How Do Speakers Work?

Speakers are air pistons that move back (on the negative cycle of the signal) and forth (on the positive cycle), creating different degrees of air pressure at different frequencies. The amplifier (either separate or built-in your radio), produces electrical impulses that alternate from positive and negative voltages (AC). This current reaches the voice coil inside the speaker, creating an electro-magnet that will either be repelled, or attracted by the fixed magnet at the bottom of the speaker. The voice coil is attached to the cone, moving it back and forth, creating sound. The surround (rubbery circle that joins top of the cone and metal basket) and the spider (usually yellow corrugated circle joining bottom of cone to magnet) make the cone return to its original position.

Speaker Sensitivity, measured in dB, is how loud a speaker plays (usually 1 Watt, 1 meter). A higher Sensitivity rating means that the speaker will play louder using the same power as a speaker with a lower rating.

The back and front parts of the speaker should be isolated from each other. When the front of the cone is pushing air, the bottom is pulling air, creating a canceling effect. Ideally every speaker should be in an enclosure. If you are mounting a speaker in a big hole, make sure you build a panel to isolate the front and back of the speaker (baffle).

Imaging, Staging and Directivity

Imaging - is being able to pick certain sounds from different places. The singer would normally be located towards the middle of the car, guitars, trumpets, and other instruments towards the sides of the car. If you scatter speakers all around the car your imaging would be very poor, since you would be producing the same sound at different places. If you have a system with good imaging, the sound should seem to come from different instruments and voices, not speakers.

Staging - is the ability of a system to “fool you” into thinking that everything (including bass) is in front of you. The sound should be similar to a stage in a concert, where the singer would be in the front center, and the rest of the instruments and background vocalists would be located to the left and right (but always on the front).

Good staging and imaging are not so easy to implement. It takes a lot experimenting with speaker location and direction.

Directivity - of sound is related to frequency. At higher frequencies it is easier to pinpoint where the sound is coming from than lower frequencies. This can be used to our advantage in car stereo. Tweeters are the most important part of getting good staging. They should be aimed towards the middle of the car. A way to “bring” the bass to the front of the car is to fool our ears by overlapping frequencies played by midbases and subs, so that your midbases actually “pull” the bass to the front, since lower bass in not too directional. You should crossover your midbases as low as you can (without getting distortion). Then cut your subs at a bit higher frequency (preferably 60 HZ or less). This will mix the bass coming from the front and rear, making the bass seem to come from the front. Adding a center channel also improves staging, if it is set up correctly.

Types of Speakers

Coaxials - Coaxial speakers (or three-ways) are two (or more) speakers built-in the same frame. They are cheaper than separate woofer and tweeters and also easier to install. There is no need to worry about crossovers, since they are already built-in (you might still need to add a crossover to block bass if you are using high-power amplifiers). A disadvantage of coaxials is the lack of flexibility. For example, if the coaxial is all the way in the kick panel, or door panel aiming at your feet, you will not have good staging or imaging. Some manufacturers try to compensate for this by making adjustable tweeters. You should usually consider coaxial speakers for the back of the car, and separates for the front, unless you only have one speaker hole and don’t plan to cut any more holes in the car.

Separates - Separates consist of a tweeter and woofer, and [most of the time] come with an external crossover. The woofer is usually mounted in the factory hole in the door or kick panel. The tweeters can be mounted in different places. The most common place to install tweeters is towards the top front corner of the door panel, aiming (if possible) between both front seat head rests. Another popular location for tweeters is in the dash, either surface mounted, or in factory dash holes. Yet another location where tweeters are commonly mounted is in the blank plastic piece on the top front side of the doors (where the mirror is on the outside). You would have to experiment with angle and location to achieve the best possible imaging and staging.

Horns - Horns are very good at directing sound and have high efficiencies. Horns are usually mounted under the dash. By doing this, difference in distance from left and right speakers are greatly reduced over conventional mounting locations. Since horns play mids and highs, tweeters are not needed. Horns cost more than conventional speakers and require customization. In many installations a good equalizer is required to compensate for their high sensitivity.
Horns are not for everyone though. Many audiophiles complain of unnatural sound. It is very hard to properly setup a set of horns.

Midbases - Midbases are usually 5, 6 or 8 inch speakers that are designed to go lower in frequency and are part of a three way system with a mid and tweeter. The problem is that 3-way arrangements require more complicated crossovers. Midbases are most commonly mounted in the doors.

