Car Audio Show Competition Organizations

Car audio shows are one of the most exciting things in the car audio hobby. They bring together people of all backgrounds that share a common love for car audio and competition. There are four major car audio show competition organizations. If you think competing is right for you, check them out below. Not all car audio show organizations are available in all areas.

IASCA - The oldest car audio competition organization and also the largest. IASCA has traditionally been associated with sound quality competitions but has more recently added the idBL, an SPL (boom car) category. Their sound quality segment, SQ, has seven categories and only two power classes, 1-600 watts and 601+ watts.

USACi - Once the new kid on the block, USACi has become a major player in the sound off scene. USACi also has two competition formats, SQ (sound quality, basic and advanced categories) and SPL (boom car). USAC was started with the idea of bringing fun back into car audio competitions. There are two power classes in each SQ division (0-600, 600+) and several in the SPL competitions.

dB Drag Racing - Started and led by veteran competitor and soundoff legend Wayne Harris, dB Drag Racing is just what the name implies. Competitors boomin side by side for the title of loudest vehicle. The measurements are displayed on a large drag racing type "tree" and are very exciting to watch. dB Drag is all about SPL. If you want to be a boomer than you need to look into dB Drag Racing. Competitors are classified by the number of woofers in their system and the extent to which their vehicle has been modified.

MECA - MECA classes its SQ competitors by the extent of vehicle modification. Competitors are classed as either Amateur, Street, Modified, Modex or Extreme. MECA also offers SPL classes in similar categories.

Choosing a Quality Amplifier

Also keep in mind the quality of the amplifier. A generally good indication of quality build and the power output is the size and the weight of the amplifier itself. Better quality amplifiers will usually have a heavier and larger heatsink versus a low quality amplifier of the same power rating. Do not accept size as a definite indication though. I bought an amplifier at a yard sale for two dollars that was two feet long, eight inches wide and two inches tall that had a five inch square circuit board inside of it. This amplifier was so poorly built that I could actually hear the music I was playing coming from the circuit board itself. However there are many top quality amplifiers that do not follow this rule. The ever growing Class D (and its variants) amplifier is much more efficient and there does not produce as much heat or use as much power. This means a smaller power supply and a smaller heatsink. Because of the high efficiency design of those amplifiers a heavy heatsink is not required.

Also a good indication of an amplifier's true output is the size of the fuse used. True two hundred watt amplifiers do not use a ten amp fuse. Use your head when buying and keep in mind the brand's reputation for quality. A quick and dirty way to check the true power output of an amplifier is to take the fuse value of the amplifier (or the sum for multiple fuses) and multiply it by 6 for class A/B amps or 10 for class D amps (higher efficiency). This is by no means an accurate way to judge power but it will tell you if your amp is even close to it's specifications. For example, if a class A/B "1,200 watt" amplifier has a fuse value of 25 amps then you can take 25*6 and get 150. So this "1,200 watt" amplifier is more in the range of 150 watts.

If you find yourself on a budget or lack space for many components then the economical thing to do is buy a multi-channel amplifier with the built in features and processors that you desire. This can save a lot of room and several hundred dollars in added component and installation cost. The quality will be a little less as compared to outboard processors but will probably not be noticed. Also, by minimizing the number of components the chance of noise entering into the system is lessened.

Some features and aspects of amplifiers to consider are:

Bridgeable: This feature allows a pair of amplifier power channels to be combined into one channel of greater power. This is usually used for driving a subwoofer although it will work with any other type of speaker as well.

Channels: A channel is one power (speaker) output of an amplifier. The more channels an amplifier has the greater the installation flexibility it will have. Especially in terms of options, future add-ons and upgrades.

Class: This refers to the way the amplifier operates. The three types that are most likely to be encountered are A, A/B, and D. Class A amplifiers are the least efficient in terms of power consumption, staying on continually, but also have better sound in general than A/B amplifiers. They are very, very rare in car audio. Some argue non-existent but in any case don't expect to see any. Class A/B amplifiers are more efficient than the class A design and are the most common type. Almost all amplifiers in the car audio market are of the A/B design. Class D amplifiers are usually reserved for high power subwoofer amplifiers and can reach efficiencies in the 80%+ range. This design can therefore be smaller, uses less current and produces less heat than the other classes. However there are some full range Class D amplifiers becoming available.

Connectors: This is the method of attachment used for wires that are connected to the amplifier, including speaker and power wires. The most common kind is the screw terminal strip. This is a series of screw connectors that can be removed and replaced without compromising the amplifier. The other main type of attachment is the "Molex" type connector. This method involves a wire harness that plugs into the amplifier after the power and speaker connections have been made with a crimp or solder connection. If the amplifier is installed in more than one system these wires can get pretty short over time and become more difficult and even dangerous to work with. A variation on the two is a harness that the power and speaker wires screw into. Then the harness plugs into the amplifier. This is probably the most convenient of all connections. Virtually all amplifiers use the screw terminal strip though many older amplifiers used the Molex or straight wire connections.

Crossover/Filter: A built in crossover can be useful, especially if it is many frequencies of adjustment. A filter is a crossover that only affects one channel, not actually splitting frequencies but simply reducing a range of them. Most amplifiers that have built in filters will have the option for either Low Pass (LP) or High Pass (HP). If you see AP on the filter that means "all pass" which basically means the filter is turned off and passes all frequencies.

Distortion: This is often given as T.H.D. or total harmonic distortion. It is the measure of how much an amplifier will change a signal from the input signal it is given. Figures below 0.1% are negligible and will probably not be heard. Usually the figure can be in the 3% range without being heard but virtually all high quality amplifiers will have a T.H.D. below 0.1%.

Efficiency: This is the ratio of of power input (from the battery) to power output (to the speakers). A 100 watt amplifier with an efficiency of 50% would take in 200 watts of power from the battery and output 100 watts of power to the speakers. The other 100 watts of power would be wasted as heat. The higher the efficiency of an amplifier the better. Most class A/B amplifiers are around 50-60% efficient and Class D around 80%. Amplifiers are generally less efficient at low power and more efficient at full power so this number varies in actual use.

Power Output: The rated power output of an amplifier should be given into a four ohm load, all channels driven from twenty to twenty thousand hertz (20Hz-20kHz). Keep in mind that while the low end amplifiers are exaggerated in their power output, many high end amplifiers are under-rated in their power output. These are sometimes called "cheater amps" because they allow a car audio competitor to compete in a lower power class while in reality having a larger amplifier. This under-rating may be three times less than the actual power output. Look for the CEA 2006 standard when comparing amplifier power.

Power Supply: The two most common types are the IC chip and the MOSFET supply. The IC chip is what is used in most source units (head units) and are only capable of producing about eighteen watts per channel. MOSFET is the more common design and has a smoother sound than the chip design.

Pre-amp Inputs: This is a set of jacks (usuallyRCA Jacks) that will accept a low level pre-amp signal from a source or processing unit.

Pre-amp Outputs: This is a set of jacks (usually RCA Jacks) that pass on a low level pre-amp signal to another amplifier or processing unit. These will sometimes be filtered outputs.

Separate Gain Controls: This allows the gain of each channel of the amplifier to be set independently of the other(s). This allows you to more evenly match the amplifiers channels.

Speaker Level Inputs: For source units that do not have pre-amp level RCA outputs this feature may be used to take the signal from the speaker leads of the source unit. The signal will not be as clean as a pre-amp level output but will be adequate for most factory upgrade applications.

