the dash) to an MP3 (I can blame this entirely on Nigel.e's influence) . And
holy crap the factory power wire to the stereo is so small. So for those of us
who like it loud, running a bigger wire (with new fuse!!!) from the ignition
is not a bad idea. For the less techo of us, this is just so the voltage can
keep up with the high demand of the stereo when played loud, so you don't need
to rush out and get your car rewired, it's perfectly safe as it is.
So for those who want to know more, what it means is... When you change the
car stereo from a factory one, it probably (one would hope) has a higher power
rating, this is the 50Wx4 you see on the front of most car stereos now.
Forgetting if it puts actually puts out 50W or not, the higher the power of
the amplifier the more energy (current) it will require to make it run well.
If the power cable is too small it puts too much resistance to the flow of the
current, and as the car has only a 12v system the voltage at the stereo will
drop resulting in less volume and quality (which is why we bought the bigger
stereo in the first place). But don't worry the small wire will not hurt the
car or stereo, just gives less performance. For those not bored yet... what's
wrong with you??? anyway for example, say the car stereo needed two amps (the
current=I) at 12v to perform it's best and the little wire has one ohm
resistance (this is R) (and one ohm is not much).
Ohms law of electricity states that V=IxR
So if we need 12v but there is a resistance in the line of 1 ohm
Then V=1From V=2amps x 1 ohm
This means that because of the resistance in our wore we lose 2 volts to the
stereo, so we only get 10v at the stereo and we are nearly 20% down in
performance. this is why you see all the young guys (and me, still young,
maybe, your only as old as the woman you feel).. they all have huge cables
going to their sub woofer amplifiers, as they draw large currents and a small
resistance will drop the volume and quality considerably.
Sorry if confusing, I hope it may be interesting for some. I'll probably get
critiqued to hell, but please remember it's a simple example.
Again if your not a techo and all this means nothing 'don't worry' it will not
harm your car at all, as the normal wire has a fuse to protect it.
Gazza
Gazda in the white HOT Mazda 