Subwoofers - Subwoofers add lower frequencies to the system. They have to be enclosed in a box, with the exception of free air subwoofers, which use the trunk as an enclosure. There are many different types of boxes and implementations discussed in the “subwoofers” section.

Mounting Locations

Front Speakers - The best place to mount speakers in the front, in custom kick panels. By doing this, the path between the speakers and ears is minimized giving the best possible sound without having to add time delay circuitry. If this is not possible, try to point the speakers towards the center of the car, and try to minimize the distance between the right and left speakers to your ears. Custom kick panels are usually built from fiberglass or molded plastic, and are available from some manufacturers such as Ai Research.

Rear Speakers - Rear speakers should give a sense of space to the music, but not overpower the front speakers. You should be able to barely hear the rear speakers. If you are using rear speakers to add more bass/midbass to the system, at least use a crossover to cut off higher frequencies. A lot of hi-end systems don’t even have any rear speakers. Tweeters are not necessary for the rear, a set of coaxials will work good for rear fill.

Center Channels - Center channels consist of a midrange speaker (3 or 4 inch) mounted in the middle of the dash (usually) on the top. Center channels play a mono (Left + Right) signal between 350 - 500 and 3500 Hertz (voice range). The purpose of the center channel is to raise the sound stage, by creating the sensation of the singers “being” in the front of the car, and not in the door panels. Center channels are hard to implement: First, a bandpass crossover is needed. Left and right channels have to be summed up. There are various commercially available center-channel processors (many with built-in amplification). The volume level of the center channel should be lower than the other speakers, since it is only supposed to make subtle changes to the total sound image.

Sizes and Shapes

There are many speaker sizes ranging from 1-inch tweeters to 18-inch (or bigger) subwoofers. A smaller speaker will reproduce higher frequencies better than a bigger one. The wavelength of a 20,000 Hz signal is very small, while the length of a lower (bass) note moving in the air could be as big as 40 feet. That explains why a 4-inch speaker can’t really put out bass (the lower the frequency, the more air mass that has to be moved by the speaker). Tweeters are designed to play frequencies from 3500, 4500 or even 6000 Hz, all the way up to 20,000 Hertz. Midranges (3, 4 or 5 inchers) play music from around 300, 500 Hz, to where the tweeters start in the upper level. Midbases (5, 6, 8 inches) play from around 50 Hz to 500 (and even 1000) Hz. Subs handle frequencies below 120-60 Hertz.

Do round speakers sound better than oval-shaped speakers (i.e. 6×9’s)? The answer is yes for most practical purposes. A round cone is more rigid than an oval-shaped one, so at higher levels, an oval-shaped speaker will distort more. The reason why there are oval-shaped speakers is because of rear deck space considerations by manufacturers. An advantage of a 6×9 speaker over a 6-inch speaker is that it has a bigger area, so it will move higher air volume, producing more bass.

Power Considerations

Most people think that if they use a 50 watt per channel amplifier on their factory speakers, the speakers will be damaged. This may be true if the speakers do not have crossovers blocking off frequencies speakers were not designed to play. What destroys speakers is distortion. If you turn the volume all the way up on the radio, there will be distortion. If you start hearing distortion, turn the volume down. A high power amplifier allows the volume in the system to be higher, while the volume control on the radio is down in the range where no distortion is present. It is better to have more power than what you need to get cleaner sound.

So how much power do you really need? As much as you can afford. At a minimum, 30 to 50 Watts (each) would be OK for your front and rear speakers, while a little bit more (100-150 Watts) should be applied to each sub. If you are powering up your tweeters independently, they require less power (20 - 40 Watts). Example: A four-channel set-up with separates in the front and coaxials in the rear with two subs will need about 40 Watts on each channel (Total=160W), and 100W going into each sub (Total=200W). Notice that total power going to subs is more than total power going to the rest of the speakers. This is because our ears are less sensitive to bass.

Car Audio Amplifiers

The purpose of a car audio amplifier is to take a low level signal from the source unit and change it into a high level signal for driving the loudspeakers. Amplifiers range in power from about twenty watts per channel to over one thousand watts per channel. The price range can be anywhere from fifty dollars to several thousand dollars depending on features, power output and quality. An amplifier may have as little as one channel of output to as many as eight channels at the time of this writing. The most common amplifiers are two and four channel models although mono subwoofer amplifiers are gaining in popularity.

