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Car radio, help wanted.
Chippy - 31/12/06 at 10:50 PM

Hi, recently was given a new radio without any fitting instructions, and need to find out a couple of things.
1/ It has two leads which are marked RCA line out left, and line out right. What are these for?
2/ The set is marked as 4 x 7w, I assume this is the speaker output. All the speakers advertised have ratings of way over this, does that matter?
3/ When fitting Tweeters, are they wired in with the other speakers, or do they need to be on seperate outlets?
Pretty dim at electrics, sorry, any help greatly appreciated. Thanks, Ray

MikeRJ - 31/12/06 at 11:01 PM

quote:
Originally posted by Chippy
Hi, recently was given a new radio without any fitting instructions, and need to find out a couple of things.
1/ It has two leads which are marked RCA line out left, and line out right. What are these for?


They are low level outputs to drive an external amplifier.

quote:

2/ The set is marked as 4 x 7w, I assume this is the speaker output. All the speakers advertised have ratings of way over this, does that matter?


No it doesn't. The speaker ratings should always be higher than the head unit output rating. However, the majority of power ratings in car audio equipement are pure bullpoo anyway, unless you are spending a lot of money

Contrary to popular belief the power rating of a speaker does not indicate how loud it will sound with a given input, indeed quite often the higher the power rating the lower the efficiency, hence lower sound pressure for same power input.

quote:

3/ When fitting Tweeters, are they wired in with the other speakers, or do they need to be on seperate outlets?


Tweeters must always be driven via a crossover that separates the high frequencies from the mid/bass ones. Driving a tweeter directly from the headunit would blow it very quickly.

Most cheapo tweeters have a single capacitor soldered on the back to act as a crude crossover. This will normaly be connected directly to the head unit output (i.e. in parallel with the mid/bass driver).

[Edited on 31/12/06 by MikeRJ]

Chippy - 31/12/06 at 11:14 PM

Hi Mike, thats great, knew that somebody on here would have the full SP. Many thanks, Ray