Stability: The measure of how low of an impedance load an amplifier can handle (in ohms). Any good quality amplifier will be two ohm stable while a rare few will go as low as a quarter of an ohm. Ideally an amplifier should double its power each time the load is halved. For example, a one hundred watt amplifier (into a four ohm load) should produce two hundred watts into a two ohm load and so on. This is most useful when running multiple speakers off of a single amplifier or in sound off competitions that are classed by total power output.

Tri-Mode Output: This feature is available under different names but is the ability of an amplifier to run a stereo pair of speakers and a mono subwoofer (or center channel) from only two channels of the amplifier. Personally, I would not recommend doing this. Instead buy a good quality four channel amplifier and bridge two of the channels for the subwoofer.

Tube Amplifiers: These are the least common amplifiers and are also the most expensive. Rather than the traditional solid state components they use old fashioned vacuum tubes. They are said to produce a warmer sound and a smoother midrange than solid state designs. For most systems the standard design will be more desirable.

What Is Sound?

Sound?
Webster's dictionary defines sound as:

"The perceived object occasioned by the impulse or vibration of a material substance affecting the ear; a sensation or perception of the mind received through the ear, and produced by the impulse or vibration of the air or other medium with which the ear is in contact; the effect of an impression made on the organs of hearing by an impulse or vibration of the air caused by a collision of bodies, or by other means; noise; report; as, the sound of a drum; the sound of the human voice; a horrid sound; a charming sound; a sharp, high, or shrill sound."

Mmm, fancy. We all know what a sound is. It's a noise, something we sense with our ears. But what is sound? It's the vibration of the air by a moving body. For our purposes in car audio that moving body is our speakers. The movement of the speaker forward and backward causes a vibration in the air that our ear receives and we hear music. Here's what sound looks like as a wave:



 
A sound wave goes through a cycle of 360 degrees. As the speaker moves forward it goes from rest (0 degrees) through one quarter of its cycle to 90 degrees. As it starts to move back to rest it travels another 90 degrees to the 180 degree mark before moving completely rearward to 270 degrees. As it moves back to the rest position it travels the final 90 degrees to the 360 degree mark. The cycle then repeats itself and we hear the result as music. To summarize, as the speaker moves up and down it travels one cycle which equals 360 degrees. These cycles are measured in Hertz (Hz) with one Hertz being equal to one cycle. The lower the number of Hz the lower the sound we hear. A human can hear, on average, the sounds between 20 Hz and 20,000 Hz (also known as 20 kHz).

We do not hear all of the sounds equally though. Our ears are less sensitive to sounds at the far ends of the scale. This was discovered through research done by Fletcher and Munson and they have given us the "Fletcher-Munson" curve which illustrates this point.



Notice how the curve goes up at both ends of the scale. Also notice how the curve is greater at lower volume levels (sound pressure levels). This is what the loudness circuit on a head unit tries to do. Increase the level of the low and high frequencies at lower volume levels. As the volume goes up the level of boost at these frequencies is reduced. However, some loudness circuits do nothing more than boost the low and high frequencies by a constant amount. If you've seen a vehicle with an in-dash equalizer the chances are very good that the vertical sliders were arranged in a similar fashion to the Fletcher-Munson curve. This is sometimes called "making your EQ smile".

Types of Audio Power

Car Audio Power Capacitors
Power capacitors or Stiffening capacitors are used to assist an automobile that has a problem with dimming lights (voltage sag) or to help tighten up the bass. These capacitors store a large amount of power and then release it very quickly when the demand is the greatest from the amplifier. These capacitors release the current much faster than a battery can and do not force the amplifier's power supply to be at a loss (due to a voltage drop) when bass notes and other transients are greatest. Capacitors should be chosen in the ratio of one Farad per thousand watts. Click Here to see how a power capacitor is wired in a car audio system.

Car Audio Batteries
If extended engine off listening is desired then a second battery can be useful. Keep in mind that this will put a greater strain on your charging system as well as add several hundred dollars for a second battery, dual battery isolator, and installation charges (or headaches for the DIY'er). If you are having problems with your charging system then you might need a new or larger alternator. Have it checked out by a qualified technician.

Features and terms that may be encountered with regard to wiring are:
Butt Terminals: This type of terminal resembles a long barrel and is used to connect small gauge wires together. These type are crimp terminals and considered less desirable than soldering when soldering is an option. These terminals are also sometimes referred to as crimp connectors though that term can apply to many variations of crimp terminal.
Deep Cycle: A battery usually reserved for marine use that can be drained and replenished many times. While popular years ago many installers have relegated this battery to system use only with a traditional car battery for main power.
Farad (F): The base unit of measure for capacitor storage. One farad is very larger and is equivalent to one million microfarads (uF).
Gauge: This refers to the diameter of the wire. The smaller the number, the larger the wire. Sixteen is common for speaker wire, eight is common for average size amplifiers, while four gauge and below is used for large amplifiers. For reference, four gauge wire is about the same diameter as the average male pinky finger.
Gel Cell: A type of battery that uses a gel type acid. These batteries can be desirable because they may be mounted upside down without the danger a standard type battery would pose.
Heat Shrink Tubing: A type of insulating plastic that resembles a drinking straw. A small portion of this tube is cut off and placed on a wire before soldering. After the connection is soldered and cooled, the tube is slid over the joint and shrunk around the wires by means of a heat gun or hot hair dryer.
Microfarads (uF): The more common unit used to measure capacitor storage. One million microfarads is equivalent to one Farad.
OFC: An abbreviation for oxygen free copper. This is the most desirable wire to buy and there is really no reason to buy any other kind. As the name implies it is pure copper that is free from oxygen impurities.
Spade Terminals: A type of terminal used on most speakers. The type found on speakers are male spades while the ones used to connect to these terminals are female spades. These terminals are also referred to as quick disconnects though this name can apply to many different types of terminals that come apart quickly.
Voltage Rating: Referring to the amount of voltage a capacitor is rated to handle. The very least a capacitor used for reinforcement should be rated at is 16 volts while 20 volts is much more desirable and available on the slightly more expensive capacitors.

Installing a subwoofer in a pre-fabricated enclosure

This guide will cover the installation of one or more subwoofers in a pre-fabricated enclosure. It will also cover the process of hooking up an amp to power the sub.

The easiest way to add low-end punch to your car’s stereo is to install a subwoofer. This guide will cover the installation of one or more subwoofers in a pre-fabricated enclosure. It will also cover the process of hooking up an amp to power the sub.


The first thing to do is to put the woofer into the box. This should be easy as long as you got the right size enclosure. Before actually screwing down the speaker, be sure to connect the included leads to the terminal in the back of the box. Next, screw the woofer down tight into the front of the box and mount the protective grille directly over the speaker.

Put the box in the trunk. For the best sound, the woofer should be facing the back of the car. To keep it from sliding around, consider using high-strength Velcro strips to secure it to the trunk floor. If this is not possible, L-brackets may be mounted to the cargo floor, but be sure not to put any screws through the side of the box. However you decide to secure it, make sure that it is out of the way of anything you put in the trunk.
Now it is time to install the amplifier. Begin by mounting the unit in the desired location. This should be a flat area with a lot of open space so that the amplifier can cool properly. Do not mount the amplifier on the subwoofer enclosure, as the vibrations from the speaker can damage the internal parts.