Amplifier Power Ratings

Extra features may also be built into a power amplifier. These features include built-in active crossovers, equalizers, signal processing and speaker level inputs. When shopping for an amplifier consider that all power ratings are not created equal. Some of the low-quality brands will exaggerate or even outright lie about the power output of their amplifiers. This is a good reason to stick with the well known manufacturers. The only true measure of an amplifier’s power is its continuous power rating or R.M.S. rating. R.M.S. is an acronym for root mean square and refers to the amplifiers average power output.

Car Amplifier Quality

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. For example, Blaupunkt makes a line of amplifiers that have a plastic shell. 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. 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: 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 rare in car audio. 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.

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.

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.

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 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.

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 can be three times less than the actual power output.

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 twenty 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 (usually RCA 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).

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.

Get the Perfect Amount for Your Photo Needs

Probably the most significant feature when choosing a digital camera is the number of megapixels, which determines the quality of your photos. Choose too few for your needs, and your images will suffer. Choose too many, and you might be spending more cash than necessary.

For most people, however, deciding on the elusive perfect number can be tough. Below is a guide to help you choose, including what size prints you can expect to get and basic prices. (The prices, however, can fluctuate wildly based on extra features, and the cost per megapixel is constantly getting lower and lower):

2 megapixels or less

• This is typically found on smaller, inexpensive cameras or cameras in combination with other devices (such as cellphones or PDAs).
• It will be hard to make a high-quality print of any size, but these are just fine for e-mailing photos or posting photos for a personal web site.
• I wouldn’t recommend it for family portraits or if you really need a nice-looking print.
• Expect to pay $100 to $150 for the camera alone, more for a combo unit.

3 megapixels

• This is actually a good compromise between picture quality and low price for most casual photographers.
• You can print lovely 4×6 images, decent 5×7s and, depending on the camera, might even knock out a good 6×9 or 8×10.
• You will pay around $150 to $250.

4 megapixels

• You’re getting nicer. These images make practically photo-lab quality 4×6s, and great 5×7s and 6×9s.
• You can print a nice 8×10.
• You’ll typically pay about $250 to $350.

5 megapixels

• Hello, enlargements! This will produce beautiful 8×10s, and even a nice 11×14.
• Now you are getting closer to professional photographer levels, and the quality shows it.
• And you’ll pay the price, around $350 to $450.

6 megapixels and up

• Wonderful image quality, but high price tags. You can print large photos, even 11×14 or perhaps more, with satisfying results.
• There are some high-megapixel cameras coming out with lower price tags than most, but they usually have very few features.
• Unless megapixels are the only thing you care about (it shouldn’t be), don’t get a camera that sounds outrageously inexpensive for its megapixel range.
• In this category, expect to pay $450 and up, up, up.

Yes, I know it would be really cool to get that hot new 6 megapixel camera. If you have unlimited funds, great. If you’re like the rest of us working stiffs, you don’t want to waste money on extras you don’t need. And I can tell you right now, if you’re just e-mailing pictures to your buddies, you don’t need it.

A couple things to keep in mind. People get nuts about megapixels, but more isn’t always better. Higher megapixels means larger image sizes, which in turn means more expensive memory cards and more space devoured on your computer’s hard drive.

Do you want to listen to music while you’re on the go? Its time you think about purchasing a MP3 player/portable mp3 player to get the music off your computer to listen on the fly. If you have been thinking about getting an MP3 player/portable mp3 player then take a moment to compare the two main types of players. The two players include hard-drive and flash memory players. Each one has its own advantages and disadvantages, so we will take the time to cover them to give you a better insight for you buying decision.

The hard-drive MP3 player are just like a computer with the hard drive located inside. You can store a lot more digital files on the drive for the serious listeners. Since you can store more media files on the drive, these players tend to be more expensive and bulky. These are not the best for use during exercising because of the size. Hard-drive MP3 players also have moving parts, so skipping can occur during high-impact situations.

The flash memory MP3 players are small and more compact than the hard-drive players. These portable MP3 players have built-in flash memory that store the music files. There are no moving parts to worry about so they tend to be very good for exercising and high activity situations. These players have limited memory space so they will not hold as many songs as the hard-drive MP3 players.

