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Five Essential Car Audio Maintenance Tips

Car Audio Maintenance

Unlike home audio systems, car stereo upgrades have to withstand harsh conditions. Your car, truck or SUV subjects your system to vibration, bumps and massive temperature changes. At home, as long as there isn’t a flood, everything should work fine for decades with regular dusting. Your car stereo system might not be quite as foolproof. Let’s look at five quick and simple tips to ensure that your system works great

1. Radio and Touchscreen Maintenance

The device you will interact with the most is, of course, your car radio. If you have a multimedia receiver, then the touchscreen and volume knob will be the primary contact points. A slightly damp cloth is likely the best way to keep these items looking good. If there’s something stubborn on a touchscreen, a product like Whoosh! is a perfect choice. Spritz a little of this cleaner on a soft microfiber cloth, and you’ll be able to get it looking like new. You can wipe any dust off the instrument cluster while you’re at it.

Never spray any liquid directly on the screen. If dust is caught in the corners of the screen, pick up a makeup brush from a dollar store. These are soft enough to prevent any damage to the screen. This cleaning process also works great for laptops and smartphones.

While checking the screen, make sure the radio is still solid and secure in the dash. Push on the corners of the chassis (not the screen) with a finger. If it moves, something might need tightening behind it. Please drop by the shop that did the installation and book an appointment to have them check it out.

Car Audio Maintenance
The best way to keep your radio’s display looking great is to use a product like Whoosh! on a soft microfiber cloth.

2. Amplifier Maintenance

In most cases, a well-designed amplifier will happily play without trouble for years or even decades. You will want to start by ensuring that the amplifier or amplifiers remain secure in the vehicle. Once again, please give them a gentle push or tug. If they move, get with the shop that installed them.

Next, inspect the amplifier and the area around it for signs of water damage. If an amp is mounted in the corner of the trunk, water from a leaky seal can cause problems. Water and salt damage from slushy boots can cause trouble if the amp is under a seat. If you see signs of water on the amp, find out where it came from. Make sure everything is dry, especially a wooden amp rack.

Check all the wiring to and from the amp. Do the connections look solid? Do you see any signs of excessive heat? If anything looks like it might be loose or if plastic has started melting, consult with the installer immediately. Some types of wiring, especially copper-clad aluminum, can loosen over time and cause poor connections. Terminal blocks can get very hot when these connections get hot, and plastics will melt.

Car Audio Maintenance
A well-constructed amp rack like the one Mobile Edge in Lehighton, Pennsylvania, built for this Ford Mustang will keep the electronics solid and secure.

3. Power and Ground Connections

Though this is an extension of an amplifier inspection, pop the hood and look at the connections to the battery. Pull on the power wire (gently). If any connectors move, then something needs to be tightened.

Check the fuse holder. Is it still secure? Was it ever secure? The electrical connections will be stressed if it’s flopping under the hood. Make sure a reputable shop mounts the fuse holder securely.

Check the ground connection in the trunk or under a seat. These are notorious for corroding, resulting in amplifier failure from power starvation.

If you see any signs of green, white or blue corrosion on the wiring or battery terminals, there might be an issue with the battery or water getting into the wiring.

Car Audio Maintenance
A great way to end up with a bad ground is to use self-tapping screws. If you see this, have it replaced with a bolt and Nylock nut. Image: Reddit user AceStrawberryWolf

4. Subwoofer Enclosures

While the other items are likely safe to check once or twice a year, this one should be done every month. If you have a subwoofer in the trunk or cargo area of your car, truck or SUV, make sure it’s secured solidly to the vehicle. In the event of a severe accident, a subwoofer enclosure flying through the vehicle could be enough to seriously injure you or a passenger.

Using a simple hook-and-loop fastener isn’t enough. In an accident, forces from the deceleration can easily exceed 10 or even 20 Gs. This would make a 30-pound subwoofer enclosure act like it weighs 300 to 600 pounds. Little plastic hooks (on the hook-and-loop fastener) won’t keep it in place.

While you’re inspecting the subwoofer enclosure, push gently and evenly on the subwoofer cones. They should move smoothly. If their motion is rough or scratchy, you have overheated the voice coil and damaged the speaker. Don’t replace the subwoofer with an identical model. Clearly, you need something that’s more capable in terms of power handling and output capability.

