Car Amplifier FAQ

Found this, thought it had some good info and useful calculations one could use for his/her sound system.

Q: Where can I mount my amp?

A: Since space is at a premium in most vehicles, it's important to find just the right spot to mount your amp. Our two favorite locations are under a seat or in the trunk. Under-seat mounting is space-efficient and keeps the amp hidden from view. It also lets you run shorter cables from your receiver. A trunk-mounted amp requires longer power and signal cables, but is safely hidden and closer to rear speakers and your subwoofer.

Warning: removing your seat could deactivate your vehicle's SRS system.

Q: My car audio amplifiers all came with fuses. Why do I need to add an additional fuse at the battery? And how big a fuse do I need?

A: The answers to most questions about fuses include the word "safety." While most car audio amplifiers do come with their own fuses, these fuses are designed to protect only the components themselves. There are a few other bases a safe installation should cover.

Q: Why fuse at the battery?

A: Installing a fuse of the proper amperage on your power cable protects everything between the fuse and your gear from a short circuit. A short circuit occurs when a current-bearing wire makes contact with bare metal (like your car chassis). Because your entire car chassis can be considered "negative" or ground, you can think of a short circuit as positive touching negative. You definitely don't want this to happen, but if it does, a properly installed fuse will prevent a fire or other damage. A fuse does its work by "blowing" and stopping the flow of current. So, given the alternatives, "blowing a fuse" is a relatively good thing. You can optimize the protection your fuse provides by installing it closer to the battery — that increases the length of the protected cable behind it. Twelve to 18 inches from your battery is the distance we recommend.

Q: How big should the fuse be?

A: If you're installing just one amplifier, the fuse at the battery should simply match or slightly exceed the fuse rating of the amplifier itself. If you're installing two or more amplifiers, just add their fuse ratings together and install a fuse rated roughly equal to this sum. Generally, it's better to go slightly higher than lower, but a margin of five amperes is acceptable.

Say you have three amplifiers, two with fuse ratings of 20 amps each and one with a fuse rating of 25 amps. In this case, you can safely go with either a 60 or 70 amp fuse. (Of course, if your system is powerful enough to demand that you install a heavy duty fuse, it's important that your power and ground wire be of an appropriately heavy gauge as well.)

Q: Do I need a separate fuse block too?

A: A safe system will have the right fuses installed at each amplifier and also on the power cable by the battery. But if you've ever taken a peek at some competition-style car audio systems, you may have noticed fuses at a third location — in a fuse block by the components. Sure this hardware looks good, but is it necessary?

Unless your amplifiers are among the few that don't come with fuses installed, the answer is no. The reason you see these "redundant" fuses is that in the early days of car audio competition, amplifiers frequently didn't include their own fuses, or if they did, often hid them behind panels that were hard to get to, especially in the heat of competition.

Today, the use of such fuse blocks is largely a matter of style. But that's OK — looking cool definitely counts. In the world of car audio, it's a close third, right behind being safe and sounding great.

Q: What wiring do I need to hook up my amplifier? Does any of it come with the amp?

A: Amplifiers generally do not include the wiring necessary to hook them up. However, we offer a number of wiring kits that will provide everything you need to send signal and power to your amp.

You need enough power cable to run from your car battery's positive terminal through the firewall to the amplifier. Be sure to install an in-line fuse or circuit breaker near the battery. Without one, an accidental short circuit could pose a fire hazard and damage your amp (not to mention your car).

You also need another length of the same gauge cable to serve as your ground wire. You won't need as long a ground wire because your grounding point should be relatively close to the amplifier.

The last wire you need for powering the amp is a turn-on lead. It doesn't need to be as thick as the power and ground wires (18 gauge should be fine). It runs from the remote turn-on lead at the back of your receiver to the remote terminal on the amp. When connecting these wires, be sure to use crimp-on spade or ring terminals to get the best signal transfer.

The audio signal travels from the back of your receiver to your amplifier through an RCA patch cable. Your patch cable should be long enough to reach the amp but not so long that it has a lot of slack and could become kinked over time.

