Recently I replaced the rather embarassing Panasonic cassette tape player in my Mercedes 190E with a new sony CDX-GT270 front loader head unit. I was concerned to find that the wire harness supplied with the sony unit did not look exactly like the Panasonic’s harness and my enquiries at the electronics shop were met with an attitude of “if you have to ask you really should get someone else to install it for you”. But it only required a little research (just to err on the side of caution) and I managed to get it working and save myself a little cash too.
The process was pretty simple in fact, all I needed to do was:
1. Disconnect the negative terminal of the car battery
2. Slide the Panasonic cassette player out of the console using the release keys
3. Cut the wires off the old Panasonic harness one by one and crimp them onto the matching colours on the sony harness
4. Plug the harness into the sony head unit and connect the antenna
5. Slide the sony unit into place
6. Reconnect the car battery
I can’t believe I almost paid someone else to do it. You don’t even need to know exactly what colour wire does what, but for the sake of being thorough – the car audio wiring standard is as follows:
white : front left (+)
white/black striped : front left (-)
grey : front right (+)
grey/black striped : front right (-)
green : back left (+)
green/black striped : back left (-)
purple : back right (+)
purple/black striped : back right (-)
black : negative / ground
blue : antenna up/down
red : igntition (+)
yellow : battery (+)
blue/white striped : AMP on/off
Useful car audio links:
Sony XR4950X Car Stereo Installation
Home and Car Audio Answers
Download Sony CDX-GT370/s CDX-GT270/s CDX-GT160/s manual
Download Sony CDX-GT370/s CDX-GT270/s CDX-GT160/s installation
An introduction to the amps!
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= Amplifiers take the signal from the main unit and is large enough to be able to drive the speakers. It is preferable to use separate amps for high and low frequencies, but not necessary. The problem with the use of an amplifier for all frequencies is that you can adjust the levels between the different frequency ranges as easily as you can adjust the outputs of separate amps. Many people start their system with an amplifier to frequncies low (bass) and use their head units built-in power for the speakers at higher frequencies. This approach is appropriate, but an integrated power unit is usually not strong enough to listen at high volume and not clean enough for the most demanding ears. There are many options when choosing an amplifier.
power?
There are different ways in which power is measured by amplifier manufacturers to believe that their amps have more power than others. The laws of physics tell us that power can be obtained by multiplying current and voltage. For example, if the amplifier is 2 volts and 20 amps is based, then the power would be 240 watts, right? Not exactly. Globally, real 
amplifiers waste 50% or more of power in the as heat. This leaves you with only 20 watts. <
= “text-align: justify”> What do something more complicated than that. There are different ways to measure power. Power can be measured up and down the signal (Peak, or Max, etc.) Another way of measuring the power is equal to zero in the upper half (usually called the power of music.) The most accurate way to measure power is RMS (Root Mean Square) watts. The effective value is obtained by squaring the value of the signal, taking the average, then the square root. This is equivalent to the power actually delivered. Most reputable manufacturers use the RMS rating.
to get the RMS peak power or just divide by three. Power Music is only half the peak power. For example, an amplifier has an output of 00 W (peak) per channel. The power of music itself is only 50W per channel. RMS power is 33W per channel. There is a difference, right? Be careful when checking specifications of amps before buying, to see what you’re really getting. Formalize RMS power amplifier. <
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