Car Audio Maintenance
This Rockford Fosgate subwoofer enclosure is secured by a board strapped to the baby seat latch mechanism.

5. Speakers

Without taking your car or truck apart, checking the condition of your car’s audio speakers can be difficult. The best test is to give them a listen. Put in some good earplugs and play music with a lot of bass at a moderate volume level. Long, drawn-out bass notes from an organ or bass guitar are better than drums. Get up close to the speaker and listen for buzzes and rattles. These could be signs that the cone is interfering with the grille or that the surround has failed. The speaker could also have come loose from its mounting. If you hear anything abnormal, have the installer check it out.

Please never do this without proper hearing protection. You only get one set of ears, and if you damage them, you’ll regret it for the rest of your life.

Car Audio Maintenance
Check the speaker’s performance in your car or truck. Older speakers with foam surrounds are notorious for failing. Image: Reddit user Frank_Jesus

Car Audio System Maintenance Improves Longevity

Thoroughly inspecting your car’s audio system should take about 10 to 15 minutes. If anything seems even the slightest bit abnormal, return to the shop that installed it and have it inspected. Fixing a loose connection now could prevent you from having to replace an amplifier later.

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.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Powering Car Audio Systems at Home: The Ultimate Power Supply Guide

Power Supply

One of the most common questions we receive is whether you can use car audio products, like radios and amplifiers, in the home or shop. The answer is a resounding yes! However, the real challenge lies in finding a suitable power supply, especially for high-power amplifiers. We’ve recently dedicated a significant amount of time to researching power supplies for an upgrade to our lab. Understanding what a power supply is and how it works is crucial.

What Does a Power Supply Do?

What does a power supply do? Typically, it takes a voltage like the 120-volt AC we have in our homes, shops, and offices and converts it to something we can use to power an electronic device. A laptop computer might have an 18- or 20-volt DC power supply. A desktop computer power supply provides +12V, -12V and +5V. Some even supply 3.3 volts and -5 volts DC. The little wall adapter that used to come with an iPhone provided 5 volts – the standard for USB charging.

Power Supply
An example of a 750-watt power supply designed for a desktop computer. Image: Corsair

It should be clarified that there are many types of power supplies. For example, an X-ray machine might need 200,000 volts, mass spectrometry systems may need 30,000 volts, and the microwave oven in your kitchen around 2,100 volts, but some are as high as 2,800 volts. Not all power supplies step the supply voltage down, and not all produce DC voltages.

Power Supply
This lab-grade power supply can provide 500 volts DC for testing vacuum tube circuits.

If you thought we were talking about the power supplies that are part of an amplifier, sorry to mislead you. They also do a voltage conversion. They take the 12 to 14 volts available from the vehicle’s electrical system and convert it to the rail voltages in an amp. This might be +20 and -20 volts for an 800-watt subwoofer amplifier.

How Are Power Supplies Rated?

Power supplies are rated based on the total current they provide, or more specifically, wattage. For example, a multi-outlet USB-C charger for a modern smartphone might deliver 40 or 60 watts of power. A USB port might be rated for 3.1 amps of current, which works out to 15.5 watts. Some USB-C devices can charge at 20 volts and 5 amps of current, which is 100 watts.

Power Supply
This Anker USB-C charger can supply up to 65 watts of power and features 45- and 20-watt USB-C ports, along with two USB-A ports.

If you’ve shopped for a new power supply for a computer, you’ll see supplies are available in power delivery ratings from 500 watts up to about 1,650 watts. The latter is the upper limit of how much power a device can draw from a 120-volt wall outlet. The math there is 120 volts times 15 amps equals 1,800 watts. Drop in 90% for efficiency, and you have 1,620 watts. Suppose you have a liquid cooling system, several case fans, RGB lighting, a CPU that needs lots of power, a beefy video card and several external drives. In that case, you need a power supply large enough to ensure that it all runs reliably.

Refocusing on car audio equipment, it’s not uncommon for us to install a subwoofer amplifier rated for 1,000 watts of power. Assuming it’s of reasonably good quality, that amp might draw 1,175 watts of power from the vehicle charging system. At 13.6 volts, that would be 86.5 amps of current. As an aside, if the amp isn’t efficient, it might draw as much as 120 amps to produce the same output. Amplifier efficiency is crucially important.

