performance or quality. Low-quality speakers, or those without specific technologies, can’t match the clarity levels of premium solutions. In addition, many music enthusiasts want their car audio systems to play louder than what’s possible with factory-installed equipment. After all, jamming to your favorite music while going to work or school is a great way to start the day! Is upgrading the speakers the right solution? Let’s look at the physics of loudspeaker efficiency and output capability.

Car Audio Speaker Efficiency

One of the many reasons people ask to upgrade the speakers in their cars and trucks is a desire for the system to play louder. Unfortunately, most high-performance speakers aren’t as efficient as those that the manufacturer provided.

When shopping for speakers, you’ll need to look at the efficiency specification. This number describes the amount of sound a speaker will produce for a given signal from an amplifier. The standard specification describes the speaker’s output in dB SPL at 1 meter from the speaker when powered with 1 watt from an amplifier.

A second standard exists where 2.83 volts are applied to the speaker, and the output is measured at 1 meter. There is nothing wrong with the 2.83-volt rating, except that you have to consider the speaker’s impedance when comparing drivers. For example, a drive level of 2.83 volts equals 1 watt of power when driving an 8-ohm speaker, 2 watts when driving a 4-ohm speaker and 4 watts with a 2-ohm speaker.

The output of a speaker increases or decreases by 3 dB every time the power is doubled or halved. Therefore, be sure you’re comparing like numbers when comparing speaker efficiencies. If no drive level specification is provided, it’s safe to assume the manufacturer will choose the 2.83-volt measurement to produce the highest numbers.

Are New Car Audio Speakers Going To Be Louder?

A while back, we measured the output of a 6.5-inch speaker from a Honda Civic as part of our series on understanding speaker quality. Our measurements showed that this speaker had an efficiency of 89.04 dB SPL when driven with 1 watt of power and measured at a distance of 1 meter. So how does this number compare to common replacement speakers? First, let’s look at a few examples from Rockford Fosgate. I’ve chosen this brand as it has a variety of offerings and many price points and performance levels.

Starting with its most affordable option, the Prime Series R165X3 has a rated efficiency of 91 dB SPL at 1W/1M. You’d be able to hear this 2-dB increase in output. What if you want a better speaker? It seems logical to move up to one of the Punch Series drivers. The P1650 is a very popular replacement speaker, but it has an efficiency of 88 dB SPL at 1W/1M. Does this mean the speaker isn’t as good? No, it’s simply not as efficient. If you want an even better speaker, then the Power Series T1650 is the next step in the series. This driver also has an efficiency of 88 dB SPL at 1W/1M. So why are the better speakers not louder?

When a transducer engineer is designing speakers, they must balance many characteristics. How efficient will the driver be? How low should it play? How much power can it handle? How much excursion is required? Unfortunately, some of these characteristics oppose each other. A driver of a given size that is intended to play lower frequencies will need a lower resonant frequency. This lower Fs value is usually achieved by increasing the cone’s mass and softening the suspension. The increased mass of the cone assembly decreases the driver’s efficiency. An extreme example of this would be a 6.5-inch subwoofer. A typical 6.5-inch car audio subwoofer has an efficiency of around 80 to 81 dB at 1W/1M.

As you can see, the 6.5-inch midrange driver is much louder at higher frequencies. So, why not use it as a subwoofer? Well, it doesn’t have the power handling or excursion capabilities required to reproduce low-frequency audio and high volume levels. A typical full-range 6.5-inch driver might handle about 50 or 60 watts of power and have a maximum linear cone excursion of roughly 3 millimeters in each direction. An equivalently sized subwoofer might handle 150 watts of power and have 9 to 10 millimeters of excursion capability. Since we know that speakers need to move a lot more air to produce bass, it’s clear that the subwoofer would be louder at lower frequencies.

What About PA Speakers?

We have pro audio or PA speakers at the other end of the speaker spectrum. These drivers are designed for applications where the most output possible is required from minimal amounts of power. For example, let’s say you were responsible for setting up the sound system for a Metallica concert in an open-roof stadium. Many of these installations have about a megawatt of power driving the speakers and subwoofers. Assuming 220-volt, 30-amp circuits feed the amplifiers, the sound system would need more than 180 circuits. However, if you could find 3 dB more efficient speakers, you could get the same output for the audience from 90 circuits and half the amplifier power.

PA speakers use designs that trade low-frequency output for increased midrange output. For example, a 6.5-inch PA-style speaker might have an efficiency of 92 or 93 dB at 1W/1M. This would be achieved by lowering the mass of the cone assembly as much as possible. The trade-off would be output at lower frequencies. Unfortunately, many high-efficiency 6.5-inch speakers have an Xmax specification of only 1.5 to 2 millimeters. As a result, they sound horrific when used incorrectly and driven with midbass information in the 80-to-150-hertz range at high levels.