So before you just go out and buy an iPod, look at what you want to have it for. Do you want to listen to music while exercising or doing strenuous activity? Do you want to put your whole music collection to have it with you for any occasion. These are just a few questions you need to ask yourself when thinking about a mp3 player or portable mp3 player. One of the large crazes now is being able to hook your portable mp3 player up a car stereo so you can listen to music while driving without switching CDs. If you want to do the same, then look for a car cd player that is capable of reading a mp3, so you can hook up your mp3 player and listen to all your music without touching another cd. Good luck with your mp3 player shopping!

You’ve probably heard about progressive scan DVD players, but you may not know what exactly they are or why they seem to be the hot item that people want these days. To understand why this is the case, first you need to learn about the different technology that progressive scan DVD players provide. And then you’ll need to realize that at the moment, only those who have invested in HDTV or other high performance display screens or projectors will be able to take advantage of the difference.

To start with, let’s review the way that traditional motion pictures are created. In fact, the term ‘motion picture’ is rather misleading because no pictures actually move. Instead, still pictures, also called frames, are played in rapid succession so that the resulting display is changing so quickly and in such small amounts at a time that we perceive it as moving. You may have recreated this illusion in school or on your own by drawing stick figures or other pictures on a stack of paper, then flipped through the paper quickly. The figures looked like they were moving rather jerkily. But if you took the time to draw enough frames and move them quickly enough, you would see much smoother motion, like in cartoons.

Television is recorded in the same type of frames. Then it’s broken down to be transmitted in a signal. When the signal is received by your television, it is reassembled in sections, or stripes. These stripes are reassembled in two different sets, from top to bottom and left to right across your television screen. To explain this concept more clearly, imagine window blinds that are partly open. The actual blind pieces are one set of stripes and the space between the stripes represents the second half of stripes. In a TV transmission, the stripes of set one are laid in before the second set is laid in. This is called an interlaced display. Although it sounds like it would take some time, all of this happens in the fraction of a second - 60 of the fields or stripes are displayed per second.

DVD players and DVDs have used this same technology because of the fact that TVs displayed pictures this way. But with the advent of digital and high definition television projectors, display technology has changed, leading the way for DVD technology to change as well. These high performance TVs and projector screens receive and display signals in full progressive frames instead of stripes. And 60 full frames are displayed per second. Meaning even more detail can be included in the same amount of time, resulting in pictures with less flicker or picture distortions. Progressive scan DVD players work by sending DVD signals in the same progressive format.

However, progressive scan DVD players only make a difference if they have both the source material that can be scanned into progressive signals and the display screen that can receive progressive signals. Older DVDs were most likely not recorded with progressive signals. Newer ones will have the capability, though. But as mentioned before, you have to have a television that can receive progressive signals. HDTV televisions can, and so can CRT or LCD monitors.

If you have the right kind of television, a progressive scan DVD player, and a DVD that was produced in the last 5 years or so, you can test to see if you can tell an improvement. Just switch the DVD playing setup from progressive to normal as you watch the film. Look at the outline of things, and the details of the background elements. You may just experience home video with a clarity and sharpness like never before.

In-dash monitors are one of the most exciting new mobile electronics products to come along in recent years. The simple fact that engineers can fit a 7″ widescreen monitor into a standard (single-DIN) size car stereo is a marvel in and of itself. But watching the screen motor out horizontally from the stereo chassis, extend, and then flip-up into a 90° position for viewing is a thrilling spectacle. As Advisor reporter Matt Freeman notes, “There’s something inherently cool about watching a monitor automatically slide out when you start your car.”

As mobile video has grown in popularity, in-dash monitors have become an essential component for many in-car video systems. Most new in-dash monitors are now packaged with a built-in DVD/receiver, giving you an all-in-one mobile video package for the front of your car. Watching a DVD on your in-dash monitor within the cocooned space of your parked* car can be an impressive experience, especially if you’ve got a subwoofer and good quality speakers driven with enough power to reproduce sound effects and dialogue effectively. (*In-dash monitors do not allow you to view a movie when the vehicle is in motion.)

But you can use an in-dash monitor to do a lot more than just watch movies in your parked car. An in-dash monitor can add a whole new level of safety, convenience, and (yes) flash, to your car stereo system. You can’t watch a movie on your in-dash monitor as you cruise down the road, but you can use it to do some pretty cool stuff:

• An in-dash monitor is an essential component of an in-car navigation system, an increasingly important feature for more and more drivers these days.
• An in-dash monitor provides a vivid and often interactive display of all sorts of system information in a large and legible format.
• An in-dash monitor will display MP3 ID3 tags and WMA folder and file information, for easy navigation through hundreds of songs.
• An in-dash monitor will display channel, artist, and song information for satellite radio.
• Drivers of large vehicles like SUVs and RVs, and those who often tow a trailer, can use an in-dash monitor to display back-up camera images.