Let’s say you want to run this 1,000-watt amp in your living room to power a pair of car audio subwoofers in a ported enclosure. It would be best if you had a 100-amp power supply. We’ve been researching these extensively for the last few months as part of an upgrade to our lab. If you want a true 100-amp, 12-volt (1,200-watt) power supply, you’ll likely need to connect it to a 20-amp circuit. Be very wary if the supply claims it can produce 100 amps from a 15-amp circuit.

Power Supply
This 1,400-watt power supply from Acopian can provide up to 100 amps of current at 15 volts DC.

Linear Versus Switching Power Supplies

Decades ago, the standard for car audio power supplies for display boards was the Orion PS 100A. This thing weighed what felt like 90 pounds and could pop a 15-amp circuit breaker at will. However, it provided clean and reliable power to ensure that the subwoofer amplifiers on display boards sounded awesome. Specifically, this was a 100-amp supply with current limiting and output voltage adjustments.

Power Supply
This PS 100A power supply belongs to diyma.com user kbanford. This monster weighed a ton because of its massive internal transformer.

The massive weight of the supply was attributable to the giant transformer inside it. This was a linear power supply, so the transformer needed to be massive to deal with the vast amounts of current that would flow through it.

These days, you can get a 1,400-watt (100 amps at 14 volts) power supply that fits inside a computer case. You could fit two of them in a typical backpack. These are also available as 1U-sized rack-mount units, just like a processor in the effects rack for a band. So, why are power supplies smaller now? Most of them are called switch-mode supplies. They work differently than their linear cousins. As expected, they have their benefits and drawbacks.

Power Supply
Rack-mount power supplies such as this unit from TDK-Lambda offer impressive power and efficiency from a small chassis.

Linear Power Supply Operation

Let’s discuss how a linear power supply works without getting into university-level electronic design. We’ll be talking about supplies that take the 120-volt AC power from the wall and convert it to something like 13.6-volt DC to power car audio equipment.

Power Supply
A simple block diagram of a linear power supply.

Power supply operation is quite simple. The process starts by taking the 120-volt AC and passing it through a transformer to reduce the voltage. The transformer’s input and output will be a 60-hertz sinusoidal waveform.

Power Supply
The input (violet) and output (green) waveforms on either side of the transformer.

After the transformer lowers the voltage, we feed the AC waveform to a rectifier. This circuit, typically comprised of four diodes, inverts the negative half of the waveform, producing a positive voltage with lots of ripples – it sort of looks like waves in an ocean.

Power Supply
The rectifier stage’s output shows the negative part of the sine wave inverted.

From there, the noisy DC signal passes through the filter stage, which typically consists of a few large electrolytic capacitors. As we should know from talking about passive crossovers, capacitors oppose changes in voltage. As such, they smooth out the ripples to produce a fairly clean DC voltage.

Power Supply
A bank of electrolytic capacitors smooths the rectified signal. Note: Vertical scale increased for clarity.

Finally, we get to the regulation stage. In a linear power supply, this stage is usually handled by a single large or multiple medium-sized transistors. This circuit works as a variable resistor, ensuring that the output voltage stays at a set level. The transistor adds resistance to the circuit based on a feedback loop to ensure that we get our desired 13.6 volts.

Power Supply
Voltage regulation in a linear power supply is handled by a transistor or a bank of transistors acting as resistors.

Benefits and Drawbacks of Linear Power Supplies

You might choose a linear power supply for high-current applications for two reasons. First, they’re usually relatively quiet regarding electrical noise on the output signal. We call this noise ripple, as once again, it’s like small waves in a lake. Second, linear power supplies offer excellent transient response. They can keep up with sudden power demands quite well, making them ideal for high-current audio applications.

Unfortunately, with the good comes some drawbacks. Linear power supplies are large, expensive and inefficient. They waste significant energy as heat because of the regulation transistors operating as variable resistors to maintain the chosen output voltage. Second, the power supplies require huge, heavy and expensive transformers. This is primarily because of their inefficiency. If they waste 70 to 80% of the power they consume as heat, the transformer must supply large amounts of energy to have enough left over for the load (amplifier).

Switch-Mode Power Supplies

The other type of power supply available is a switch-mode power supply, or SMPS for short. These are, by far, the most popular type of power supply you’ll encounter. Their operation philosophy is similar to that of a linear supply, but rather than wasting energy with a resistive regulation stage, they use pulse-width modulation to control the power going into the transformer.