The next step is to hook the amp up to power. Before doing this, disconnect the negative terminal from the battery. Hook the long positive power cable for the amp to the positive terminal of the battery. If the cable does not have a fuse, you should install one inline within three feet of the battery connection. Consult the amplifier owner’s manual for the size of the fuse. Run the fused positive cable through the firewall and back into the cabin. Remove any trim panels necessary and pull back the carpet so you can run the cable underneath. Once the cable can reach the amp, trim off any excess, strip the end, and connect it to the positive power terminal of the amplifier. For the negative cable, connect it first to the amplifier, then run it beneath the cargo floor of the trunk and connect it to a ground point on the chassis or floor pan.
Next, you need to connect the amplifier to the head unit. You should do this using the subwoofer pre-amp hookup on your stereo. This can be either a stereo (paired RCA plugs) or mono (single RCA plug) connection. Unless you have a mono subwoofer amp, you will need to use a paired RCA cable to plug into the amp. If your head unit has a mono RCA out, this means you will need to use an RCA mono-to-stereo adapter to plug the stereo cable into the mono jack. Run the RCA cable underneath the carpet on the opposite side of the car from the power lines to avoid interference. When you get the cables back to the amplifier, plug them in at the RCA in terminals. Before putting the carpet and trim back, run a small 16-18 gauge wire from the head unit amp remote connection to the remote control terminal on the amplifier. At this point you can replace the carpet and trim panels to make the installation look clean.

The last step is to plug the subwoofer into the amplifier. To do this, use 12-14 gauge speaker wire. If you have a bridgeable stereo amp, you should bridge the amp by plugging the positive wire into the positive terminal for the left output and the negative wire into the negative terminal of the right output. The actual configuration of the bridge will vary from amp to amp, so read the owners manual for specific instructions. If you have a mono amp, simply connect the positive and negative wires. Finally, plug the wires into the back of the sub. If you have more than one sub, you can run a length of stereo from one sub terminal to the other.
Finally, put the negative terminal back on the battery and fire up your system. You will need to adjust the gain and filters on your amp, if it has them. First, turn on the low pass filter (LPF) option. Then, turn the gain all the way down. Turn up your stereo until the speakers begin to distort, then turn it down just a hair until it no longer distorts. With the stereo playing at this volume, turn up the gain on the amp just until the subwoofer begins to distort. At this point, turn the gain down a bit. That’s it; you’re done, and good luck with your new subwoofer.

Amplifier Troubleshooting

Please try these things before sending in your amplifier. By the numbers, 40% of all amps returned to us work just fine and there is a problem in the wiring or install.
You must have a DMM (Digital Muti Meter) and know how to use it.
If no: take it to someone who does.
If yes: thumb through the following scenarios

Amp will not come on (no lights):

Set DMM to DC voltage and check at the amp. You need to test with both (+ & -) leads on the amplifier Power terminals.

If over 12 volts: check both sides of the fuses in the amp.
If no or low voltage: ground the DMM (-) test lead to a good, clean, metal chassis ground in the vehicle and retest.

If over 12 volts now: problem is in the ground wire or connection (between the amplifier and its chassis ground).

If still no voltage: check both sides of the fuse by the battery.

NOTE: You cannot check a fuse by just looking. Fuses can be “bad” and not blown; especially the larger, cheap-ass, glass ones.

If blown or bad: replace and start beatin’ again!

If all is good with battery voltage, it is now time to check the remote (or turn on) wire. Check voltage at terminal of amp.

If no voltage: check voltage at head unit. You can also make a jumper from the main 12V+ connection to the remote terminal to see if the amp comes on. If it does, the problem is in the head unit remote output or remote wire between the head unit and the amplifier.

If all power wiring tests good, remove the amp from the vehicle and test with short jumper wires directly at the battery, using a jumper wire from amp 12V+ to the remote terminal, just as a “I need to make sure” final test. If it still doesn’t come on, it needs to be sent in.

Amp turns on but goes into protect:

Disconnect RCAs and speakers and try turning the amp on again.

If it still goes into protect with just power, ground and remote; the amp is bad.

If it is now on and not in protect: connect the RCA’s first.
If it goes into protect: the problem is in the cables or headunit. Change and retest.

If still not in protect: reconnect speakers
If it goes into protect: problem is in the speakers or wiring (most likely shorted [or grounded] wiring or burnt coils). Set DMM to 'ohms' and first test by shorting leads together. This number (usually in the .4 range) will be subtracted from any reading you get. Connect DMM leads to each speaker wire pair. If you have a short, reading same as touching the leads together, trace the wiring to find short.

If no short in wiring: test the speakers individually and eliminate problem.

If amp comes on (and not in protect) and has no output:

Check all settings. Turn deck on at low volume.
       Master/Slave switch in master position.
       Gain all the way up.
       Subsonic filter all the way down.
       Boost all the way down.
       X-over all the way up.

If still no sound: you will need to try an alternate input. The best is a signal generator right to the input of the amp. Alternately, you could use another radio wired in with temporary wiring right at the amp with a very short, known-working RCA cord.

If still no sound: try a known-working test speaker with very short wiring right to the amp terminals. If still no sound: amp is bad. This is a very rare failure but it can happen.

Amp has distorted output:

Same test as above. You need to eliminate all the variables.

If you are testing a stereo amp and you have the problem on one channel:

Swap RCA’s: if it changes sides, the problem is in the deck or RCA cables.

If same side: swap speaker outputs at the amp. If it changes sides, the problem is in the amp. If it stays on the same side, the problem is in the wiring or speaker.

Amp plays but has low output:

Check all settings. Turn deck on at low volume.
       Master/Slave switch in master position.
       Gain all the way up.
       Subsonic filter all the way down.
       Boost all the way down.
       X-over all the way up.

Turn up the radio. If problem remains:

Check voltage drop at amp power input terminals. Set your meter to DC voltage with the hold feature activated. If your meter does not have that feature you will need to watch it to see how low the voltage drops when it is trying to play loud. If voltage drops below 11 volts at any time, you need more battery/alternator power and or better wiring.

If voltage remains above 12 the entire time, you need to check the speakers.

Set meter to ohms and check the DC resistance of the speaker load. If it falls within the proper load for the amp, check the amp, hooked to known-working speakers. If new speakers work, the problem is in the speaker system. If it still has low output, you need to check the inputs as described above with a known-working deck and RCAs.

Amp plays but cuts off and on:

Attach volt meter to power and ground terminals at the amplifier.

Set the meter to peak hold (max/min) and display "minimum DC voltage".

Run the system until the amp shuts off and check the voltage. If voltage has dropped below 10 volts at any time, check all wiring.

Leave the meter positive on the battery wire and use a good, clean ground point on the vehicle and test again. If voltage has a higher reading than before, the problem is in the ground connection.

If it has the same voltage, work your way back to the battery; testing at any and all connection points. I.e. distribution blocks, capacitor, fuses, etc.

If at any point voltage goes up, you have found the voltage drop point.

Single vs. Multiple Drivers

There are advantages and disadvantages to either approach. For this, let's consider a scenario where the cone area of a single driver is equal to the cumulative cone area of multiple drivers: An example of this would be a single 10" woofer with an Sd of 50in^2 versus a pair of 8" woofers with an Sd of 25in^2 each.