At the other end of the amp, you'll need speaker wire. Generally 14, 16, or 18 gauge wire should be sufficient. Keep in mind that current flows more easily through thicker wire. (The lower the gauge number, the thicker the wire.)

Q: What size power and ground wires do I need for my amplifier?

Using thicker power and ground cables will allow your amplifier to draw the juice it needs from the battery more easily.
A: You'll find all the power and ground cable you need available in our online Installation Store. Before you can decide on the appropriate gauge wire for your installation needs, you need to figure out the current demand of your system.

To do that, you must ascertain the approximate current draw (in amperes) of your amplifier (or amplifiers). First, calculate the total power of each amp (multiply the number of channels by the number of RMS watts per channel). If you have multiple amps, add up the total power figures to arrive at a grand total. Second, double your grand total power figure. And, finally, divide by 13.8 — the result is your system's approximate current draw in amperes.

Q: What's this thin blue wire for?

A: The thin blue wire is called the turn-on lead, as it carries a signal that turns on your amplifier. The turn-on lead runs between the amp and your receiver. You wouldn't want your amp to be on all the time, draining your battery dead every time you park. The turn-on signal triggers an electronic switch inside the amp that powers it on whenever the receiver turns on. The turn-on lead must be connected properly in order for your amp to power up.

Q: How much air space do I need around my amplifier?

A: An amplifier produces heat, which its heat sink absorbs and dissipates. You should leave a few inches of air space around the amp so that it stays as cool as possible. When mounting an amp on a side wall (vertically), make sure that the fins on the heat sink are also running vertically so the heat escapes more easily. Don't mount an amp upside down — the amp will not be able to dissipate heat effectively, and overheating can damage or destroy your amp!

Q: How do I hook up multiple amplifiers?

A: You must supply power from your battery to every amplifier in your system. You could run a separate power wire to each amplifier, but a power distribution block will give you a cleaner installation with less potential for noise problems.

Let's say that you want to install a 200-watt mono subwoofer amp, a 75W x 4 amp for your door and rear deck speakers, and a 30W x 2 amp for your dash speakers — 560 watts of total system power. Run a single 4-gauge power wire from your battery to a 3-way (or 4-way) distribution block next to your amps. From the block, 8-gauge cables supply power to your subwoofer and multi-channel amplifiers, while a 10-gauge wire feeds the 30 x 2.

Ground your amplifiers in reverse fashion — one 10-gauge and two 8-gauge ground cables run from the three amplifiers to a grounding block. A 4-gauge ground cable connects the grounding block to your vehicle's chassis. You'll need a relay on the turn-on lead to protect your receiver. A relay connected to the power antenna lead draws little current from the receiver, but supplies enough power to turn on all your amps simultaneously.

You can use RCA patch cables to send signal from your receiver to your amplifiers. A receiver with 3 sets of preamp outputs can provide signal for your front, rear, and subwoofer amps. If your receiver has only one set of preamp outputs, you'll have to use a Y-adapter to provide signal to a multi-amp set, or look for amps with built-in preamp outputs (allowing you to daisy chain the signal from one amp to the next).

Q: My amplifier is hooked up, but it won't turn on. What's wrong?

Check the following:

Do all the other electrical systems in the car work?
Is the receiver turned on?
Is the power cable from the car battery to the amp firmly connected at both ends?
Is the in-line fuse on the power cable near the battery good?
Are the on-board fuses in the amp good?
Is the turn-on lead (usually blue) to the amp from the receiver properly connected? (Set the receiver to the tuner or radio mode. If your amp now comes on, it means the turn-on lead has been wired to the receiver's power antenna lead by mistake and needs to be correctly re-wired to the remote turn-on lead connection.)
Is the ground cable from your amp firmly connected to the car's chassis with no paint or varnish interfering with a clean electrical contact?
If this is a multi-amp system, have you tried powering up just one amp at a time? (The turn-on signal has a limited capacity. In multi-amp systems it is often necessary to use the turn-on signal from the receiver to power a relay, which in turn supplies the turn-on signal to the amps from another power source.)
If the answer to all those questions was yes and your amp still doesn't come on, then perform the following test:

Remove the in-line fuse on the power cable.
Disconnect the turn-on lead from the amp and tape the end so it can't contact any metal.
Take a short length of wire and connect it between the amp's turn-on terminal and its positive power terminal, leaving the power cable connected to the amp.
Replace the power fuse.
If the amp comes on, the turn-on lead wire, or the signal itself, from the receiver is bad and should be repaired. Replacing the turn-on lead usually fixes this. Otherwise you'll need to provide that signal (+12 volts DC) from somewhere else, like the car's fuse box which only gets powered when the ignition's on. You do not want to leave the turn-on lead jumped to the amp's positive terminal because that way the amp will never shut off, draining your car's battery dead.
If the amp did not turn on, you most likely have a damaged amp and need to replace it or contact your dealer to arrange for its repair. One last check - if you have and know how to use a voltmeter, measure the voltage at the amp's power terminal and turn-on terminal. If it reads about +12 volts DC or more, then your amp is bad.
Important Note: For your personal safety, and that of your equipment, always remember to remove the power fuse before disconnecting or reconnecting your amplifier.

Q: How much power do I need to get optimum performance from my car's sound system?

A: Since every car stereo is different, there's no magic "wattage formula." As long as you stay within the recommended power range of your speakers, increasing power will always add richness and depth to your music. Compare a spinet piano to a concert grand. The small piano is good enough to play music clearly, but move up to a grand and you'll gain better tone, greater harmonic detail, and more volume. The larger instrument is simply more powerful.

Here are a couple things to consider, though:

How efficient are your speakers? Your speakers themselves have a direct influence on the overall "power" of your system. If you plan to power your speakers with your in-dash receiver, efficient speakers (sensitivity of 90 dB or higher) will give you more bang for the buck. Installing high-performance component speakers? An outboard amp will generate maximum performance.
Are you adding a subwoofer? Subs need substantial amounts of power to reproduce the lowest tones, so it's essential to use an outboard amplifier with them. You should count on using more power for bass than you use to power all your full-range speakers. If your receiver puts out 20 watts RMS x 4 channels (80 watts total), send at least 80 watts to your sub. Using a 50 watt x 4 amp to drive your components? Dedicate at least 200 watts for bass.
How good is your wiring? Your system's chain of components is only as strong as its weakest link, so don't cheat your amps and speakers with substandard power cable and speaker wire.
Before you buy, consider your car. If you drive a quiet car with the windows up, you'll need much less power than someone who offroads in a Wrangler. Speaker location, extraneous road/car noise, noise damping material, and personal taste are factors that may affect how much power you'll need in your ride.
Q: What's the biggest amp I can hook up to my car's electrical system?

A: Your car's alternator ampere rating determines how powerful an amplifier you can install. Multiply the ampere rating by 40%, and you'll get a rough idea of how much reserve current capacity your car's system has. Next, you'll need to calculate the approximate current draw of the amplifier you're considering installing.

To calculate the current draw of an amplifier, multiply the number of channels by the RMS watts per channel (a 2 channel amp rated at 300 watts RMS per channel would be 600 watts). Double it to account for amplifier inefficiency (600 watts X 2 = 1200 watts), then divide by the average output Voltage of an alternator, 13.8 volts (1200 divided by 13.8 = 87 amps). Since the average music signal requires about 1/3rd of the average power in a test tone, divide by 3 (87 amps divided by 3 = 29 amps). The result is the amplifier's approximate average current draw.

A fast-and-nasty way to ballpark an amplifier's current draw is to divide the total fuse value of the amp by two. For amplifiers with multiple fuses, the rating of all fuses provided with the amp must be added together. This will likely produce a significantly higher estimate than using the proper formula. Although inaccurate, this will err on the side of safety.

Finally, compare the amplifier's approximate current draw to your vehicle's reserve current capacity to determine if the electrical system can support the amplifier.