Power Supply
The basic block diagram of a switch-mode power supply.

An SMPS starts with a bridge rectifier that inverts the negative side of the input sine wave. Violet is the 120 VAC input, and green is the rectified output.

Power Supply
A bridge rectifier converts the negative pulse of the input waveform to positive.

Electrolytic filter capacitors smooth the signal before it’s passed to a transistor or MOSFET driven by a pulse-width-modulated control.

Power Supply
Capacitors smooth the output of the rectifier so that the waveform resembles a DC voltage.

The next step is to chop up the signal into tiny pieces again so we can pass it through a transformer to reduce the voltage. Why not just do this at the beginning? Well, the pulse-width modulating controller is fed by a signal from the circuit output. It decides how much duty cycle is needed to deliver an appropriate voltage and current. So, rather than all of the input voltage going to the transformer, we can feed minute amounts of power if there is no load or moderate amounts if there is a heavy load. Because the PWM control will determine the circuit’s power, we aren’t wasting energy through a resistive regulator like the linear supply. As such, the transformer can be much smaller and operate more efficiently.

Power Supply
The input to the transformer is pulse-width-modulated DC.
Power Supply
The output of the transformer is a lower-voltage triangle wave.
Power Supply
A second bridge rectifier inverts the negative portion of the triangle waveform.
Power Supply
Electrolytic capacitors smooth the rectified signal to create a reasonably smooth DC voltage.

Benefits and Drawbacks of Switch Mode Power Supplies

As we mentioned above, the most significant benefit of a switch-mode power supply is that only the power required by the load passes through the transformer in the middle of the circuit. This means the supply operates much more efficiently, so the parts and case can be much smaller. Switch-mode supplies can easily be 90% efficient, wasting only 10% of the input energy as heat.

As happens with electronic circuits, there are drawbacks as well as benefits. Switch-mode supplies have more noise or ripple on the output. Looking closely at the final waveform above, you can see some bumps in the output. These aren’t there by accident. It’s not uncommon to have half a volt of noise on the output of a high-power switch-mode supply. Most good quality car audio amplifiers have an inductor and capacitors on the input power connections to filter this noise. However, not all do.

The second drawback is that there are many components (or blocks) between the output and the feedback signal to the PWM controller before the transformer. If an amplifier suddenly demands a large amount of power, the output voltage can droop, dip or sag before the supply can bump up the pulse width and compensate. You can consider this a slow response time. Switch-mode supplies aren’t the best choice if you want the best impact at maximum volume from an amplifier.

Picking a Power Supply for Car Audio in the Home

The explanation of power supply operation was more detailed than planned. Nevertheless, now you have the information. In terms of picking a supply to use a radio in your home or garage, you need something that can provide about 180 watts of power, or 15 amps at 12 volts. We’d suggest finding a 14- or 15-volt supply. Most car radios are acceptable up to about 16 volts, so the extra voltage means the radio will draw less current.

If you want to power a large subwoofer amplifier, you’ll need to figure out how much current the amplifier draws at maximum power at the load you plan on using. You can often use the fuse ratings on the amp as a guideline. For example, if the amplifier has 80 amps worth of fusing, you’ll need a supply that can deliver about 14 volts and 80 amps of current, a little over 1,100 watts. A solution like the Stinger SPS70 would be a just-adequate solution. We’ve used a pair of SPS80 supplies on the BestCarAudio.com test bench for several years with good success.

Power Supply
The Stinger SPS series of power supplies offers good solutions for running high-power car audio components in your home or office.

Now, why are there much more expensive power supplies available? For example, the go-to for car audio displays has been the Samlex SEC-100BRM. This supply offers 100 amps of current but might cost twice as much as the Stinger. Why? Well, it provides better voltage regulation under dynamic loads. Further, there is less noise in the output signal. The BestCarAudio.com lab has a Samlex supply for making noise and distortion measurements on high-end amplifiers.

Power Supply
The Samlex SEC-100BRM is an excellent power supply with good voltage regulation.

Some Bad Ideas to Avoid

We’ve encountered several conversations online where the original poster planned on using a car battery in their home to provide supplemental current to the amplifier. In spite of our warnings about hydrogen gases being released during charging, they planned to proceed with this bad idea. Please don’t put a car battery in a living space. If you want to supplement the instantaneous power delivery to an amplifier, add a high-quality stiffening capacitor. Suitable stiffening capacitors are hard to find, but they are out there.