The single driver advantage: Linearity. A single driver system isn't subject to the acoustic or electrical forces countering in phase--even if by a fraction of a degree--which typically occurs when multiple pistons share a common space or when multiple inductors share a common circuit.

The single driver disadvantage: It has been my observation that a single larger driver will typically exhibit higher equivalent air compliance (Vas) than the combined compliance of two smaller drivers. This can translate into higher Vb requirements.

The multiple driver advantage: Assuming that the motor structure is the same on both the 8" and the 10" model, the immediate advantage is twice the motor for every square inch of cone area, twice the power handling, and more end-impedance versatility.

The multiple driver disadvantage: As stated above, using multiple independently actuated pistons increases the risk of the electro-mechanical forces countering one another. This is particularly evident with high Qts drivers.

The Perfect Subwoofer Box

We often hear talk (specially in car audio) about certain boxes being RIGHT for certain woofers. Many folks talk like a given woofer wont even play at all if the box size is not exactly perfect!

What is perfect?

Manufacturers often recommend a certain box for their speakers.

Computer box programs can PICK the box size (or tuning) that works best(?) with the woofer if you input the Thiele/Small parameters.

Is the box size the manufacturer recommends perfect? How can it possibly be perfect when they don't even know what kind of car your installing the box into? We all know the car will change the sound (this is called transfer function)! How can they possibly choose the perfect box size? Many times the speaker manufacturers recommendation is chosen not for perfect sound but for an average that might work well in the average car. Many times they might recommend the box that's easiest to build for beginners or small (since many folks like woofs that work in small boxes) or sealed instead of vented because it is less likely for you to blow your speaker in a small sealed box than a large vented box! (if you blow your speaker (a) they might have to replace it. (b) the company might get a reputation for lousy speakers if they blow a lot) Sure, the manufacturers recommendation will probably sound great! But perfect??? Is the manufacturers recommended box size really right for you?

Is the box size provided by computer programs perfect? Again, how can it be unless they take into account the transfer function of the car??? I don't know of a current popular program that does! Most computer programs will calculate a box for you with the lowest response and with the least ripple. In car audio, this many times IS NOT the best! Sometimes (specially in SPL competitions) the ripple the computer program tries to avoid might actually be an SPL or bass boost! Or for an SQ car, a slight ripple (inaudible, an may likely be made up for by the cars transfer function) might get you much deeper bass... Is the computers recommendation the perfect box? Is the computer programs recommended box right for you?

How bout the difference in CUSTOM made boxes vs PREFAB boxes?

Most real car audio enthusiasts would never consider a PREFAB box, we all know the custom built boxes are far superior sounding... BUT ARE THEY REALLY?

From my experience there is a great amount of BADLY BUILT custom boxes being built! Built so badly in fact that for many cases a prefab box would be miles better!

A prefab box could be better than a badly built custom box! I have heard some darned good systems with prefab boxes and some very poor systems with custom built boxes.. It's important if your gonna pay high dollar for an installer to build you a custom box that the installer be good at building boxes or you might just as well have spent your money on a pre-fab and spent the left over money on something else.

PLUS, since we mentioned installers, how many really have any background in speaker design? Many claim to be experts, but in the real world most installers just build the so called custom boxes with no AUDIO PHYSICS in mind. So for a custom box, its important the installer be not only a carpenter but also an expert at loudspeaker box design... Or a pre-fab box might be the better choice! ;-)

And, in reality, there is no PERFECT box, and to really custom build a box to perform as good as possible in a given vehicle it requires huge stacks of expensive test equipment, lots of woodworking tools and saws, and building, testing then rebuilding and retesting, and rebuilding and retesting again and again and again until no more good is achieved. This is done only by a few crazy competition gurus or a few nutty hobbyists, certainly NOT for the average car audio guy, or even the average installer...

So, I think it would be safe to say most so called perfect boxes are no where near perfect, they can all be improved on. And even if they were perfect, putting them in a car will change them, even the direction the box fires in the car can have an effect!

And it makes me laugh when I hear a fellow say something like " the manufacturer recommends 1.5cu ft for this speaker, it wont work in 1.25cu ft!"

Sure it will!
If that's all the space you have,
build it,
play it,
enjoy it!

There are so many variables involved there is a chance the NON-PERFECT box might even sound better than the so called perfect one! Try it ;-)

Enjoy!

Mapping the Transfer Function

Putting a speaker in a vehicle (or room for that matter) will make the speaker sound different. This is caused by reflections, absorptions and resonance's that exist in that car. This change is called the transfer function.

All cars have a transfer function, typically the most noticeable change to speakers when placed in a car is MORE BASS. More bass is inherent because the car is like a box, an enclosed space that promotes reinforcing reflections of the bass sounds (because the bass waves are long enough to be reflected and still be close enough to in phase and reinforce)....

But the transfer function is more than just a change in bass, it also can cause major changes in the midrange speakers because of the major glass surfaces for the sound to bounce off of! Or the high frequency sounds from the tweeters can be absorbed into the headliner or car upholstery (intentionally sound absorbent by the car manufacturer to absorb road noise)...

So, we cant easily change the transfer function, but we can map it, and then build our system to take advantage of our cars transfer function.

To map the transfer function you will need a Speaker box, a CD with test tones or an audio test generator or a pink noise generator and a decibel meter. There are several CDs available with test tones, I prefer the tone generator but they are fairly expensive and hard to find an install shop with one, pink noise is OK but pink noise generators are probably just as hard to find as audio generators. And for a decibel meter Radio shack sells one for about $30 that will work. Oh, and a piece of graph paper to write down your results.

First, lets map the speaker box. Take your speaker box outdoors in the back yard and aim it away from the house to minimize reflections, hang the SPL meter or microphone for it a few meters in front of the speaker box. Fire up your test tones and set the volume level where the SPL meter gets a reading on most of your test tones (if the low ones don't register don't worry), but not too loud, we don't want to damage the test speaker! Now without touching the volume control, run your test tones and write down on your graph paper the SPL at each tone. You can even make a graph on the graph paper if you want to.

Your results is the frequency response of your test speaker!

Lets put this box in the car and do the test again and see what changes!

Set the test speaker in a nice location, preferably close to where the real speakers will go later. Hang the microphone in the center of the car near where your ears would be if you were driving, and run through the test tones again, reading the SPL meter and writing down the results on the graph paper.

When you done, subtract the back yard numbers from the in car numbers for each frequency and write down your results. For instance, if you had 90dB at 120Hz in the back yard and 95dB in the car then (95-90=5) write down 120Hz=+5dB, and do this for every frequency you mapped. Some frequencies may have negative numbers, this is OK... When your done, you should have a series of frequencies=numbers something like this: 20=+4, 40=+6, 80=+12, 120=+3, 200=0, 400=-3, 600=-4, and so on...

This is your transfer function, you can now look at any frequency and tell what
your car is going to do to ANY SPEAKER you install.

Simple....

Understanding The Basic Car Audio Capacitors

The audio system in our cars is an assortment of different parts. Each and every part in the system performs a specific function. It is with the co-ordination of all the parts, that you can hear the system play those fantastic tracks as you drive along. In the entire system, car audio capacitors have a significance of their own.

What are car audio capacitors?

Car audio capacitors are basically power storages in the car. These capacitors accumulate that power which is essential for the amplifier to produce great sounds. You can hear the booming bass sounds and songs with that much needed punch only because of audio capacitors. Car audio capacitors are also known as stiffening capacitors.