If all those numbers are a bit much, here's a simpler way to think about it: an alternator capable of producing 65 amperes is usually adequate for systems up to 270 X 2 watts RMS. A compact car with a 35-amp alternator can accommodate around 150 X 2 watts of power, while a Sport Utility with a 145-amp alternator can handle a 600 X 2 watt system. A capacitor can help if your system is drawing a little too much power. Car audio competitors often replace their vehicle's alternators with heavy-duty upgrades to accommodate big power demands.

Q: Where should I ground my amp?

A: Your ground wire should be of the same gauge as your power wire and must make direct contact with the body of the car. Look for an existing bolt or screw that makes contact with the car body near the amp. Remove the bolt or screw, and scrape away any paint or grime.

A star washer will help your ground wire maintain solid contact with the car body. Use a ring terminal on the end of the ground wire, to keep it securely fastened to the bolt or screw.

If you can't find a convenient ground screw or bolt, drill a hole for one. Be careful not to drill into the gas tank, a gas line, or a brake line.

If you're grounding multiple components, try to ground each one separately, with about a half-inch of space between each of the grounding points. If you'd rather use a single bolt, place the ground for the most current-hungry component (probably the biggest amp) closest to the body of the car. Put the ground for the component that draws the least current (probably the electronic crossover) on top.

Q: What is a "high-current" amplifier?

A: A "high-current" amplifier is a high-performance amp capable of passing high current into very low impedances without overheating or shutting down. In a perfect world with a perfect amplifier, power output would double every time the impedance was halved. For example, an amplifier rated at 50 watts RMS x 2 channels into 4 ohms would produce 100 watts by 2 into 2 ohms. Unfortunately, this is not a perfect world, and most amplifiers can't do that.

The best way to identify a high-current amplifier is to look at what happens to the power rating as the impedance drops. The closer it comes to achieving the perfect world scenario above, the more current it is capable of passing.

Q: How much power do I need for my subwoofers?

A: That depends on what sort of bass impact you hope to achieve. If you just want to hear a bit more bass than your regular stereo speakers can put out, you can get what you need with an efficient 6-1/2" subwoofer driven by as little as 30 watts RMS. But when you're looking for really big bass, you'll need at least a 10" or 12" subwoofer and a minimum of 150 to 200 watts to drive it. Low bass notes are power hungry, and the more wattage you feed them, the better they sound. In general, the larger your subwoofer and the harder you want it to hit, the more power you'll need.

Remember, if you're driving one sub, you can "bridge" a 2-channel amp to get a significant increase in output. Our individual product descriptions list bridged output for each of our amplifiers. You also may want to take a look at our selection of Mono Subwoofer Amps, since their features and design are specifically tailored for the job of driving low frequencies.

We usually recommend that you drive your speakers/subwoofers with at least 70% (70-100%) of their maximum RMS (not peak) rating to get them to perform at their optimum. The closer to 100% you power them, the harder they hit and the better they sound.

Q: What should I know about my speakers' impedance?

A: Impedance is the load value that your speakers present to your power source — the amount of resistance they provide to the current flowing from your amplifier. While it's convenient to refer to a speaker's impedance as being a fixed value (say, 4 ohms) over a speaker's entire frequency range, the impedance typically varies with the frequency of the input signal. So when we say a speaker is a 4-ohm speaker, think of this rating as a useful approximation.

The key things to know about impedance are your speakers' ratings, your amplifier's ratings, and whether they match. That's enough to keep you out of trouble, and even let you get a little creative when you're designing your system.

In the car audio world, the typical stereo amplifier is stable down to 2 ohms in stereo, or 4 ohms in mono (or "bridged") operation. Most car audio speakers are rated at 4 ohms, but 2-ohm, 8-ohm, and dual voice coil subwoofers are increasingly common. Car audiophiles know that they can actually make their systems hit harder by combining higher-impedance woofers.

Bridging a stereo amplifier down to a single channel is a great way to maximize power to a single speaker. You could use this single channel to drive a single 4-ohm woofer. But some fans of aggressive bass prefer to hook up two parallel-wired 8-ohm woofers — the subwoofers' total impedance remains the same but the overall surface area is increased, raising the system's sound pressure level. If you've invested in an amplifier that's stable down to 2-ohm mono (1-ohm stereo), you can further raise the stakes in this game by introducing up to four parallel-wired woofers to your bridged amp. You'll get more bass from the increased surface area, and more power output as well.

