|
What is a Head Unit?
Your best source for the latest in car, truck and boat audio, video and extreme undercar lighting systems and accessories. Factory authorized distributor for PlasmaGlow, Pyle Video and more!
Go to Web Site
|
|
|
|
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.
Please note that the remote wires for stock (OEM) radios will be of a different color (probably not blue).
|
|
|
|
|
Copyright © 2003 - 2008 URL.biz. All rights reserved. |
|