More on car audio capacitors

• Audio capacitors accumulate power whenever it is not required. This power is released when the demand for power exceeds the supply capacity of the power system of the car.

• Audio capacitors are necessary to supplement the regular power supply of the car in order to ensure the smooth functioning of the amplifier. Car audio capacitors usually range from 0.5 farads to 3 farads.

• You have to install a car audio capacitor that complements your amplifier. It is also necessary to place the capacitor as near as possible to the amplifier. For 500 RMS of power output, it is necessary to have an audio capacitor of 0.5 farads.

• There are also digital audio power capacitors. These can also be installed in cars. A digital audio capacitor (usually from 1.5 farads) consists of a turn on and turn off circuitry along with a 24-volt DC.

If you car lights dim when your car audio system produces a deep bass note, then your amp will be greatly helped with a car audio capacitor.

How do I know I need A Capacitor?

Before installation, it's often difficult to predict whether or not a capacitor will be beneficial to you. It's generally best to install the audio equipment prior to making the determination, so that you can address which symptoms need to be remedied and assess the severity of the symptoms. This will not only help you decide whether or not you need a capacitor, but also how much capacitance would be beneficial.

The most common symptom in need of added capacitance is headlight dimming (and sometimes dimming of the interior/dash lights). It's caused by a drop in system voltage associated with excessive current draw. While there may indeed be several loads drawing substantial amounts of current from the electrical system (eg. heat, AC, and so forth), it's usually the transient draws that best manifest themselves in noticeable dimming. This is partly because our visual systems are most sensitive to detecting rapidly changing intensity levels rather than steady absolute differences.

Once you've assessed whether or not the dimming is noticeable (and sufficiently annoying), you must decide whether a capacitor is warranted or if you'd be better served by upgrading the alternator.After initially having your alternator and battery checked out (some places will do this for free), the choice should be based on the severity of the dimming.

A commonly-used estimate for determining the appropriate size capacitor is 1F/kW (one farad per kilowatt). For example, a system running at300W would need a 0.3F (or 300,000uF) capacitor. However, there are several variables at play here, including the capabilities of the vehicle's electrical system (which generally varies from idle to higher RPMs), the efficiency of the amplifiers, and the listening habits of the user (ie. the tone controls and the type of music).

These factors should all be considered when making the determination. Moreover, the voltage drop can be so severe that added capacitance is nothing more than a band-aid. That is, even several Farads of capacitance would not be able to sustain the voltage for as long as the drop persists. This Is when an alternator upgrade may be in order.

How to wire a capacitor?

You can refer to a recent post on wiring Here

Planning Your Audio System

This part of the game can be fun or disappointing depending on what you can do. First I'm going to give you an example system that I believe includes everything you need to have a pretty good system. After that I will show you how to make compromises and leave out parts that may not be as important to you to keep your system within your budget. If you want to go beyond my basic system you probably already know more than what this site can tell you. Also, you do not have to get everything at once. I put my system together over a few years. With a little planning you can upgrade your system in steps and that way its like getting a new system every time you change something instead of getting everything at once!

Basic System: This is my opinion only but I think that a good system should start off with a good head unit that either has a CD player and/or is connected to a CD changer. A good system sounds best when playing CDs, tapes just do not cut it. Next I think component sets are made with fewer compromises than coaxial speakers so I suggest getting a good mid-range/tweeter set for the front. Head units generally do not put out enough clean power so you will want an amp to drive the component set. In the rear where you only need some "fill" for ambiance you can get away with cheaper coaxials and set their level lower than the fronts to keep the sound stage in front. A modest (50x4) 4 channel amp is a good choice here for powering the component set up front and the rear speakers. You could use a good 2 channel amp and run the front and back in parallel on the amp but it would harder to adjust the level between them. Mid-ranges sound best when they do not play bass so you will want a 2 way electronic crossover and use the high pass output to drive your 4 channel amp. I did not forget the bass! Most people are happy with a single 10" woofer or a pair of 12"s. Use an appropriate enclosure and a big amp (at least 75x2, preferably even more). Throw in installation and wiring accessories (like fuses and distribution blocks). Here's an approximate price break down of what this costs in my area. Your prices may be significantly different.

• head unit: $300-$500
  
• 4 channel amp for highs: $250-$400
  
• 2 channel amp for lows: $300-$700
  
• sub(s) (1-10" to 2-12"): $150-$450
  
• enclosure for sub(s): $0 (free air) - $250 (custom)
  
• component set: $200-$500
  
• coaxials for rear fill: $100-$400
  
• crossover/equalizer: $100-$500
  
• wiring and accessories: $50-$250
  
• installation: $0 (do it yourself) - $100 (basic)

This comes out to $1450-$3950! I realize that this is a lot of money and that most people do not spend nearly this much money on their car stereo. However, the things listed above are what I feel is necessary to have a system with only a few compromises. If you are less concerned about highs, get coaxials in front instead of the component set and power them off of the head unit and use some bass blockers on them. This will save you about $400. Getting a bargain head unit can save you some money as well. If you are really not into bass much you can forgo all the bass related equipment and run your component set full range. This will still give you clean sound but not much bass. However, you will save $550-$2300. I would start with what I have listed above and take out parts you do not care about as much. Only you know what kind of system you can be happy with.

Please do not email me asking for recommendations about specific brands. There is a lot of equipment out there that I have not used so I will not comment on them. I am happy with the components that I have but that is as far as I can go with recommendations. When buying equipment try to spend time listening to it before you buy, especially with speakers. Also try to use equipment that is similar to yours when listening in a store. As for amps, it costs money to build a good amp so if you see some awesome price on an amp you have never heard of, it is probably a piece of junk. Stick with good names with amps.

Finally, if you are on a budget (aren't we all?) it works better to upgrade in steps. The most important thing is to have a car audio system that sounds good to you not someone else. If you are happy with just changing the factory speakers and stopping there then just do that. There is a level when that new amp or speaker is not going to make a difference so it is not necessary to always upgrade. There are people who think my system is terrible but it works well enough for me and anything else I do to it would be a minor gain and not worth my trouble. Do not let a salesperson talk you into something you do not need! Good luck!

How to Dial in Your Car's Audio System

Level setting, done by ear, is more art than science. It can be done using an oscilloscope but since few people have one of those laying around we'll cover doing it by ear. Basically you want to start with the first component in the chain (the head unit) and work your way to the last component (the amplifier).

1. Start by turning all of the input level adjustment knobs (gain controls) on your components fully counter-clockwise (to their minimum setting). Set the tone controls (bass, treble, loudness) on your head unit to no boost (bass and treble level = 0 and loudness is off). If you have more than one RCA pair you will want to set each gain adjustment separately. Make sure your fader and balance controls are set to the channel you want to adjust first. This can be an individual channel if you have individual gain adjustments or a pair of channels if you have one gain for two channels.

2. Next set all of your equalizers settings (if you have an equalizer) to the center (detent) position so they produce no boost or cut. What we want is as pure a signal as possible.

3. Put in some good quality source material, preferably a CD with strong output and a clean recording. Hard rock would be a bad choice here. Try something cleaner, maybe acoustic, that you're familiar with.