Finally, be very careful with the wiring. Car audio amplifiers can consume massive amounts of current. A loose connection can heat up and cause damage quickly. Honestly, you’re much better off buying used DJ or PA gear. You can pick up a used QSC or Crown amp from the Facebook Marketplace for less than you’d pay for an entry-level power supply. This solution is also dramatically more efficient and safer. I know, bummer, eh?

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.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Car Audio Subwoofer and Speaker Inductance – Less Is More!

Speaker Inductance

Even though most car audio speakers are chosen without regard for genuine performance, our goal of educating consumers remains steadfast: If you’re searching for a high-quality car audio system, understanding how speakers work and what differentiates the great from the mediocre is essential. In this article, we’ll explore the topic of speaker inductance, what affects it and why it matters to what you hear.

What Are Inductors?

As an introduction, you should review our full article on how inductors are used in car audio systems. This will give you a good overview of how they work.

In short, an inductor is a coil of wire that opposes the flow of alternating current. Direct current can pass through an inductor nearly unhindered. However, the magnetic field created in the inductor resists the change in polarity associated with AC signals. As such, inductors act like a frequency-dependent resistor to AC. We can use this characteristic as a benefit to limit the high-frequency information sent to a speaker or reduce noise in an electronic component.

In this article, we’re going to talk about speaker inductance. Unfortunately, the voice coil in the center of a speaker is also an inductor. It’s a tightly wound coil of wire wrapped around a magnetically conductive core. Aside from a small air gap, it’s no different than the inductors we use in passive crossovers.

Speaker Inductance
An example of a four-layer voice coil used in a car audio subwoofer.

What Does Inductance Do?

As mentioned in the article linked above, inductor reactance, or opposition to the flow of AC signals increases as frequency increases. This results in less current flow. As such, if we have a speaker with a very inductive voice coil, less current will flow through the speaker at higher frequencies. This means the speaker produces less sound at high frequencies as the magnetic field that’s formed is weaker. Again, this is identical to wiring an inductor in series with a speaker to create a crossover.

Subwoofers have the largest voice coils and, as such, typically have relatively high inductance values. As the number of layers in a voice coil increases, so does the inductance. For example, a 1.5-inch voice coil with four layers might measure 3.7 millihenries.

If a speaker designer wants to increase power handling, then a voice coil with more layers of wire will do the trick. The drawback is that the winding will have more inductance and, consequently, less upper bass and midbass output. The inductance also starts to cause a phase shift if the output of the signal as it behaves as a first-order low-pass filter. At the point where the inductance reduces output by 3 dB, the signal will be shifted by 90 degrees. This phase shift complicates getting the midbass to blend with the woofers.

The same thing happens with midrange speakers. If the design engineer wants more power handling, the driver needs a larger voice coil winding. The differences in inductance can be quite staggering and have a clearly audible effect on upper midrange output and how the driver blends with the tweeter.

Speaker Inductance
An example of a two-layer, 16.8-mm diameter voice coil for a midrange speaker or small woofer.

Woofer Voice Coil Inductance

Let’s do some math in a spreadsheet to simulate what different voice coil inductances do to affect subwoofer output. We’ll start with a low-tech, high-power handling driver, as you’d find from popular internet-only brands. We quickly found a 4-ohm subwoofer rated for a few thousand watts of power handling with a voice coil impedance of 5.5 millihenries.

When manufactured by a reputable brand, a typical consumer-grade subwoofer rated for around 500 to 700 watts of power has around 3.7 millihenries of inductance. Now, if a company is serious about sound quality, it will add inductance-reducing features like a copper or aluminum shorting ring and a copper T-yoke cap. Drivers like this might only have 0.33 millihenry of inductance.

The chart below shows how the voice coil inductance attenuates the output of the three woofers. This graph doesn’t consider the cone’s mass, which, if significant, will also attenuate midbass and midrange output.

Speaker Inductance
This graph shows the output of the three subwoofers we described above based on the midbass attenuation caused by the difference in voice coil inductance levels.

If we refer back to the discussion about a -3 dB point, we can see that the high-inductance woofer is -3 dB at a really low frequency of 47.8 hertz. The typical speaker with an inductance of 3.8 millihenries plays out to 71 hertz. Finally, the speaker with the inductance management features is flat-out amazing at 795 hertz.