If you are thinking about putting a beefed-up system in your vehicle and you are not so sure how to get the power that you want, then you need to think about an amplifier. Amplifiers can be used for any system that you want to put in your car or home. Amplifiers allow you to create a mobile sound system that can bump like no other. You can still have a conversation while traveling if you have an amp, but your sound quality will be much improved. Here are some of the added benefits of an amplifier for your system.

It’s time to replace those factory speakers: If you want to beef-up your audio system, you should think about replacing your car speakers. The only problem is that the factory receiver will not be able to do your new top of the line speakers justice. You will need to get an amplifier to allow for max performance from your new car speakers.

Putting some bass in your life? If you want to add some bass in your new system, then an amplifier is a must have. Your receiver is not going to have enough power to maximize the subwoofer performance. Subwoofers require a lot more power than what you will have stock, so add an amplifier and get your bump on!

Increase that sound quality! When you think about replacing your car speakers and system, you might want to increase the quality of sound that is produced. Your receiver can do the job, but if you want a clear sounding system, then adding an amplifier will do your new system justice. The amplifier will give more power to the system allowing your speakers to get all the necessary power to produce a wonderful, crystal-clear sound.

There are many types of amplifiers out there and you will have to find the right one for you and your new car audio system. There are a few tips that can help you choose what you want to use to provide the maximum performance. If you want to just power subwoofers, than you can use a 2 or 4 channel amplifier. If you have one subwoofer, then a 2-channel amplifier will do the trick. If you have 2, then a 4-channel amplifier will get the job done for you. If you want to just create a better sound with your new speakers, then you can also use 2 or 4 channel amps. This is dependent on how many speakers you want to power. The more speakers, the more channels will give you max performance. If you want to do both subwoofers and speakers, then going with a 4,5, or 6 channel amplifier will do the trick nicely. The more equipment you want to power, the more channels you will need to get the job done.

As time has passed and technology has progressed, there have been many alternate forms of music to get our hands on.  Before all we could do was listen to the radio, either AM or FM.  Not much selection.  With the innovation of digital music formats, the possibilities have become endless.  Not only can you listen to the radio, but now you can pick up multiple channels with Satellite radio or HD radio.  Most in-dash receivers, not only double as a cd player with a radio, but also they have the capability of playing your digital music files.  Here is a little breakdown of the types of digital music you can use in your car stereo.

- MP3, WMA, or AAC-encoded CD-R/RWs directly on a compatible receiver

- Bring your portable mp3 player or iPod with you and connect it to your receiver by means of the appropriate connection form.  There are many different ways you can connect your portable mp3 players to each brand of cd receiver.

- Many in-dash receivers have the capability to use an sd card or memory card to play your digital music files.

- There are many external hard drives that can be used within a car stereo system that allows for a large amount of digital music to be stored on it.  This allows you to upload and listen to your music all the time without having to change cd’s or put more music on your mp3 player.

You can take your digital files right off your computer or however you receive your digital music and have it play in  your car in no time.  There are endless possibilities on how you can listen to your digital music files.  There are many accessories that allow most peripherals to be hooked up to brand name receivers in order to play digital music as well as the traditional CD.  Either way, its time to get in gear and go digital with your car stereo system.

For someone that’s really into music, choosing a head unit can be more difficult than choosing a car. If you haven’t been shopping for a new unit recently, it can be compared to going to a new restaurant for the first time and looking over a large menu of dishes you’ve never tasted. But if you’re a regular at the joint, you probably knew what you wanted before you entered the door. Likewise, if you’re a technophile, you already know what you want in a head unit and there’s little that I can say that will change your opinions or tastes. That’s what it really comes down to — since the advent of modern CD players, the differences are rarely performance related but rather functional and styling differences.

So what’s the scoop on choosing a CD player for a modern car audio system? There are about a dozen things that enter into the process. To each buyer, different things weigh differently in importance, even if we ignore right from the start the wild price spread that you’re likely to find. If you’re a first time buyer, you might want to take this list to the store with you and refer to it just to avoid overlooking something important in the “heat of the moment”.