4. Turn the deck's volume up slowly until you begin to hear distortion. When you hear it, stop and back off slightly until you no longer hear it. If you don't hear distortion, even when the volume is all of the way up then you have a quality head unit. That's what we're looking for.

5. Now with your head unit at maximum undistorted volume move on to the next component. Adjust it's input gain until you begin to hear distortion. Back off slightly.

6. Continue this process until you have all of the components in the chain at their maximum undistorted level.

7. When you reach the amplifiers you may need to wear earplugs to adjust them to their maximum level. As before, turn up the gain until you hear audible distortion. This should be audible even with earplugs in. But honestly, if you have to wear earplugs to listen the distortion level is probably not a factor :)

That's it. Play some music and verify that everything sounds right. Congratulations! You've just learned to properly adjust the settings on your car audio system.

Car speaker basics: what car speaker ratings mean

This guide will prepare you to choose speakers to match your head unit. It covers the principles of peak and RMS power ratings, as well as channels and ohms

Selecting speakers to fit your car’s stereo can be a daunting process. Not only do you have to find a speaker that is the right size, but it is important to match the power of the speaker to the power of the amplifier or head unit. To further complicate matters, there are many different kinds of ratings for each speaker. Don’t worry; with this guide you should be able to decode the numbers.

The first power rating a speaker manufacturer will probably display is the max, or peak wattage rating. They do this because the peak rating is the absolute maximum amount of power that a speaker can handle for a very short duration of time. This power would only ever be reached at max volume during the peak of a song, and even then it would only last for milliseconds.

Max power can be very misleading; if you actually pushed this much power through the speaker for even a second it would blow. Hence, when you are selecting a speaker, you should try and match the peak power of the speaker to the peak power of the amplifier or head unit you are running. It’s OK if your speaker can handle more peak power than the amp can put out. In fact, this will ensure that you will not blow the speaker.

The other wattage rating of speakers is the RMS wattage. In the interest of simplicity we will say that the RMS is the average power that the speaker can handle over a sustained amount of time. At the loudest volume, your stereo would theoretically be putting out its RMS power for most of the song.

RMS power is the best measurement of power handling capabilities for a speaker. Make sure to match the RMS of your speakers to the RMS of your head unit or amplifier. Again, it’s perfectly fine if your speaker can handle more power than your head unit can produce, but not the other way around.

Now that you have a basic understanding of the lingo used to talk about speaker power ratings, it is important that you also understand how to determine the actual power coming from your head unit or amplifier.

When the manufacturer writes the wattage of an amplifier, they will usually write something like 80w peak x4. This means that 80 watts are pumped, at peak power, into four channels. A channel is a line to a speaker, commonly labeled as left front, right front, left rear, and right rear. The problem is that the 80 peak watts coming out of the head unit get split into 20 peak watts per channel. This means that each speaker only receives 20 peak watts. So when you select a speaker, you must select one that can handle at least 20 peak watts. If you have a two channel amplifier, the power only gets split two ways.

To further complicate the matter, most power ratings will also include a number followed by a horseshoe shaped omega symbol. This represents ohms, which is a measurement of resistance. The rating for your amp or head unit will probably read something like this: 80w peak x4 @ 4Ù (ohm symbol). This means that at a resistance load of 4 ohms, the amp will be produce 80 peak watts (20 per channel). The resistance of 4 ohms will be coming from your speaker. Hence, the best speaker choice will be one that has 4 ohms of resistance, and can handle 20 peak watts per channel.

It is generally not recommended to use a speaker with a different resistance rating than the amp that will be supplying it. However, if you do, keep in mind that if the resistance doubles (as with an 8 ohm speaker rather than 4), the wattage will be cut in half. Conversely, if the resistance is halved (a 2 ohm speaker instead of 4), the wattage will double.

If you keep all of this in mind as you are selecting a speaker, you should be able to make a good choice. Ideally, you will find a speaker that perfectly matches your head unit. If not, remember to always err on the side of too much power handling as far as your speakers are concerned.

Find the best stereo for your car

You can find out how to choose the best stereo for your car by reading this informative article!

The first thing to do is to check with your family members and friends to see what kind of stereo equipment they have in their vehicles. Referrals are sometimes the best way to find a reliable brand. The next step is to start shopping around in electronic stores to see what brands there are, what kinds of stereos are available for purchase, and what options are available. Be sure to check on what kind of a warranty that each stereo carries. Decide at this point what you want in a stereo and what you do not want. Decide what you would like to have, but what you can live without. For example, do you really need twenty radio preset buttons or can you live with only six? Beware of the extras that you may not need. If you are not going to use them, then do not buy a system with them on it. The more the gadgets, the higher the cost of the stereo, of course. Decide on how much money you can possibly spend. Talk to sales clerks and ask their opinions about the different kinds of stereos. Ask what kind they have in their own vehicles. Ask at each store whether-or-not they are authorized dealers of the products that they recommend. If your stereo needs repaired, can you take it back there and have it fixed?

Ask each sales clerk if they can demonstrate each of the models they carry? Obviously you will want to hear the differences in the stereos before you finally choose one and buy it. Find out if they will install the stereo too. Ask them the exact steps that they would take in order to accomplish the task. Find out if they have any pictures of their work. This especially pertains to the installation of the stereo's speakers ans subwoofers. If you purchase a stereo and speakers that are the same size as what you currently have, then the new equipment can simply be put into the same spaces that your current equipment is in. But, if you purchase bigger speakers that will need more space to accomodate them, then these units need to be enclosed first, and then covered with carpet to match your car, truck, or van.

Stereos for your vehicle usually start out with the basic AM/FM radio unit. That is the most basic stereo you can get. Then, there are models that also have cassette players and CD players, etc. Name brand stereos and speakers are probably the better route to take when choosing. You will undoubtedly get a better sound and performance from a name brand that you can trust. Stay away from cheap models that probably sound tinny, muffled, or otherwise unnatural. The cheaper brands tend not to hold up as well as the name brands too.

Finally, the sales people will probably try to talk to you about woofers and tweeters and frequencies, etc. To put it in plain English, the woofer handles the bass frequencies and the tweeter handles the treble frequencies. If you are really interested in this, that is fine. But, if you are not, then that is all you need to know. If you don't understand the lingo of the stereo world, don't let them baffle you with foreign sounding words, technical terms, and other information that you really don't need to know.

CAR ALARM & REMOTE CAR STARTERS

Car alarm is an electronic device installed in a vehicle (car, truck, boat, motorcycle) in an attempt to discourage theft of the vehicle itself, its contents, or both. Alarms work by emitting high-volume sounds (usually a siren, Klaxon, pre-recorded verbal warning, the vehicle's own horn, or a combination thereof) when the conditions necessary for triggering are met, as well as by flashing some of the vehicle's lights, and (optionally) notifying the car's owner via a paging system and interrupting various electrical circuits necessary for the car to start.

Many Poeple get confused between an alarm and immobilizer. An immobilizer is an electronic device fitted to an automobile which prevents the engine from running unless the correct key (or other token) is present. This prevents the car from being "hot wired" after entry has been achieved.

Car Alarm Advantages:

Having an expensive aftermarket system in a car without an alarm is asking for trouble. I've heard too many stories of people learning the hard way and losing a lot of money when they find out that their aftermarket audio system was not covered by their insurance. Car alarms may not be able to stop the thief but they do attract a lot of attention to the thief's activities. Besides having an alarm system, here are a few other pieces of advice to keep your systems in a safe place.

