Spare Tire Subwoofer Question

I have a Mazda P5, it has one of those subwoofers in the spare tire, what does the switch do that says "phase" then theres a normal or reverse option, Right now its on Reverse, im just wondering what it does

It reverses the positive and negative connections to the subwoofer. It has a small affect on how the bass blends with the front speakers.

If you were playing a 40Hz tone it would look like a sine wave right? Now if you reversed the phase, it would make it a cosine wave. If all the speakers were the same distance from your head you would want everything in-phase. If you were to reverse one of two speakers that were the same distance away, the waves would cancel each other out and you would hear significantly less sound. Since the subwoofer is farther away from your ears than the speakers, fewer frequencies may become canceled out if you reverse the phase...or not.

The affect of the phase switch is very minimal but play around with it and see if you can find what sounds best to you.

Alright, since this thread isn't going anywhere else and I have questions that fit well under the topic described in the title, I'm going to hijack this thread.

Here's what I'm planning on doing in my 2003.5 P5: Installing a 2-channel amp and new front speakers and using a tri-way crossover (and the amp's tri-mode capability) to connect to the stock sub.

My questions are the following:

1. The car has factory tweeters. How are they wired? If I run speaker wire from the amp directly to the new front speakers (sans wiring harness) will the tweeters still get a signal?

2. How should I wire the sub? Since the sub has a built in amp, is it bad to have the signal go from the HU->Amp->Sub? Will the input signal (coming from the new amp) to the sub be too much for its built-in amp? Also, I know I can just splice into the existing speaker wire that currently runs to the sub, but how can I replace the speaker wire running to the sub since the sub signal runs through a wiring harness? Can I simply pull out the speaker wire running into the harness and jam the new speaker wire in (notice the highly technical terms of "pull out" and "jam").

Any help is greatly appreciated. I should also put a big "Thank you!" out there already to all the people who have posted all this valuable information about P5 already. Just reading through all these threads prompted me to install the amp and speakers myself instead of paying out the ass to have someone else do something that is actually very simple. Thanks!

do not tie an amp into the stock sub! it is self-amplified, and optimized for it's own performance, you willnot be able to squeeze anythign else out of it. THe stock sub uses what's called speaker-level inputs meaning it takes the stock speaker level voltage and uses that as signal. sending it more signal will only freak it out you willnot gain any output and you will most likely push it to clipping and beyond. Amplify your front speakers, this is good, but just do that, tri-way is an annoying selling gimmick that should be burned. If you want to hav emore bass, you're gonna need a different sub, period. If that's the case, it'd likely be just as inexpensive, and MUCH MUCH les sof a hassle to just get a seperate sub amp.

Oh, and to answer the tweeter question. they're wired inline with the stock front speakers. assuming you tap into the speaker wires from behind the deck, then you'll get everything you need there.

Mostly, before you really do anything, I'd take a step back, and evaluate what you're trying to achieve and attempt to determine if you're on the right route.

Thanks for the input! I thought these things might be the case, but needed verification from someone.