anything about car audio and electronics...

[sHoCkAbSoRbEr]

hi. i'm actually a newbie and don't know anything much about setting up car audio system... could anyone help? :wink:

to start with--- ? :oops:

[x-wind]

head unit (car stereo mo)

[sHoCkAbSoRbEr]

k, salamat ha... :oops:

[sophia2000]

you could try this site. very informative

http://www.eatel.net/~amptech/elecdisc/caraudio.htm

[sophia2000]

Head Unit:
The term head unit will be used instead of radio or tape deck or cd player or... well you get the point.
Power Connections:
Most head units have 2 power input connections that have to be connected to a 12 volt source. The 'battery' or 'memory' wire has to be connected to a constant source of power (has power on it at all times - even when the ignition switch is in the off position). The other power wire (the 'ignition' wire) is connected to a power source that's controlled by the ignition switch and therefore will only have power on it when the ignition switch is in the 'on' or 'acc' position.
Speaker Outputs
Most head units have outputs that are designed for driving 2 to 4 speakers. These outputs provide the audio output power to drive the speakers. The power output from a high power head unit is limited (by battery voltage) to approximately 20 watts per 4 ohm speaker. All of the manufacturers that say their head units can produce 30 or more watts of real power are... how can I say this? Hmmm... Full of it!
Note:
On "high power" units, the internal audio amplifier will be instantly damaged if a speaker output wire is allowed to contact anything except a speaker terminal, even if the volume is not turned up. Be sure that there is no power to the unit when making any connections. This link explains why the outputs will be damaged if they contact ground.
Preamp Outputs
Preamp level outputs are audio outputs that are used to drive an amplifier (or equalizer or crossover...). Preamp level outputs do not have enough output current to allow them to drive speakers directly. They are generally included on higher end equipment. In virtually all cases, they will have RCA type connectors. Some units will have only one set of preamp outputs (would likely be a 'rear' output). Other units have multiple pairs of outputs for front, rear and subwoofer signals.
Remote or Power Antenna Output
There may be one or more switched 12 volt outputs on your head unit. These outputs are usually called remote outputs. They are used to control power amplifiers or power antennas. If your unit has only one remote output, 12 volts will be sent through it when any audio source is being used (tuner, CD, tape, aux...). It will be 'hot' (have 12 volts on it) when the head unit is on. It will have no voltage when the head unit is off.
If the unit has two remotes, one wire (generally a dark blue wire with a white stripe* for aftermarket radios) will be for your power antenna and will only have 12 volts on it when you are using the tuner. It will have no voltage on it when the head unit is switched to CD, tape, aux or is switched off. This is so that your power antenna will go down when it is not needed. The second output (generally a dark blue wire* for aftermarket radios) will be marked amp remote (or amp turn-on) and will have 12 volts switched to it when any source is in use. The diagram below only shows a single remote wire. There is a diagram on the test light page that shows both types of outputs.
Please note that the remote wires for stock (OEM) radios will be of a different color (probably not blue). You can refer to the following page for the color code for your vehicle.
Street Dreams
*Some radios use blue with a white stripe for the power antenna and others use it for the amp turn on wire. Just keep in mind that if it has 2 dark blue wires and one has a white stripe and the other is solid blue, those wires are for amp/power antenna control. You'll have to refer to the deck's owner's manual for the color code.

Again with the fuse thing...
Most remote outputs are switched through a very small transistor. This means that they are EASILY damaged by excessive current flow. They should be fused close to the head unit with a .5 amp fuse. A 1 amp fuse may not protect the switching transistor, which supplies power to the remote output. Do not try to use the remote output to power fans directly.

Stock/Factory/OEM Head Units:
If you have a stock head unit and don't want to replace it, you'll likely need to use a Line Output Converter (LOC). It will convert the speaker level signal to a preamp level signal. Many times, the LOC is connected to the speaker wires that feed the speakers in the rear deck (parcel shelf) of the vehicle (especially when the LOC is going to be used to drive an amplifier which is going to drive a subwoofer). If the system is going to use multiple aftermarket amplifiers for front/rear and subs, you'll use 2 LOCs and they'll be installed behind the head unit. If your head unit doesn't have a built in amplifier (it would have amplifiers elsewhere in the vehicle), you'll have to connect the LOCs to speaker wires (after tha amplifiers) wherever you can get to them. For vehicles with special 'systems' like the Bose© system, you may need a special adapter. PAC makes both LOCs and system-specific adapters.
Speaker Output Clipping:
If you use an LOC, you will have to set the gains on your amplifier so that the amplifier reaches full power before your head unit's volume control reaches 1/2 volume. Most radios' speaker outputs will start to clip at about 1/2 volume. This is far earlier than the point where the preamp output signal starts to clip on most radios. The only time that I've seen a preamp out start to clip along with the speaker output is when the preamp output signal is derived from the speaker output via a voltage divider network (sort of a cheap internal LOC). This is usually only done on the bottom_of_the_line head units.