First let’s consider how well the deck integrates into your car. Nowadays, most decks will fit most cars due to somewhat standardized form factors; however, there’s always the exception, so make sure that the deck is suited for your car and isn’t going to require major surgery to “make it fit.” You might want to consider the cosmetic integration, like does the lighting match the rest of your dash. Some decks have the ability to change color of their displays and some don’t. Does the deck look like it belongs or does it stick out like a “sore thumb?” Remember, theft is more likely if the deck screams, “Look at me.” On the other hand, perhaps you want to make a statement — either way, make sure to consider all aspects of physical and cosmetic integration. Also consider remote operation. If your car already has remote capability, will the new deck integrate with those steering wheel functions or will a custom approach be needed?

Consider the fact that the display is the only way the deck can communicate with you. What about the display? Can you read it in bright daylight? Just because it’s easy to read in the store doesn’t means a thing in direct sunlight, and many decks have displays that wash out in bright surroundings making them almost useless. On the other hand, if it’s a bright display, are you able to dim the display with the rest of your dash? Driving at night with a super bright head unit in the middle of the dash can actually create a driving hazard.

What about operator input to the deck? Does it have a jillion microscopic buttons, or can you actually operate it safely while driving? Do you have to press multiple buttons while holding your mouth in a certain position in order to scroll through useless menus in order to perform basic tasks? Does it come with a owner’s manual that is thick as a dictionary? If so, you might want to consider something a little more user friendly. I often like to relate the story of the time I was attending a trade show and one of the large manufacturers was showing one of their new decks for the first time. It was quite impressive and loaded with buttons, displays, and gadgets, and boasted the ability to do just about everything but make coffee. After the salesman had demonstrated the deck, I took a closer look at it and noticed that there didn’t seem to be an “off” switch. I asked the salesman how to turn it off and he couldn’t find the off button either. It seems that they had made it so complicated that they overlooked the off button and he had to “get out the book” to find the hidden menu that enabled the power down sequence. Believe it or not!

Another thing to consider is additional formats. Many folks want to be able to play MP3 discs which is understandable given the average driver’s needs. There are, of course, other considerations such as multichannel audio [surround] that might matter. Other format-related features to consider are compatibility with XM or Sirius Satellite Radio and the complexity of adding those features. These new radio options are becoming very popular and you might not want to be left out.

Features that allow system expansion are sometimes important as well. A sub output is a serious consideration. Nothing improves the sound of a car audio system like the addition of a subwoofer, and having a separate output to drive one is a really nice addition. This all-important feature adds little cost to the deck and should be considered in all but the most basic installs. The same can be said for a changer input — if you don’t have the long play capability of MP3, a changer is a good option. Be sure to consider this capability as well as if it’s the same port that might have to be used for satellite radio.

If you’re a radio fan, be sure to consider that cost and FM performance are seldom related and oftentimes some of the more expensive decks don’t seem to be great performers in this area. Personally, I believe in the “try before buy” method of testing a radio. Consider that a deck installed in a store demo board and hooked to a cable or giant antennae on the building roof might not represent installation in your car. If you’re an AM talk radio fan, you might want to take even more deliberate steps to choose your unit. Sometimes, in the quest to build “super” disc players, the AM radio section gets a back seat and is grossly neglected. A listen here is good advice and also consider that the switching power supplies in many large aftermarket amplifiers wreak havoc with AM reception — so let the buyer beware.

Now we get to the really juicy part. What about the “sound” of the deck? Technophiles fancy themselves in arguing about things such as the type of DACs and number of bits and a hundred other features. If that trips your trigger, then I say join in on the fun and confuse yourself with the rest of them. But if what you are really after is good sound, you can have it with virtually any kind of DAC or whatever kind of widget you’re likely to encounter in any modern deck. Speed related errors, frequency response errors, and excessive noise are non issues in modern digital formats, so sound quality is pretty much a non-issue as well. Sure, in many decks there are lots of “functions” that allow you to manipulate the sonic attributes as well, and if this suits your style then choose the features that appeal to you.

Even issues such as output voltage capability are not as big a deal as some think. Even the worst decks output more than 1 or 2 volts and virtually any power amp can be driven to full output with a volt or less. While it’s true that higher voltage outputs can help to minimize noise problems, good installation and proper wiring will go a lot farther.

