I need help with my car audio system?

Question

I'm looking at the Alpine MRD-M605, and 2 Alpine trype R 12" subs. the amp is 600watts rms x 1 @ 2ohms or 400watts rms x 1 @ 4ohms which would be better? subs 2 ohms or 4 ohms I want 2 of the amps one for each sub.the subs power handling is 500watts RMS and the peak power is 1500watts. I also need to know what type of capacitor to get for it?

I have a 2002 VW jetta with a monsoon sound system. I need to know how to keep the interior speakers amped with the factory amp when i change out the head unit, and install the system? Is it possible to run the 3 amps in a head unit?

Answer 1

You get better sound quality and a longer lasting amp when loading an amp at 4 ohms but you get more power with 2 ohm.

It's a trade off. Besides, the subs can only handle 550 watts RMS so 600 watts RMS would be too much.

If your total system power is more than 1000 watts RMS you will need to:

1. Upgrade the alternator to a high output alternator
2. Upgrade to a heavy duty deep cycle battery
3. Upgrade the "Big 3" - that is to replace the power wire between the battery and alternator and the ground strap.

Failure to do this will result in you replacing them anyway as the alternator will eventually fail.

Here is a guide that will calculate what size alternator and power wires you need http://www.datafilehost.com/download.php?file=6d26c621

You'll need Microsft Excel to use it.

See my site for more info http://spkrbox1.spaces.live.com
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In rare and circumstantial cases, a cap actually helps. I can say this with full confidence as I'm running one in my car an have seen a definite change using an oscilloscope to test the theory.

In my case, my electrical system had a 4 volt gain in the whole drop out when a significant bass track was played using a the cap as opposed to not using it.

My specs:

alternator: 75 amps
audio system: 400 watts RMS (total)
cap: 1.5 Farad
current draw of accessories in car: 30 amps (total, everything on except audio system)

Somewhere in these numbers lies the truth to my success, I'm working on a formula to find this. The problem is no two cars are the same as I've added fog lights to my car which changes things from stock. So there can never be an "all-around" method to determine the usefulness of a cap. So the formula I come up with will be just for my car.

I'm also running a few experiments of my own to determine if a cap also increase the life expectancy of the audio equipment as well.

But yes, it's 0.5 Farad for every 500 watts.

Answer 2

I would go with the 4 ohm version of the subs. The amp will sound better with a 4 ohm load. You will not gain that much volume with an additional 200 watts, you'll probably be reaching the mechanical limits with 400 watts anyway. It's not worth the extra risk to run the amp at 2 ohms in your case.

When it comes to the cap, I agree with sparky. Make sure you upgrade the big 3 wiring and the battery before you think about a capacitor.

As far as your factory amp, Scrap It!
It is too much of a hassle to intergrate into the factory amp. Buy a 3rd amp to power your front and rear speakers. A nice 50 watts x 4 at 4 ohms Alpine unit would work quite nicely. You can still use your aftermarket head unit to supply an audio signal to your amps. I am going to guess that your HU has2 sets of RCAs (one for front and one for the sub/rear). You can just use a "Y" adapter to split the sub RCA into 2 sets.

Answer 3

Addressing only the Monsoon questions: I've found with Volkswagen Monsoon systems you can easily integrate the factory amplifier just by wiring up the new CD player like any other car. The Monsoon amp is designed to take high-level inputs and it has a current-sensing turn-on, so you don't even need to connect an amp turn-on wire.