And so it came to pass, on 14-07-96 22:30,
   that Tyler Smith spake unto All :
 TS> im new in this field, but i really want to learn more about
 TS> it...here's basically what i know...if you have something to add or
 TS> see something wrong with what i have written, PLEASE let me
 TS> know...Thanks a lot
Okay... the FIRST thing you have to know is how much money you want to spend. 
 Without knowing that, you won't know how much to put into what components, 
or even what components to look for.  For example:
 TS> first, you need a reciever, a good one (like a CD player or tape
 TS> player for those of you technophobes...) it has something like 30x4
 TS> which is 30 watts to 4 speakers...
Personally, if I was going for a GOOD system and wasn't TOO limited in my 
budget, I'd get a deck that has preamp outputs only, and use external amps 
exclusively.  The deck will cost about the same as one with the built-in amps 
(which says a lot for the quality of said built-in amps) but the separate 
amps will add a fair bit to the cost.  
It's very rare to find a deck that really, truly has POWERFUL, QUALITY 
internal amps.  There are some amps rated 30x2 that are larger than a deck 
that claims to stuff 30x4 in along with all the radio, tape and CD hardware.
 TS> i think...then a .5 to 2 volt pre-amp (i'm not sure what this
 TS> does...or what it matters)...that will either run straight to your
 TS> speakers or to an amp...
Something like this is typically used to boost the signal level going to an 
amp, which lessens the amount of noise in the final output.  Specifically, if 
noise is going to get into the lines between the head unit and the amp, it 
will be the same level whether the signal is .5V or 2V.  With a 2V signal, 
however, the signal is relatively much higher than the noise, so the noise 
becomes less of a factor.
This is really only a concern in higher-end systems; line drivers are a 
relatively expensive add-on for what little NOTICEABLE difference they make 
in most systems.
 TS> the amp, say 50x2 will put another 50 watts to 2
 TS> speakers...(presumably now the total to two of the speakers would
 TS> be 80 watts...)  
Wrong.  Power is not cumulative, and no amps in existence will take the full 
30W input (there are technical reasons why a deck couldn't drive 30W into an 
amp anyway -- wattage depends on the impedance of the load; do some reading 
on Ohm's Law).  
Some amps have "speaker inputs" but those have resistors inside that drop the 
level down to something the amp can handle.  These tend to induce more noise 
in the amp anyway; the best bet is to use line-level outputs on the deck to 
run directly into the amp's line inputs.  
BTW, line drivers (your .5V-to-2V boosters) are useful ONLY on line-level 
signals anyway.
 TS> the speakers are woofers, mid-ranges, and tweeters, i think...like
 TS> 6x9's would be 6 inches by 9 inches i think...say for the
 TS> woofers....
Yes they would, although they're generally not recommended for high-end 
systems; their shape is far from "friendly" when it comes to accurate audio 
reproduction.  6x9s are an abomination designed to squeeze more speaker into 
wide but shallow rear decks of most cars in the 60s and 70s.  For a quality 
system, you're likely going to be doing a custom mounting job anyway, rather 
than just bolting them into the car's existing cutouts, so there's little 
point in wasting your money on 6x9s.
 TS> then you have sub-woofers that would usually take another amp (or
 TS> you could take the one off your speakers to power the subs..., say
 TS> 8', 10', 12', 15', or 18's...) the higher the watts, the louder the
 TS> hit of the subs....(if you like that sort of thing...) 
Sort of.  It also depends on the sensitivity of the subwoofer *system* (which 
consists of the driver, crossover and enclosure).
 TS> now, i've heard of a 'cross-over' but don't really know what it
 TS> does...
A crossover separates the full range of audio frequencies into smaller 
"bands" that can then be sent to speakers that are better designed to handle 
audio in those certain bands.  There are typically two types of crossovers; 
passive, which go between one amp and several speakers; and active, which go 
between the signal source and multiple amps.
My best advice would be to go to the library and check out some books on 
audio basics and design.  Look into some of the numerous car audio magazines 
available out there as well (Car Audio & Electronics, Car Stereo Review, 
Autosound & Security, and Petersen's Autotronics are among the more 
wide-spread and easiest to find).
IKEA ... Swedish for "particle board."
--- Sqed/32 1.10/unreg
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