Unlike a car audio system, there’s no need to drive concert midrange drivers down to 80 Hz to help with the perception of bass frequencies sounding as if they’re coming from the front of the vehicle. Instead, the crossover point can be at 150 or 200 hertz, and the system will sound the same to the audience. If you look at the frequency response specification of a concert subwoofer, you’ll find that most are designed to play up to 200 hertz. You may also note that these subwoofers also call for a high-pass filter, or what car audio enthusiasts would call an infrasonic filter at 35 hertz.

As you can see from the graph above, the green trace shows that the speaker is much more efficient in the upper midrange, but at the expense of low-frequency output.

Which Speakers Are Right for My Car Audio System?

In general terms, you have two options for replacement speakers for your car stereo: You can choose from a number of relatively high-efficiency solutions like the X2 speakers from ARC Audio, Prime Speakers from Rockford Fosgate, Prima speakers from Audison or Uno speakers from Hertz. These are great choices if you use a radio with up to about 22 watts of power to drive them.

If you plan on adding an amplifier to your car audio system, your speaker choice might change to something like the ARC Audio ARC Series, the Rockford Fosgate Punch, Sony Mobile ES or Hertz Cento. These speakers can handle more power and have more excursion capability to play louder. With that said, they need more power to reach those output levels. A secondary reward for choosing better speakers is that they are typically clearer and more detailed.

When it’s time to upgrade your car stereo, visit a local specialty mobile enhancement retailer so you can audition the speakers they have on display. Talk to the product specialist about your long-term plans for your audio system, along with your immediate performance improvement goals. They can use this information to select speakers that will meet your expectations.

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.

Adding an amplifier to your car stereo is a great way to improve its performance. If the amp is going to power speakers, you should be able to listen to your music at higher volume levels without worrying about clipping distortion. Of course, we all know that one of the best upgrades you can make to any car audio system is to add a subwoofer and a dedicated amplifier to drive it. Your installer will need a line output converter interface when connecting that amplifier to a factory-installed radio. Should you use a stand-alone unit, or is the converter built into a high-quality amplifier adequate?

What Does a Line Output Converter Do?

The audio signal from most car radios is designed to drive a speaker. There are two connections for each speaker, a positive and a negative. There are signals on both of these wires that we call a bridge-tied load configuration. Unfortunately, many low-quality amplifiers with single-ended input circuitry won’t work with this signal configuration and could damage the radio.

Most amplifiers are designed to produce their maximum output with signals ranging from a few hundred millivolts to 4 or 5 volts. The sensitivity or gain control on the amplifier adjusts how much signal it produces so it can work with various voltages. Bad things will happen if the radio produces more voltage than the amp input stage can handle.

To summarize, a line output converter reduces the radio signal to something the amp can handle. It also converts the signal from a bridge-tied load to a single-ended configuration that will work with any amplifier, even those low-quality units that don’t have differential or balanced inputs.

What Makes One LOC Better Than Another?

If you read our comparison of line output converters, you know that some do a good job of converting the signal from the radio and some add a lot of distortion while negatively affecting frequency response. Therefore, based on our research and testing, you’ll want to avoid transformer-based converters.

Beyond that, why would a person choose an external converter from ARC Audio, Wavtech or AudioControl over a converter built into an amplifier? There are two reasons.

The first reason you might need to use an external line output converter is to deal with high voltages. If you have an amplifier connected to the output of a high-power factory-installed amplifier, there may be as much as 40 volts on the speaker wires to contend with. Almost no analog-only amplifier can handle this much voltage. Your installer will need an audio frequency analyzer and an oscilloscope to determine the maximum voltage of the signal coming out of the factory-installed audio system.

Amplifier Activation Circuitry

Another reason you might need an external line output converter is if your chosen amplifier doesn’t have automatic turn-on circuitry. When an aftermarket amplifier is connected to an aftermarket source unit, a control wire on the radio tells the amp when to turn it on and off. Unfortunately, in 99% of upgrades that use a factory-installed radio, there is no wire available to tell the amp what to do.

Many high-quality line output converters include remote turn-on circuitry. These converters have a wire that can be connected to the remote turn-on terminal on your amp to activate it when you turn on the radio or start playing music.

Are Built-In Line Output Converters Good?