Translating Measurements in Sound

So what do high-inductance subwoofers sound like compared with the low-inductance designs? It should come as no surprise that they don’t sound as tight. The reduction in midbass output attenuates upper bass frequencies. As mentioned, this complicates getting the subwoofer to blend with the woofers in the doors. For example, kick drums or large floor toms lack attack or impact. The low-frequency thud of a kick drum might be clear, but the higher-frequency information of the hammer hitting the skin will be lessened. Yes, we can equalize the system to play these frequencies at higher output levels, but the clarity of a high-inductance subwoofer simply outperforms low-inductance designs.

Inductance in Midbass Drivers and Woofers

The same inductance criteria that affect subwoofers can also reduce the upper midrange clarity of woofers and midrange drivers. Most audio system target response curves call for a flat response out to 3 or 4 kilohertz. We can see from the graph below that high-power-handling speakers without inductance management features like shorting rings start to roll off well below where they would cross over to a tweeter.

Speaker Inductance
Woofer output based on voice coil inductance.

The green trace is a 6.5-inch woofer with an inductance of 0.43 millihenry. This a robust driver with a 50-mm voice coil and a continuous power handling rating of 150 watts. The second trace in blue represents a 6.5-inch woofer with a measured inductance of 0.24 millihenry. Finally, we have a third 6.5-inch woofer with an inductance of 0.13 millihenry. This driver has a copper pole piece cap and an aluminum shorting ring under the top plate. Based on their inductance, these drivers have -3 dB frequencies of 620, 1,100 and 2,100 hertz.

Speaker Inductance
The Rockford Fosgate T4 Woofer’s inductive damping heat sink minimizes voice coil inductance to 0.161 millihenry.

Start Your Speaker Shopping with Research

If you’re shopping for truly magnificent-sounding speakers, start the process with some research. Create a table of speaker options in the sizes you want, then look up their voice coil inductance. Of course, this is not the only feature to consider. A low Total Q (Qts) can also tell you a lot about how a speaker will sound. So can frequency response charts. Once you have a short list of car audio speakers, do some listening evaluations at local specialty mobile enhancement retailers. This head-start will help you choose a speaker system that sounds genuinely amazing.

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.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Car Audio Battery Fuse Size and Purpose

Battery Fuse

If you’ve looked at an amplifier installation kit, you’ll see it comes with about 17 feet of power wire, a shorter length of ground wire and a fuse holder. The intent of this fuse holder is for it to be installed as close as possible to the positive battery terminal. As for the fuse size, should it be the same as the fuse in your amplifier? Likely not. Read on to learn why.

Overcurrent Protection Devices

When it comes to overcurrent protection devices in car audio systems, there are two main contenders: circuit breakers and fuses. Our extensive testing has revealed that circuit breakers, while effective, tend to waste a bit more voltage than their fuse counterparts. Moreover, there’s a risk of circuit breakers not opening when an overcurrent condition occurs. That’s why we strongly advocate using ANL and Mini-ANL fuses to safeguard our vehicles.

A fuse is a simple device in that it’s a piece of metal with a specific area through which all the current going to the load passes. We know that all conductors, be they copper, aluminum or an alloy, have a specific resistance for a given area. As such, fuses are sized so that their resistance will cause the fuse to melt when the current flowing through the device exceeds a certain threshold. Once melted, the current no longer flows to the load.

Battery Fuse
The little S-shaped piece of metal viewable through the window is designed to melt when 150 amps of current flows through this fuse.

Why Do We Need a Fuse at the Battery?

When a local mobile enhancement retailer upgrades our vehicle with an amplifier, they run a large-gauge power wire to the battery’s positive terminal and ground the amp’s negative terminal to the chassis. In some cases, especially in vehicles built with aluminum or adhesives, the negative terminal must also go to the battery. The purpose of the fuse is to protect the battery from an overcurrent condition.

What could cause an overcurrent condition in the amplifier power wire? Well, if the wire comes loose from the amp and drops onto the vehicle’s body or touches the negative terminal, a lot of current will flow. Without a fuse, the wire will likely heat up quickly, the jacket will melt, and there could be a fire. Likewise, if the power wire is run across a sharp edge like a hole drilled in a piece of metal, that could cut into the wire and potentially short the wire to the ground. If you’re in an accident where the side of the vehicle is crushed, the power wire might be pinched by the folded metal and be shorted to the ground. Any of these conditions will result in a mess if no overcurrent protection device is installed at the battery.