If you blow a fuse when installing your head unit, consult your owner's manual for the proper replacement fuse size. By proper size I don't mean physical size. I mean amp rating. If an electronics manufacturer specifies a certain size fuse, they do it for a good reason. They know what the equipment and internal electronic devices can handle. More than half of the head units that I serviced would not have been damaged if the proper fuse would have been used.

TECH TIP:
Speaker Connections
If you are not using your speaker output wires, cut them off so that there are no copper strands sticking out of the insulation AND tape up or otherwise insulate the end of the wire. You may be able to pull on the insulation so that it stretches over the end of the cut off copper wire.
REASON: If the speaker wires on a high powered radio are allowed to touch to any grounded piece of metal, the head unit's internal amplifier will be instantly damaged (even if the volume is not turned up).
RCA Cables
Do not allow any source of power (12 volts) to come in contact with the shield (outside metal part) of the RCA cables.
REASON: The shield is grounded to the case of the head unit. It is the reference for the preamp audio signal. If it comes in contact with a source of power, the ground connection inside of the head unit will be damaged. This may cause lots of problems including blown tweeters, engine noise, lack of bass and many more.

Aftermarket Wiring Harnesses:
When installing an aftermarket head unit, you should not cut the factory plug from the vehicle's factory wiring harness. Instead, you should buy an aftermarket wiring harness that would plug into the factory harness. These harnesses (such as those made by Metra) will have each wire marked with it's function (ignition, battery/constant, speakers...).


Amplifiers:
A power amplifier takes an input signal, usually a preamp level signal, which has both low current and low voltage characteristics, and produces an output which will have higher current and voltage levels. The power supply available to the audio output IC in a head unit is limited to the battery voltage of the vehicle. This means that the head unit can produce an audio signal with a limited (by the battery voltage) voltage swing, and therefore a limited power output to the speaker. Most amplifiers have a special circuit (switching power supply) to boost the available battery/charging system voltage to a higher voltage. The higher voltage developed in the amplifier's internal switching power supply will allow the audio output voltage swing to be greater. This allows the amplifier to produce more power into the speakers connected to the amplifier's output terminals.

Gain Controls:
Most amplifiers will have some sort of level or "gain" control. This control is used to match the output of the head unit to an amplifier. The maximum audio output voltage from different head units will vary. If there were no gain controls, some head units would not be able to drive the amplifier to its maximum power level. Other head units may drive the amplifier to full power at a fraction of its volume control's range. More gain info can be found on this page.

Note (rant):
There have been many people who have said that the gain controls were not volume controls and they are right, to a point. Some amplifiers' gain controls are used precisely like a volume control (one end of the potentiometer connected to ground, the other end connected to the pre-amp signal and the wiper connected to the amplifier's front end). This configuration will allow you to reduce the output to nothing at the minimum gain position. These are not very common but they HAVE been used on some amplifiers. I know because I took the cover off of a few amps to see why they had absolutely no output (Doh!). Others are connected similarly but there is a small amount of resistance between ground and the formerly grounded terminal of the potentiometer. This small resistance prevents the gain control from reducing the output to zero output. These are very common on amplifiers made in Korea and China. There are other amps that use the potentiometer to pull the signal toward ground. The pot is the lower half of a voltage divider and may use only 2 legs of the potentiometer. This type of gain control was used on at least one brand of Japanese manufactured amplifier. You can also put the potentiometer in the feedback loop to control the overall gain of the amplifier. The point to all of this is... There are many ways to use a potentiometer to control the output of the amplifier. Some are used precisely as volume controls and others are not. You can not make a blanket statement such as 'gain controls are not volume controls'.


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Battery, Ground and Remote Connections:
Virtually all amplifiers have battery, ground and remote connections which must be connected for the amp to operate. The battery connection is the high current +B source that's connected to the battery via a properly fused wire. The size of the power wire is determined by the current the amplifier draws and the length of the wire (from the battery to the amplifier). The ground is another high current connection and is connected to the chassis (body/floor pan) of the vehicle. The ground wire is typically as large as the power wire. The remote connection is a low current control input that tells the power supply of the amplifier to power up.

Remote Input Current:
The remote input current for amplifiers varies with the amplifier and the model. Some draw minimal current. Others draw a little more. The upper limit of a properly functioning amplifier is approximately 50ma (0.05 amps). If you're using/controlling more than 2 amplifiers, it is (in my opinion) much better to use a relay to control the amplifiers. Actually I really prefer having a relay in the remote circuit (no matter how many amplifiers I'm using) because it protects the head unit's remote output circuit in case of a short circuit. The following chart shows the remote input current for various amplifiers I had laying around the shop.

[N3IL53N]

very well said........

[kedeka]

try this site too

www.the12volt.com

[wrecker]

you could try this site. very informative

http://www.eatel.net/~amptech/elecdisc/caraudio.htm

very good advice, dyan din ako nagsimula sa site na yan

[wrecker]

try this site too

www.the12volt.com

ok din to a...

[dongkoy]

hello po,
im new po sa site na ito hope you could help me. gusto ko po sana malaman ang wiring color code ng toyota innova. kasi po gusto ko po sana manually replace yung stock carstereo ko ng sony dvd player kaso eh nawala yung owners manual ko. hope you could help me. thank you