Beginners Guide
Welcome to the Beginners Guide to In-Car Audio. This section of the site is here to help explain the jargon that is associated with headunits, amplifiers and speakers.
Sat Nav
Transferable Navigation Systems
Transferable Navigation Systems have advantages over Fixed Navigation Systems and Vice Versa, horses for courses is the old adage. Transferable Navigation Systems can be taken from car to car and are normally powered from a vehicle’s cigarette lighter. The unit’s themselves are typically installed with a device that fixes to the car’s windscreen or dashboard allowing visibility to GPS Satellites. Some Transferable Navigation Systems can be connected to an optional External GPS Antenna which fixes to the outside of the vehicle and gives the system maximum exposure to satellites. This ensures optimum positioning accuracy when navigating.
Transferable Navigation systems are not as accurate as Fixed Navigation Systems as they only use GPS data to determine your car’s position. Fixed Navigation Systems on the other hand use a blend of GPS, Gyroscope and Speed Pulse data that allows the navigation software to accurately calculate your vehicles position even when travelling through tunnels, areas surrounded by buildings and other locations where a GPS Signal cannot be received.
TMC Traffic Message Channel is readily available on Fixed Navigation Systems and is sometimes included as standard. TMC gives you FREE real-time traffic information that can be used to avoid traffic jams and other road hazards, Dynamic Navigation options can also offer you an alternative route when an incident is identified.
Fixed Navigation Systems
Fixed Navigation Systems have advantages over Transferable Navigation systems and Vice Versa, horses for courses is the old adage. Fixed Navigation cannot be taken from car to car, the units are usually installed in place of the car's radio which is then replaced with a motorised screen with full mapping in 2D or 3D or a car radio that includes navigation these are known as Turn by Turn systems, getting the name from the instructions both visual and vocal from the system, the last type may have a stand alone screen on the dashboard that can be connected to a full Navigation system which remains in the car while the screen can be removed from the vehicle . Visibility to GPS satellites is generally via GPS receiver being placed on or underneath the dashboard or lately some install external GPS receivers on the roof (you may notice Mercedes, BMW etc with a Shark Fin rear aerial). Transferable Navigation systems are not as accurate as Fixed Navigation systems as they use GPS, Gyroscope and connection to the Speed Pulse of your car, allowing the user to be accurate in position even when driving through a tunnel. Fixed Navigation generally are higher specified than Transferable Navigation, the systems work faster as they have higher processing power, many have Touch Screen which allows for speedier instructions to the Navigation unit, 7 Digit Postcode search can bring you to within 60 homes with the press of a few buttons and generally far more detail in Points of Interest and Map Detail. When you enter your destination and then put in the house number the system will even tell you which side of the road that your destination is sited. TMC Traffic Message Channel is readily available on Fixed Navigation systems, sometimes as a FREE included option, this gives you real time traffic information that can be used to avoid jams by using the Dynamic Navigation option.
iPod Connections for Cars
Manufacturer Specific iPod Connecting Boxes
Many manufacturers now offer a connecting box that seemlessly integrates an iPod with their head-units that support CD Changer Control. When the iPod is plugged in, you are able to scroll through playlists and songs using the buttons on the stereo - allowing you to easily and safely select the song that you wish to hear. The connecting box also displays detailed song information on the stereo and charges the iPod's battery when it is connected.
iPod Connecting Kits for Original Factory Fit Equipment
A range of iPod connecting kits are now available for original factory fit stereos. Functionality is similar to the maufacturer specific iPod connecting boxes descibed above.
CD Changers for OE (Original Equipment)
We stock a range of CD multichangers that, when connected with a smart lead, will allow your original factory headunit to operate a CD multichanger. This equipment will show large savings compared to car manufacturers' prices, everything you need to connect the changer is included in the kits.
MP3
What is MP3?
MP3 is just a method of compressing files. Its name is an abbreviation for the much more unwieldy MPEG (Moving Picture Experts Group) 1 Layer 3. All you really need to know, though, is that MP3 files are about one-tenth the size of uncompressed audio files. On a CD, each minute of music takes up about 10 megabytes of space. Very few people would want to download a 40-megabyte file just to hear four minutes of music. With MP3 compression, the same four-minute song would take up about four megabytes, and would sound almost as good as the original, 40-meg file. Four megabytes is still significant, but is a practical size for sending over the Net, especially for those with fast connections.
How Can I Play MP3's?
Even if you have never installed a special player, you can probably play MP3 files on your computer right now. The Media Player that comes with newer versions of Windows, or QuickTime 4 for Macintosh, work just fine. However, Windows users may wish to download the industry-standard Winamp. This product used to be shareware, but is now completely free, and its added features make it worthwhile.