Battery Fuse
In the unlikely event your car is involved in an accident, the battery fuse will prevent current from flowing through the power wire if it’s pinched. Image: Cleetus McFarland YouTube Channel

Why Are There Fuses in Car Audio Amplifiers?

Contrary to popular belief, a fuse in a car audio amplifier isn’t to protect the amplifier. Fuses are there to protect the vehicle battery in the event the positive and negative power connections to the amplifier are reversed. Because of how the switching devices in a power supply work, there will be a short circuit if the power connections are reversed. With no protection device, the switching devices will explode violently. The fuse or fuses are not going to prevent damage to the amp if a single switching device fails during regular operation.

So, how are the fuses on an amplifier chosen regarding their current capacity? They need to be large enough to ensure that the amplifier can produce its full rated power without them blowing. We’ve tested a few amplifiers that will pop the included fuses when all channels on the amp are driven at full power into their minimum impedance with test tones. This scenario is different from playing music, so it’s not an issue.

What Size Fuse at the Battery?

To recap, the fuses on the amp protect it from catastrophic failure in the event of a wiring accident. What size should the fuse be at the battery, and what’s its purpose? The fuse at the battery protects the power wire. As such, it should be sized to prevent the wire from carrying more current than it can handle without overheating.

We know there are many official wire sizes, and that wire should be made of copper. However, we also know that there are many mystery wire diameters and that many inexpensive amplifier installation kits use copper-clad aluminum wire. Unfortunately, we don’t know how much aluminum is in these kits, so an educated assessment of the wire resistance is impossible.

The ANSI/CTA-2015 standard for car audio power wiring suggests we should have no more than 0.25 volt of drop across the wire. This will, of course, be for steady-state current requirements. Nevertheless, we’ll use it as a reference for our calculations. In terms of power wire length, we will provide data for 10- and 16-foot runs. Ten feet is likely adequate to connect an amplifier mounted under a seat to the battery under the hood. Sixteen feet is usually enough to mount an amp in the trunk. The table below shows the maximum current the wire can pass for the given lengths, resulting in a roughly 0.25- to 0.26-volt drop.

Battery Fuse

As you can see, the maximum current decreases with length. This is because the resistance increases, which results in more voltage drop.

While the above chart is logical, it is perhaps too optimistic about the reality of modern car audio system design. We know of many systems where a run of 4 AWG wire is subjected to well over 100 amps of current. Sure, the amp won’t see the full battery or alternator voltage, but the cable doesn’t melt and catch fire. So, here’s our recommended maximum fuse size chart.

Battery Fuse

Why Not Use a Smaller Battery Fuse?

Could you use a smaller battery fuse than we’ve recommended? Absolutely. However, there’s an interesting reason why you might not want to. As mentioned, fuses have a specific resistance that causes them to blow when a specific amount of current passes through them. Fuses rated for larger amounts of current have less resistance. As such, less voltage drops across the fuse, and more is available to feed the amplifier. More voltage will result in the amplifier being able to produce more power before it starts clipping.

Fuse Location

Decades ago, the International AutoSound Challenge Association established a rule that said the fuse in a car audio system should be within 14 inches of the battery. Sadly, many people took this to mean that the fuse should be 14 inches from the battery. In reality, the fuse should be as close as possible to the positive terminal to provide maximum protection. Having a fuse 10 to 12 inches away might not provide adequate protection in a front-end collision.

We like the idea of fuse holders that are integrated directly into battery terminals. This design provides the most protection possible should something go wrong.

Battery Fuse
Audison’s BBC 41PF is a fused battery terminal made from solid brass. It has a fused 1/0 output and unfused 4-AWG and two 8-AWG connections.

Ensure that Your Car Audio System Is Protected

While most professional car audio installers know how to adequately protect your vehicle from damage because of a short-circuited power wire, some might need guidance. Before you let anyone work on your vehicle, discuss what type of overcurrent protection device will be used and where it will be installed. A proper battery fuse is crucial to preventing additional damage should something go wrong.

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.