But before you rush out to run your car audio amplifier at the minimum impedance it can handle, bear in mind that there are trade-offs involved. As you decrease the impedance your amplifier sees, the amplifier's distortion spec will rise. On the other hand, some people claim that, in the hard-thumping arena of car audio subwoofers, such changes are inaudible and insignificant.

So what's the bottom line? Make sure you know your speakers' impedance ratings, as well as the minimum impedance of your amplifier in bridged and stereo modes. Then experiment carefully and go with what sounds right.

Q: How can I drive a pair of speakers and a subwoofer with a single car audio amplifier?

A: One of the keys to getting the most out of your audio investment is choosing gear that will go to work for you now, and won't become obsolete as your system grows. Most car audio amplifiers boast a design flexible enough to keep them in the game as your set-up expands.

If you go with a 4-channel amplifier, powering a pair of front speakers and a subwoofer is a breeze. You'll simply want to run your amp in what we call "true" 3-channel mode. To do this, bridge the rear channels to power your subwoofer, while the front channels drive the pair of regular stereo speakers. Bridging the rear channels means combining them in mono mode to create a single channel. Choose an amp that lets you engage a built-in, low-pass filter on this bridged channel. The crossover, along with the increased output from the mono channel, makes this an ideal way to power your sub.

As your system grows, you may dedicate a separate amplifier to your sub. At that time, you could add another pair of stereo speakers for rear fill, and run your 4-channel amp in stereo mode.

But what if you're starting out with just a simple two-channel amp and you still want to power a pair of stereo speakers and a sub? No problem. That's where a feature known as "Tri-way mode" (or "Tri-Mode") kicks in. You'll notice that virtually all the amplifiers on our website and in our catalog are described as "Tri-way capable." That means you can attach a Tri-way crossover to a pair of stereo amplifier channels to produce three channels — two stereo channels for front speakers, and one mixed-mono channel for your sub.

The Tri-way crossover is actually a special kind of passive crossover network. It applies a high-pass filter (typically at around 100 Hz) to each of your amplifier's stereo channels, sending the information above the crossover point straight to your stereo speakers. It also combines the low-frequency information from each of these channels into a single, mixed mono channel, which is sent to your sub. As is the case when you bridge an amplifier, the mono channel delivers more output than the stereo pair.

If you're about to purchase an amplifier, you'll get the most value by purchasing one that can run in true 3-channel mode. If your goal is to eventually own a high-performance "audiophile" car audio system, you'll want the performance and features that these amps typically provide. You'll be able to adjust the volume of the sub, and in most cases, the frequency of a built-in electronic crossover, as well. You give up these conveniences when you go Tri-way.

But while Tri-way mode doesn't give you the degree of control or performance that a true 3-channel system provides, it is an affordable, effective way to get the most out of a budget system built around a single amp. And because Tri-way crossovers are relatively inexpensive, if you decide to add more amplifiers and reconfigure your system later on, you won't be out a huge investment.

Q: My new car amplifier is "2-ohm stable." How can I take advantage of that?

A:Typically, a car stereo amp "sees" a 4-ohm impedance. When we say an amplifier is stable down to 2 ohms, we're usually referring to the minimum impedance it can handle in stereo (2-channel) mode, not bridged (mono) mode. The lower the impedance (resistance or "load") an amplifier sees, the more power it produces, and the louder your music plays.

A common way to get a 2-ohm stable amp to produce the extra power it delivers at lower impedance is to wire your speakers in parallel. While series wiring always raises your impedance, parallel wiring always lowers it. See below for instructions on parallel wiring. For example, you can dramatically increase your system's impact by hooking up not one but two subwoofers in parallel to each of your amp's channels. Or, if you're looking to max out your 2-ohm stable amp's muscle with only a single pair of hard-hitting drivers, consider our dual 4-ohm voice coil subwoofers.