Where Can I Find MP3's, and How Do I Get Them?
The easiest way to obtain MP3 files is to encode your music CD's into files for your computer. There are various programs that do just this, the MP3 tools section of download.com is home to many of these. Another way to begin an MP3 collection is to download MP3 files from other people, kazaa is a popular file sharing program rather like "napster", allowing you to search for MP3's and share your own.
How can i play MP3's in my car?
Caraudiodiscount.com offers many MP3 compatible headunits and CD autochangers, look out for "MP3 Playback from CD-R/RW" in the product's title. Once you have an MP3 compatible product installed, it is possible to play hours of MP3 files that have been recorded onto a blank CD-R/RW by your computer. Click here to visit the MP3 Headunit section.
Head Units
Head-Unit
The technical name given to the car radios. In Europe, we use the standard size of car stereo unit known as 'DIN'.
Automatic Volume Control
A useful feature that is found on high end head-units. Some have a microphone that 'listens' to the background noise and some are connected to the car's speedo. This feature prevents the music from becoming inaudible against rising background noise as you speed up.
Autostore
The radio will 'read' the airwaves and then store the most powerful radio stations in its presets ready for easy selection.
Balance
Moves the sound to the left or right speakers, to help get the best stereo effect.
Fader
Rather like the balance control, however the fader moves the sound between the front and back speakers.
Detachable Face
Sometimes referred to as 'Removable Panel' or 'Theft Deterrent Faceplate', or some variation. This is a recent physical method for foiling thieves. The idea is that you take just the front bit with the buttons away with you. A thief cannot buy a new face for a back which he may have pinched unless he has a retail receipt for it. Kenwood makes sets with rotating faces called Mask.
Loudness
When played quietly, we perceive bass frequencies to be less prominent. At low volumes, you hit this button and it all sounds richer and fatter.
MASH
Multi-stage noise shaping. This is the name given to the digital advances that were introduced after the CD specification had been established.
Oversampling
A digital electronics method for the CD machines to be absolutely certain that the information they are playing will play as music.
Pre-Amp Output (Pre-Out)
A set of leads, usually of the RCA or phono type, that extends from the back of the unit, allowing connection to an external power amplification system.
RDS (Radio Data System)
Extra information broadcast on FM along with the music that is displayed with an RDS enabled head-unit. Some will hunt down certain types of programme for you, or even traffic reports. The latter feature is only available on RDS-EON enabled head-units.
Amplifiers
Bridgeable
This is where two amplifier channels can be combined to give one meatier version, for example, to run a big bass speaker or use a 4-channel amp as a more powerful 2-channel version.
Crossover
Can be confusing. There are two types of crossover, active crossovers and passive crossovers. Both separate the bass frequencies from the mid and treble frequencies and send the right signals to the right speaker.
MOSFET
A type of amplifier power transistor (the 'engine' of the amplifier), thought to be so good that the manufacturers will generally print the fact on the outer casing of the amplifier.
RMS
Stands for 'Root Mean Square', which refers to the output power of an amplifier in watts. Although it should really be qualified by stating the RMS value in relation to the music, i.e. '20 Hz to 20kHz, 4 Ohms', this is the single most reliable rule to use when comparing the wattage of amps.
Signal To Noise Ratio
An expression to give you some idea as to how 'hi' your 'fi' really is. A reading of 90dB is a lot of signal for a little noise (hiss) and will always indicate a good piece of kit. Higher than this and your talking special. Also applies to any audio unit of any kind.
Speakers
Bass Reflex/Ported
A bass enclosure with a hole in it. The hole is usually in the form of a piece of tubing sunk into a wooden box, and has dimensions calculated to give you the deep stuff from the back of the speaker, as well as the front, without canceling itself out - in fact, offering up to twice as much bass as without.
Coaxial/Triaxial/Component
Coaxial refers to a design of speaker where the tweeter is mounted in front of the bigger speaker as a single item. Triaxial is a design where there are there are two smaller speakers mounted in front of the bigger speaker. Component is the situation where each speaker is a separate item. The coaxial and triaxial designs may be called 'full range'.
Dual Cone
Method used on cheap speakers to enhance the high sounds from a single cone.
Midrange
Speaker that handles the middle frequencies - where most vocals actually occur.
Tweeter
Littlest speaker that deals with the high frequencies.
Woofer/Subwoofer
Speakers for bass, from 8 inches to 18 inches in diameter.