The last consideration in our discussion about line output converters is their performance. Is there a performance benefit to be had by using a premium external converter instead of one built into an amplifier? The answer depends on a few variables. If the LOC is connected to a simple radio with a built-in 18- to 20-watts-per-channel amplifier, using the converter built into an amplifier will be just fine. There are other considerations if the factory-installed audio system uses a Class D amplifier. Class D amplifiers MUST have a low-impedance load connected to their outputs to function correctly. You may have heard of load resistors or similar in discussions about connecting to a factory-installed audio system.

If your vehicle comes with a Class D amplifier, it needs something like the AudioControl LGD wired to the speaker terminals. Which of the AC-LGD devices your vehicle needs depends on the amp design. Your installer will know which they should use. Once these are in place, you can use the LOC built into an amplifier. An alternative is to use a LOC that has load-generating resistors built in. The Wavtech and AudioControl solutions include this feature.

When it’s time to upgrade the factory-installed stereo in your vehicle, drop by a local specialty mobile enhancement retailer. They can suggest the best products to deliver the sound you want and will install them to maximize their performance. For example, if they suggest an amplifier with a built-in line output converter, it could save you some money.

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.

Though it only seems like last year, our 2019 article about the importance of test-driving a new car radio before buying is suddenly more important than ever. So let’s review some key factors and discuss a few new things you ought to test before purchasing a new radio for your car or truck.

Test the Interface

One of the most important reasons to try out a new car radio, especially a multimedia receiver, is to evaluate the responsiveness and simplicity of the interface. For example, years ago, I had a top-of-the-line navigation-equipped multimedia receiver in my Jeep Grand Cherokee SRT-8. The radio sounded amazing and had every feature imaginable at the time. Unfortunately, to make the radio as “cool” as possible, the manufacturer included a capacitive touch interface across the bottom of the screen. Whenever I went to adjust the subwoofer level from the on-screen menu, my fingers would accidentally touch this panel and bring up the radio’s configuration menu. It was very frustrating to use.

When shopping for a radio, you want to try to use it as you would in a vehicle. Is the volume easily accessible without looking at the radio? Can you change songs easily? Can you change sources easily? How quickly does the interface respond to your inputs? You would be surprised at how slowly some radios respond to inputs. You want the radio to act like a smartphone. It’s impossible to gauge responsiveness by looking at a picture or watching a video.

Will It Play My Music?

Another critical test is to confirm that the radio will play your music. We aren’t talking about rock versus country and heavy metal. Do you have a digital audio collection stored in a format other than MP3? If so, you’ll want to connect your USB memory stick to the radio you have in mind to see whether it will recognize your music collection. You’ll want to ensure that it can detect all the tracks on the memory stick, checking to make sure that software restrictions aren’t hiding some files. Check both the root and subfolders to see that all the tracks are listed and in the order you expect.

You’ll also want to know if the radio remembers the song playing when the ignition is turned off, then back on. In the same scenario, does it restart at the song’s beginning or continue where it left off? If you listen to concerts or something like an audiobook, this matters. Check to see whether the radio adds a pause between tracks. Pauses between tracks make listening to concert albums annoying. Also, test to see how long it takes for the radio to play music after you turn it on.

Will the Radio Work Correctly with My Vehicle?

You’ll want to ask the retailer how the radio will function with your vehicle. Will the illumination dimmer work? Will a factory-installed backup camera display properly? Can the radio buttons on the steering wheel work with the aftermarket receiver? Find out how the steering wheel’s up and down tracking buttons work when listening to the radio. Do they take you to the next radio station preset or seek the next frequency the radio can lock on to?

Smartphone Integration

Here’s the topic that was the inspiration for this article. If you plan to use Apple CarPlay or Android Auto, you must check that your phone and the software it’s running will work with the radio. More importantly, if you plan to use wireless CarPlay or Android Auto, you must test that functionality. Three popular Android-based smartphone brands don’t work with wireless Android Auto on some multimedia receivers. Based on some cursory research, the issue appears to be a hardware limitation, so hoping that a software update will resolve things isn’t likely.

Have Realistic Expectations That Manufacturers Can Help

If you’ve purchased a radio that doesn’t work with your device or how you want, you can ask the manufacturer if they’re working on an update to address the issue. That said, please don’t assume they can or will be able to fix any problems. The software in a multimedia receiver is complicated; changing one part can dramatically affect the other functions in a radio.

Testing an update can take weeks or months to ensure that one change doesn’t break anything else. High-quality radio manufacturers like Sony, Kenwood, Pioneer, JVC and Alpine have teams dedicated to testing multimedia receiver software. If they’re working on an update to an existing product, that often delays the delivery of new models for the following years. Updates that might affect the operation of a technology like Apple CarPlay must go to Apple for approval. That process can take half a year. Trust us; we’ve been through it.