And, finally, we get to the bottom line. What kind of reputation does the deck have? What about the warranty and support? Unless you’re filthy rich, or a bench tech, you might want to consider that even the best deck can have a problem. No amount of expensive parts and quality control will totally eliminate the occasional failure. How long is the warranty and what does it cover? Does it apply if you install it yourself?

I feel confident that if you consider the things I covered in this article that you will, with a high certainty, be able to choose a deck that you can be happy with.

On long road trips (when you are not driving, of course) or airline flights, having a portable DVD player can make the miles zoom. You can watch your favorite movie, listen to CDs, or bone up on that client presentation—all with a single device.

Best of all the technology has matured to the point where you don’t need to spend a fortune for a good unit. You can find a decent model with at a 7-inch or larger display for around $200. However, the range of features on these players varies. Some are optimized for game playing, while others are for movie viewing. Browse our list of suggested features and decide which ones are most important to you before you purchase. With care, you can end up with a portable player suited for business and pleasure.

 The Quest For Perfection

As with most technologies, you get what you pay for, and that concept applies to DVD players, as well. If you find a feature-laden machine at a rock-bottom price, expect that discrepancy to show up somewhere. Consider all our buying criteria (and ignore the media hype) before you make a selection. One more thing: Always evaluate the video quality of any machine before you buy it.

Battery life. This is a big issue for road warriors but one many of us take for granted. Look for at least two hours of battery life in video playback mode. Steer clear of the few portable players that do not have batteries, instead taking power from a wall outlet or car lighter.

Car kit. If you plan to use your DVD player in the car, purchase a model that includes a car adapter or offers one as an add-on. For maximum convenience look for a tablet model with a mounting system that attaches the player to the back of a vehicle’s seat.

Format support. Your player will support standard DVDs running MPEG-2 files, but look for added support; MPEG-4 ASP (Advanced Simple Profile), WMV9 (Windows Media Video 9), DivX, and XviD formats are bonuses. Support for CDs and MP3s turns your video player into a jukebox. If you burn CDs or DVDs, make sure your player supports writeable (CD-R, CD-RW, and DVD-R) formats.

Output jacks. Virtually all DVD players can plug into a PC or TV for large-screen playback. However, high-quality outputs (S-Video [Super-Video] for video; Optical Out for audio), will afford better playback quality.

Screen orientation. The more screen real estate, the better. (Not all players have screens, some are designed for use with another system.) A 7-inch screen is standard with many players, but a 10-inch screen makes viewing more pleasurable. If you’ll use the player in a group environment, a swivel screen will ensure that everyone gets a view.

Sound control. You won’t always be using headphones, so check the sound quality of the player’s built-in speakers. (Stereo is a must.) Make sure you can add external speakers, you may need a small pair for business presentations. Dolby Digital support is a given; for optimal quality, look for virtual surround sound, as well.

Weight. If you travel light, check the weight on any player you consider. Anything heavier than 5 pounds can feel like a brick after awhile. Don’t be fooled by size either. Some of the smallest players have overweight batteries.

Portable DVD Players are rapidly becoming the most widely used portable electronics used. Besides MP3 Players, Portable DVD Players are the most convenient and reliable source for entertainment when traveling. As the technology increases, players are getting smaller and more lightweight. This allows for better portability and convenience when on the go.

Portable DVD Players are getting smaller, yet the screens are getting larger. The average screen size is about 8″ but can span up to about 15″. There are so many styles to choose from that it will keep you busy just trying to find the right one for you. Luckily, we here at Overdrive Electronics make it simple for you. We give you the basics to help narrow down your decision.

Most players have a DVD deck with a built-in screen. Some flip up and some even swivel for more convenient watching. There are now tablet style portable dvd players that give a cool new look to the dvd player. Some portable dvd players can even be attached to a tv so you can watch a dvd without an actual dvd player. Most come with headphone jacks to give the viewer a personal sound. Some even have a few jacks to allow for multiple listeners. You should always consider buying headphones in order to keep the noise down when traveling because most dvd players come with built-in speakers. Some systems come with the headphones, but it is advised that you purchase a new pair of better quality.

There are now a lot of players that will play CD’s and MP3’s along with the original dvd. This gives you an all around better machine to allow you to accommodate different formats. You can also get dvd players that come with a built-in tv tuner, so you can choose either to watch dvd’s or the tv. Whether you get a small portable dvd player or large, you should always remember that you get what you pay for. Most portable dvd players that you can get under $50 will not last you long.