Q: What's the story on the different amplifier "classes"?

A: An amplifier's circuit design determines its class of operation. Class A amplifiers are desirable for the high quality of their sound, but the design is not particularly suited to car applications because of inefficiency and high heat production. Car amplifiers that boast Class A design are usually a Class A/Class AB hybrids. The Class AB design is most commonly used for car amplifiers because it combines reasonable efficiency, low distortion, and reliability.

Class D amplifiers ("D" does not stand for "digital") boast higher efficiency, produce less heat, and draw less current than traditional Class AB designs, but they tend to have more distortion. Since low-frequency distortion is almost impossible to detect, compact Class D amps rule the bass kingdom. Class T amplifiers combine characteristics of conventional Class AB and cutting-edge Class D designs for great power, compact size, and minimal production of heat. For more information, check out "Classes of Amplifier" in our Amplifier Glossary article.

Q: What's the difference between "parallel" and "series" wiring?

A: When you wire a pair of speakers in parallel, you connect the positive (+) leads of both speakers to the amp's positive (+) terminal and the negative (-) leads of both speakers to the amp's negative (-) terminal.

If you parallel wire two 4-ohm speakers, the amp sees a 2-ohm load. This lower ohm load (lower resistance) pulls more power from the amp and causes the amp to run hotter. Amps that can handle this additional heat build-up are considered 2-ohm stable.

Series wiring works the same way as flashlight batteries; the positive end of one speaker is connected to the negative end of the other speaker. Wire from the positive terminal of the amplifier to the positive terminal of one speaker. Then wire from the negative terminal of the first speaker to the positive terminal of the second speaker. Finally, run a wire from the negative terminal of the second speaker to the negative terminal of the amplifier.

If you series-wire two 4-ohm speakers, the amp will see an 8-ohm load. This higher ohm load (higher resistance) inhibits the flow of current out of the amp. You get less power, but the amp runs cooler and is more stable.

You can run more than one speaker from a single amp channel by wiring the speakers in series or in parallel. Series wiring will raise the load (resistance) that your amp sees, and parallel wiring will lower it. Be certain your amp is 2-ohm stable before wiring speakers in parallel.
Q: When should I use a mono amplifier instead of a multichannel amplifier?

A: Because mono amps tend to be Class D amplifiers, they are a good choice for powering subwoofers — Class D amplifiers have a high power-to-heat ratio and excellent efficiency, which are exactly what you want when dealing with power-hungry low frequency signals.

Most mono amplifiers are designed to run at 2 ohms; some are even 1-ohm stable. Multichannel amplifiers, on the other hand, are typically designed to work with a 4-ohm load. This is an important difference when using your amp to power multiple subwoofers, because you won't be able to bridge your multichannel, 4-ohm stable amp to power multiple subs that present less than a 4-ohm load. Instead, use a mono amplifier to power a 2-ohm load — two 4-ohm subwoofers, or 2, 2-ohm dual voice coil subwoofers, for example. You'll be able to push your subwoofers with the mono amp's maximum power, without running at a dangerous impedance.

Q: What are the benefits of hooking up 2 subwoofers to a mono amplifier? How would I wire them?

A: The benefits of hooking up two subs to a mono amplifier are the same as hooking up any other number of subs to a mono amp: you can push the subs with more power at lower impedances. Because lower frequencies are less directional (i.e. it's more difficult for your ears to determine where low frequencies come from than highs), bass is often transmitted in mono. Mono here refers to a single channel (as opposed to stereo, or two channels), not one speaker.

Most mono amps have two sets of speaker terminals for convenience of installation: if you are hooking up two subs to the amp and using large-gauge wire, it gives you a place to attach the wires without having to trim them, appearing as if each subwoofer gets its own terminal. But in reality, these terminals are actually tied together inside the amp &span; both positives are going to the same place inside the amp, as are both negatives. If you are using more than two subs, then you simply use parallel or series wiring (or a combination) to get as close to the minimum impedance of the amp as possible (see our subwoofer wiring diagrams for more information).

Q: Can I bridge my mono amplifier?