Filed Under: ARTICLES, Car Audio, RESOURCE LIBRARY

Product Spotlight: AudioControl A600.4

AudioControl A600.4

If you have been around the car audio industry for as long as we have, then you have likely used an audio processor in your vehicle. This veteran company is recognized worldwide for its line output converters, equalizers and crossovers. A few decades later, the brand has introduced several series of amplifiers. Their latest offering is the Altitude Series. In this spotlight, we’ll check out the four-channel A600.4 amp.

AudioControl A600.4 Specifications and Features

The A600.4 four-channel amp is rated to produce 100 watts of power per channel when driving four-ohm loads. That output increases to 150 watts per channel when driving two-ohm loads. When each pair of channels is bridged to a four-ohm load, the amp produces 300 watts of power.

With respect to performance, the amp has a THD+N specification of <0.21% and a signal-to-noise ratio of 107 dBA referenced to full power.

Let’s start with a unique feature included in the A600.4 – Valet mode. When a 12-volt signal is applied to the Valet input, the maximum power the amp can produce is reduced to 25% of its maximum output. The malfunction indicator LED will illuminate orange when the amp is in Valet mode. If you are concerned about someone abusing your car audio system, this feature is perfect for keeping your speakers safe.

The A600.4 is also equipped with AudioControl’s Great Turn-On (GTO) circuit. The amp can be activated by applying 12 volts to the remote input. Alternatively, when in GTO mode, the amp will detect the ~6-volt bias on the speaker wires of a factory-installed or aftermarket radio. If your installer is integrating the amp into a vehicle with a full-bridge amplifier, Audio mode will monitor the inputs for the presence of an audio signal to wake the amp up.

Another unique feature of the A600.4 is its use of Linkwitz-Riley alignments on the crossovers. While the slopes are still shallow at 12 dB / Octave, they will sum smoothly around the crossover point because the signal will be -6 dB at the knee frequency. Butterworth crossovers are only at -3 dB at the crossover point, which results in a 3 dB bump when the acoustic signals sum. In short, your system will sound better and have improved clarity around the crossover frequency with this design.

The amplifier is based on an aluminum extrusion and features uniquely styled end-caps for a clean appearance. A removable panel on top of the amp conceals all the signal adjustments and the set screws for the power and speaker connections.

All connections are made along the front edge of the amp using high-quality terminal blocks for 4-AWG power and ground, and 12-AWG speaker wire connections.

AudioControl A600.4
All connections are made along the front edge of the amp for a tidy installation.

Signal Processing Information

Each pair of channels has a sensitivity control that is adjustable from 0.5 to 6 volts on the RCA inputs and 1.5 to 20 volts on the speaker-level inputs. The speaker inputs are on an eight-pin Molex plug, and AudioControl calls this the LC Direct connection. The amp has a two or four-channel input switch. In two-channel mode, the signal on channel 1 (LC Direct or RCA) is copied to channel 3, and the signal on channel 2 is copied to channel 4. This is ideal if you are connecting that amp to something like a Bluetooth streaming device as a signal source. Each pair of channels has a Max input indicator. This LED will illuminate when the input is maximized and should flash occasionally when playing music recorded at high volume levels.

AudioControl A600.4
The A600.4 has clean lines and a modern aesthetic. It’s also small enough to fit under the seat of most vehicles.

The crossover on each pair of channels is adjustable between 50 and 500 Hz, or when the x10 switch is enabled, 500 to 5 kHz. This is enough range to handle subwoofer to midrange speakers, or midrange to tweeters. The crossovers on both channel pairs can operate in high- or low-pass mode to ensure maximum system design flexibility.

The amp has an RCA output terminal that can be used to feed an audio signal to an additional amplifier like the A800.1 800-watt monoblock to power a subwoofer.

Finally, there is a connection for an optional ACR-1 remote level control. When connected, you can adjust the output level of channels 3 and 4 to suit your mood or the music you’ve chosen.

AudioControl A600.4
Controls and set screws for the terminals are concealed behind a removable panel on top of the amplifier.

Upgrade Your Car Audio System with AudioControl

If you are shopping for a well-equipped four-channel amplifier to enhance your car audio system, drop by a local authorized AudioControl retailer and ask about the new Altitude Series A600.4. You can find a dealer near you using the locator tool on the AudioControl website.

Be sure to follow AudioControl on Facebook, Instagram and YouTube to stay up to speed with all their new products and solutions.

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.

Filed Under: ARTICLES, Car Audio, PRODUCTS, RESOURCE LIBRARY Tagged With: AudioControl

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