* Don't drive through neighborhoods blasting the bass and calling attention to your system. Not only is this a courtesy to the residents but it also keeps the local hoods from scoping your ride as their next target.

* When parking your vehicle, try to park under lights and in an area where it is not hidden from view. Keeping it in the open reduces your chance of a thief breaking in to it. Thieves hate to be seen.

* Try to keep areas within the vehicle looking as stock or stealth as possible. Large aftermarket grilles are a nice advertisement that you have more than OEM equipment. Try to concentrate style in areas that are hidden from the exterior view, such as in the trunk.

Car Alarm Types:

There are two main types of car alarm activation methods. Passive and active. Passive alarms automatically enter an armed state after the ignition is turned off and the last door is closed. Active alarms require the user to press the transmitter button to arm and disarm the system. If you set your alarm to arm passively you can probably get a discount on your insurance. Check with your insurance provider. You may get a discount either way. Most good alarm systems can be configured as passive or active arming.

An alarm system should be put in at the same time or before a stereo system is put in. By waiting until after the system is in you run the risk of having it stolen before the alarm is installed.When shopping for an alarm, don't be cheap. A good quality unit can be purchased for about a hundred dollars if you shop around. For two hundred dollars you should get an alarm with some extensive features built in. Installation for the car alarm will run about one hundred dollars and up depending on how many extra features that you want hooked up and how fancy you want the installation to look. Keep the appearance on at least the same level as the stereo system, especially if you plan on competing in car sound off competitions.

If you want to install your own car alarm or remote car starters, make sure you read the manual carefully.

Car Alarm Features:

There are probably more features available on a car alarm than any other single category of equipment available for your system. There are new features constantly popping up on the market. Here are some of the most common.

Active Re-arm: After the alarm has been disarmed the system will automatically re-arm after a specified amount of time if a door is not opened. This is to prevent accidental disarming by the remote transmitter.

Air Horns: These are used on the interior or exterior to call more attention and cause pain to the thief if he makes it into the interior of the vehicle.Anti-Code Grabbing: A method employed to change the alarm code with every arm/disarm. The purpose of which is to defeat code grabbing equipment that can capture and resend your code to disarm the alarm at the thief's leisure.

CAR SPEAKERS INFORMATION:

Car audio speakers were used in cars for the purpose of avoiding the stress of driving and to have leisure and avoid being bored while traveling. It’s of course a part of the stress management while driving. But remember don’t make desperate others by increasing the volume of your speaker.

Installing car speakers is most pocket-friendly. You can find car speakers in a wide range of prices, depending on the size, power, number of speakers, brand name, and a few other factors. And not only are the speakers available in the local market relatively inexpensive, they are typically not difficult to install at all. You can either install them yourself, or you can hire the services of an expert. Oftentimes, the company that sold you the speakers will be able to install them for you as well. Otherwise, if you feel like doing it yourself, make sure you follow all instructions.

You can install the speakers by means of a few tools that you probably have around your house. Each car presents its own specific type of installation issues, varying on factory speaker locations, mounting depth and height, and the vehicle's factory wiring. Many installations are straightforward. A screwdriver might be all that you require to complete the job. Other installations can be more involved, particularly if you're installing component speakers. Every car is different, so you may have to ensure its installation as prescribed in its brochure and it may differ from one to other. Lets know something about its installation.

CAR GPS NAVIGATION SYSTEMS PRODUCTS:

Do you find that you have a lot of speeding tickets? Maybe you even have trouble remembering where to reduce your speed? There are of course many ways to solve your problems. Even if you don’t have speeding problems you probably find you have navigation problems when you are in a new area of the city. Undetected is just one company that offers satellite navigation and speed camera detectors. If you are interested in GPS satellite navigation you should check out the products available and compare pricing.

Undetected offers you a range of products including a dual satellite navigation system and speed camera. These units will help you navigate the city as well as reduce you speeding tickets, traffic violation fines, and traffic accidents. The Indic8tor is one of the latest GPS satellite navigation systems.

This GPS will warn you when you enter a new speed zone, aid you in safe driving, and give you voice alerts. The voice will allow you to know when you are exceeding the limits as well as offer guidance. Another GPS navigation system is the Snooper S3 GPS. This GPS stores geographical coordinates and even tells you of "black spots" on the road. A black spot is usually considered an area where a lot of accidents happen. The Snooper S3 GPS will compare your position with a GPS antenna to give you the most up to date information on speeds and accident spots.

There are many other GPS navigation systems available and tips on how to use them. You will want to understand the laws of your area as well as how these systems can help you reduce accidents or violations. Undetected will offer you information about the law as well as facts about the products they sell to help you find the best product for your vehicle.

CAR STEREO INFORMATION:

When purchasing a car stereo system, finding quality car stereo amplifiers is critical. Unless you know in advance what type of amplifier you are going to purchase, you will need to research the various styles and prices of car stereo amplifiers. The amplifier you buy should be the best you can find in your price range. Not all car stereo amplifiers are created equally. Car stereo specialty stores and the numerous web sites devoted to creating the ultimate car stereo system can be of great value to you when researching amplifiers. As with any other car stereo component, amplifiers vary in quality and price. The highest priced amplifier you find will not automatically be the best for your particular system. Finding quality car stereo amplifiers will take knowledge on your part. If the staff at your local car stereo store is not willing to explain the differences to you, then go on to the next store. You do not have to spend large amounts of money on a quality car stereo amplifier.

Different amplifiers work better with some car stereo systems than with others. You should know where your amplifier will be located, how it will be installed, and what you expect as far as sound quality before you purchase your new amplifier. For those who compete in car audio competitions, a higher priced amplifier may be able to give them just the type of sound they desire. For the average car stereo, a less expensive amplifier will work just as well. If you have invested a lot of money in your car stereo system you may want to go ahead and invest in a top quality car stereo amplifier. If you have purchased full range after market car speakers then a lower priced amplifier will suit your needs. Finding quality car stereo amplifiers is no different than shopping for any other car stereo component. Research your choices thoroughly and have a clear idea of what you intend to accomplish with your amplifier. There is no need to purchase the most expensive amplifier if you are simply putting a superior stereo system in your personal vehicle. If car audio competition is your goal you will want to find a more expensive, top quality car stereo amplifier. Make wise decisions by learning the facts before you purchase a car stereo amplifier.

CAR SUBWOOFERS INFORMATION:

Having a subwoofer as part of any audio system is a key element and a crucial factor in having excellent quality sound reproduction. Whether the setup be at home or in your car, a subwoofer adds depth to any sound output by emphasizing key low frequency sounds that most typical speakers will never be physically capable of achieving.

A typical car audio system is composed of four medium size speakers (6-3/4” diameter or smaller), usually mounted on each of the front side door panels and two usually mounted on the deck above the trunk behind the rear passenger seats. These speakers could be called coaxial speakers because they usually have an additional tweeter (1-1/2” diameter or smaller) mounted right on top of the speaker cone. The combination of the two will allow the audio system to pick up most of the middle to high frequency sounds and reproduce them so that the sound is audible to the human hearing. Typically, this configuration covers frequencies from 2000-20,000 Hz. However, the human sense of hearing could pick up frequencies as low as 20 Hz!