A: No, you can not bridge a mono amp because there is nothing to "bridge" to — whatever impedance load you present to amplifier is the actual load that it sees. This differs from a multichannel amp in that when you bridge two channels together, you halve the load presented to them (for example, 2 4-ohm woofers wired in parallel and bridged to a stereo amplifier is "seen" as a 1-ohm load to that amp).

Q: I'd like to add a power amplifier to my factory-installed car radio. What are my options?

A: Because it's a great way to increase musical detail, dynamic range, and volume, adding a power amplifier is an extremely popular factory system upgrade. And when the weather gets warm, even more people tell us they're looking for a system that can deliver roll-down-the-windows volume.

But your factory radio poses a challenge. It usually doesn't offer preamp outputs. So how will you hook up to the preamp level inputs found on the typical aftermarket amplifier? The easiest way around this roadblock is to choose an amplifier with speaker-level inputs.

Speaker-level inputs let you use your factory speaker wire to feed an amplifier the musical signal from your radio. You won't need an RCA patch cable or a receiver with preamp outputs. But if the amplifier that really appeals to you doesn't have speaker-level inputs, don't sweat it. You can use an RCA patch cord with an inexpensive line output converter and still get signal from your factory speaker wire.

In addition to connections for power and ground, any speaker-level amp hook-up requires you to tap into the factory speaker wire. Make the connection with aftermarket speaker wire you run to your amp (or line-level adaptor). In most vehicles, the easiest place to access the factory speaker wire is from the trunk, where it connects to rear speakers below the deck.

If your vehicle doesn't have a trunk, you'll want to connect to the factory speaker wire behind your radio. When you get your gear from Crutchfield, you'll have access to our exclusive toll-free Technical Support. Our experts will help you identify the correct wires.

When you're ready to actually connect the new speaker wire to the factory speaker wire, strip back the insulation on the factory cable, without cutting the actual wire. (A quality wire stripper makes this type of careful cutting easy.) Then, wrap the stripped-back aftermarket speaker wire around the exposed factory strands. Solder for the best possible connection, then cover with electrical tape.

Well there you have it — the "nitty as well as the gritty". Remember, this is a relatively simple installation, and definitely one of the best ways to fill your car with truly dynamic sound.

Q: How do I fine-tune my amplifier's gain and bass boost settings?

A: Setting the "gain" or input sensitivity control is an important adjustment common to all amplifier installations. Proper gain setting helps reduce noise and distortion and allows for the widest possible dynamic range. Here's how to do it:

Turn your amplifier's input level controls all the way down.
Put in a tape or CD or tune in a radio station. Turn up your receiver's volume control. You'll begin to hear music at faint levels. (Audiophiles and sound competitors may want to use a dedicated test disc.
When you start hearing distortion, lower your receiver's volume control until the distortion disappears. At this point, you have as much signal as possible passing from your receiver into your amp. (This gives you maximum signal-to-noise ratio, so you'll enjoy clean sound and your system will be less prone to engine noise problems).
Now begin adjusting your amp's input gain. Turn the input level controls up until the system is as loud as you can stand it or until you begin hearing distortion — whichever comes first. If you hear distortion, decrease the gain settings slightly.
By following this procedure, you'll optimize your amp's performance at the receiver's maximum volume level, so you can crank your system almost all the way up without amplifying any distortion, or damaging your speakers. Keep in mind that this adjustment does not affect the power output of the amp — you're simply setting the amount of input signal needed for optimum sound quality from your system.

Car stereo competitors sometimes employ a technique called "gain overlap" to wring some more dBs out of their rigs while keeping distortion out of the audible range. Many amplifiers have a bass boost function. In most cases, it is a variable control — you simply dial in the amount of boost you'd like to hear. Bass boost levels can range from +6dB to +18dB, depending on the amplifier. As you experiment with this adjustment, you'll notice that the boost is centered at a given frequency, so you'll still experience some bass boosting at frequencies above and below that point. Make sure that your system is turned off or operating at low volumes when you engage or turn up your bass boost control — boosting bass at high volumes can damage your speakers.