We can’t say it enough: Before purchasing, you MUST test the radio you want to buy on a display board. When it’s time to upgrade the technology in your vehicle, drop into a local specialty mobile enhancement retailer and talk with one of their product specialists. Bring your smartphone and some digital audio files along to test that the radio they suggest will function the way you want once it’s installed in your vehicle.

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.

Unlike a home audio system, you can listen to your car audio system as loudly as you want while driving to work or school. Sure, the folks beside you at a stoplight might laugh as bit as you’re rocking out to “Bohemian Rhapsody,” but that’s their problem, not yours! If you want your music to sound good at high volumes, you’ll likely need to upgrade your car stereo system with an amplifier. Let’s look at three reasons music enthusiasts need an amplifier added to their car stereo system.

Laying the Foundation

To be clear, even the most basic car radio, installed by the factory or at a mobile enhancement retailer, has an amplifier built in. In most cases, these amplifiers are a single integrated circuit that can deliver between 15 and 20 watts of continuous power to four speakers. Sony High Power radios are the exception to this. These High Power radios use an amplifier that can deliver an actual continuous 45 watts of power to each of the four speakers.

When we talk about adding an amplifier to an audio system, we’re talking about a stand-alone solution that would mount under a seat or in a vehicle’s trunk or storage area.

One last note before we dive into the reasons to upgrade your car’s audio system with an amplifier. When looking at amplifier ratings, we only discuss continuous ratings and never peak or dynamic power. If you want to understand how amplifier power (and other specifications) should be measured, please refer to the BestCarAudio.com article about the recently-updated ANSI/CTA-2006-D Testing and Measurement Methods for In-Vehicle Audio Amplifiers standard.

Amp Upgrade Reason 1: More Output

Let’s assume that you have a basic factory-installed radio in your vehicle that can provide about 20 watts of power to each speaker. Assuming the speakers are about 89 dB (1-W/1-M) efficient like the Honda speaker we tested, we can surmise that 20 watts of power would let each speaker produce about 102 SPL dB of output. With four playing in the car, 112 dB SPL is theoretically possible before the amplifier hits its power limit and starts clipping and adding distortion. Clipping will make the music sound very garbled and muddy.

If we upgrade the system to an amplifier that provides 75 watts of power to each speaker, the maximum output would be almost 108 dB SPL per speaker. The four could theoretically produce 120 dB of output. Unfortunately, the speakers that came with your car likely can’t handle this much power or play that loudly. Nevertheless, your stereo system will play louder and clearer with an amplifier than just running off the little IC amp built into the radio.

Amp Upgrade Reason 2: More Bass

You likely know that it takes a lot more power for speakers to reproduce bass frequencies than it does to produce midrange and high-frequency information. In fact, for a constant output level, speakers need twice as much power for every octave lower you want the system to play. By way of an example, if a speaker required 10 watts of power to play 200 hertz at 100 dB SPL, it would require 20 watts of power to play 100 hertz at the same volume level. If we extend this further, we need 40 watts to play 50 Hz and 80 watts to play 25 Hz. It’s easy to see that we run out of power quickly as the audio information we want to play loudly contains more bass information.

One of the most significant benefits of having a more powerful amplifier is the ability of the audio system to reproduce the low-frequency information in the music you’ve chosen without distorting it. Think about what adding a dedicated subwoofer and amplifier does. The small speakers in your car can focus on playing audio information above 80 Hz, and the subwoofer and its amplifier can handle the heavy lifting for frequencies below that. Even if you use a radio to power the smaller speakers, they can play louder because they don’t need to try playing bass frequencies. This is why adding a subwoofer to your car audio system is one of the best upgrades you can make.

Amp Upgrade Reason 3: Improved Performance

Another great reason to upgrade your car’s audio system with an amplifier is to improve performance. The little IC amplifiers are impressive in their capabilities, but they can’t hold a candle to a premium amplifier in terms of distortion characteristics. These IC amps’ distortion versus output power characteristics are reasonable around 1 kHz but fall short of what would be considered good at frequencies outside that range. Conversely, a well-designed amplifier adds several orders of magnitude less distortion. Likewise, the channel separation will improve, and the system will add less noise. Of course, the accuracy of this statement depends wholly on the amplifier you choose. If you pick one of those internet brands, you’ll likely be relegated to the system just playing louder and not being any clearer.

Improve Your Car Audio System with an Amplifier Upgrade

If you want your car audio system to play louder, produce more bass and sound more precise, visit a local specialty mobile enhancement retailer today and ask about adding an amplifier. They can help you choose a model that will sound great, have enough channels to drive the speakers you want and include features that will improve the system’s performance. Best of all, they can install and configure the amp to provide the best possible performance.

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.