A subwoofer emphasizes frequencies as low as 10 Hz (not usually audible in human hearing) all the way up to about 1000 Hz or more depending on the subwoofer. The result of adding a subwoofer to a standard audio system is a much fuller sound, primarily due to the fact that human hearing could hear much more and in all honesty, your ears want to hear more. You know something doesn’t sound right or doesn’t sound good, and it makes you feel relieved when you do hear something that has full depth of sound.

If you let each speaker do their job with emphasizing their specific frequencies they are designed to reproduce, then adding a subwoofer is like hiring a new employee that is specialized in a certain job. Even certain subwoofers are specialized for different tasks.

Subwoofers that are classified or measured at 8” to 10” will never produce as much as bass as the larger 12” or 15” subwoofers. 8” Subwoofers and most 10” subs are primarily designed to add depth to a sound system; they typically do not feature any show-off performance such as that “boomy” sound. These smaller subs are recommended for music lovers without the urge to rattle every car at the stop light. Because these are smaller subs, they require a lot less box volume than larger subs. You could probably use 8” or 10” subs in compact to medium size sedans, hatchbacks, and SUVs.

12” Subwoofers are typically used by consumers who are a bit more into the loudness and “boomy” factor that subwoofers could produce. Expect to rattle more cars with 12” subs, as it typically produce deeper bass and higher power handling. You should probably prepare a large area for the setup of 12” subs. Subwoofers this size are typically found in larger vehicles, such as full-size SUV, pickup trucks, or luxury-size sedans.

Large-size subwoofers measuring at 15”, 18” or other custom-sized subs are primarily used in competition settings. Most subs this size are emphasized for performance and loudness—not so much on sound quality. You’ll rattle a lot of cars, make a lot of stationary objects move, and maybe make your mom nauseous from all the frequency noise. You will usually need to customize your vehicle to accommodate these behemoths—so wherever it fits the enclosure is just fine. But remember, the bigger the subs, the bigger box it needs.

Not All Car Subwoofers Are The Same:
Basically subwoofers are of either a passive or powered type. A passive subwoofer setup will get its' power from the car audio system. A powered type of setup will get its power delivered independently of the car audio system being used. Car subwoofers are commonly put into box enclosures that they are mounted on and then placed into a suitable place in the car which is usually the boot area. Car subs vary significantly in size with usual ranges being from 8 inches to 60 inches. These days you can pick them up relatively cheap online from places such as ebay.

Car Sub woofer Setup Arrangement:
So far we know most subs are mounted in boxes but they can also come in a tube mounted format. Typically a sub will have an amplifier connected to deliver the power required. The power delivery requirements are significant so for that reason an amp is pretty much a necessity. They also typically take up a lot of space so be prepared to give up that room in order to accommodate your car subwoofer.

Buying Your Own Bandpass Car Subwoofer:
Go for the best one that your budget can withstand. If you can't quite afford the good ones in retail outlets then have a look at online auction sites such as ebay. There are some real bargains on there. Remember, buying a used car subwoofer in great condition and decent quality could be better than buying a new one that isn't very good. Even though car subwoofers are considered a luxury item, many car audiophiles would not go without this piece of kit in their setup.

CAR AMPLIFIERS INFORMATION:

An amplifier takes a signal from a source and makes it larger. This makes the sound louder. The hard part is amplifying the signal without adding any distortion. Amplifiers must have a power supply strong enough to keep them going and must store enough current to deliver all of the transients in the music.

How they work
A cassette radio or CD player produces a maximum of about nine real watts into four speakers given the power it gets from the car's electrical system. So what if you want more than nine real watts to power each of the speakers? You obviously need an amplifier. Amplifiers give more power allowing you to play your music more loudly.
Amplifiers also improve the sound quality of music at all volume levels.

Features of Car Amplifiers
Here are some important facts you should be aware of if you want to choose the right amplifier...

• Bridging amplifiers are very flexible because they can be used in different system configurations. One amplifier can be used to power one, two, three or four speakers.

• Speaker-level inputs are the only way your car amps can get signals if your radio doesn't have RCA-type output jacks.

• Preamp outputs are very useful when creating a multi-amplifier system because they allow an un-amplified signal to pass out of one amplifier to another.

• Remote bass control is available in some amplifiers that have a port to add an optional control knob. This varies the amount of power going to the subwoofer driven by the amplifier.

• High-pass filters, low-pass filters and crossovers give you the flexibility to remove the frequencies you don't want to send to the speakers powered by the amplifier.

• Bass boost is available in some car amplifiers. This lets you boost the bass significantly up to 18dB through a circuit.

An amplifier can have one channel of output or as many as eight channels. The most common amplifiers are two and four channel models but mono amplifiers are also becoming popular.

Main classes of amplifiers:
Class A amplifiers gives the least distortion, but are terribly inefficient. They are rarely used in commercial amplifiers because they produce too much heat and give too little output power for the effort. In class A the output transistor(s) are always conducting, even at idle with no signal. The power draw of a class A amplifier is roughly constant and they are most efficient at full-output. If the load ends up drawing too much current the amplifier can wind up leaving class A (one transistor switches off in a push-pull, for example) during a cycle.

Class A/B is what most commercial amplifiers are. They are much more efficient, but do produce more distortion. A class A/B car amplifier is formed when a class B style output stage is biased so that around the crossover point both transistors are conducting. This yields more distortion than either a proper class A or class B amplifier, however the bias point is much less critical.

Class B amplifiers have two transistors, one per supply rail. In properly-biased class B, only one conducts at a given time, but there is always one conducting. Much of the bad name class B has is due to amplifiers actually being under biased into class C where there's a portion of the cycle around the crossover point where neither is conducting.
Furthermore, Class B proper biasing may be made very difficult to achieve due to thermal stability issues (especially proper thermal coupling and tracking between the biasing circuit and the output power devices). Class C amplifiers are useless for audio. They are used in RF applications where the harmonics can be filtered out.
Nonetheless, the so called "Class G" is just the plain combining of a normal Class AB car amplifier output stage with a Class C "booster" enabled to operate only if high power peak are required by the load. If properly designed they performances are equivalent to that obtained by normal class AB amplifiers.

Class D amplifiers are a rather new phenomenon in the hifi world. They are extremely efficient (80%) and can give a very good result. They use pulse width modulation to amplify the signal; this lets them use the output transistors in switch mode where they're most efficient and dissipate the least power. Originally only for subwoofers, newer designs have since surfaced making this technology capable of sounding very good as a full-range amplifier.

A class D amplifier is one in which the output transistors are operated as switches. When a transistor is off, the current through it is zero. When it is on, the voltage across it is small, ideally zero. In each case, the power dissipation is very low. This increases the efficiency, thus requiring less power from the power supply and smaller heat sinks for the amplifier. These are important advantages in portable battery-powered equipment. The “D” in class-D is sometimes said to stand for “digital.” This is not correct because the operation of the class-D amplifier is based on analog principles. There is no digital coding of the signal. Before the advent of the class-D amplifier, the standard classes were class-A, class-AB, class-B, and class-C. The “D” is simply the next letter in the alphabet after “C.” Indeed, the earliest work on class-D amplifiers involved vacuum tubes and can be traced to the early 1950s.

The high switching frequency used in class-D amplifiers is a potential source of rf interference with other electronic equipment. The amplifiers must be properly shielded and grounded to prevent radiation of the switching harmonics. In addition, low-pass filters must be used on all input and output leads, including the power supply leads.