2008 mazda 3 dimming

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=96371
Printed Date: May 05, 2024 at 9:01 AM

Topic: 2008 mazda 3 dimming

Posted By: lilkwazy2
Subject: 2008 mazda 3 dimming
Date Posted: August 13, 2007 at 3:51 PM

Hi everyone, I know this problem is cliche however given my circumstances, I don't believe it's a duplicate post so I'll just keep my fingers crossed that this doesn't get deleted lol.

Here's my situation, I just bought a brand new 08' Mazda 3 and all I've installed is a 2 channel line-out converter to RCA, connected to a 2 channel MTX 8302 amp, and a 12" sub in a sealed enclosure, keeping my stock headunit. THe line-out converter is getting the signal from the rear right and left signals of the headunit, the amp is connected to the battery via 4 gauge amp wires. I have completed 2 steps out of the Big 3, the only thing I haven't done yet is added a new wire from the + alternator terminal to the + of the battery. Since this car is less than 3 weeks old, and has a new alternator (I'm guessing 65amp), I can't seem to figure out why my headlights would be dimming because the MTX amp bridged in 4ohms does only 425watts @ 14.4 volts (not sure if that is even RMS) and it shouldn't require a high-output alt to run without dimming the lights to the best of my knowledge. BTW the gain on my amp is set less than 1/2 way. This may not make much of a difference but I'll provide you guys with all the info on what I've done, so I've also swapped out all the interior incandescent bulbs to LEDs. Right now I have a brand new 1.5 farad cap on standby from being installed (bought it cause it was only 30 bucks). I haven't put it in yet because I've been researching all the debate about them and I can't decide whether to put it in yet but I figured I would try everything else before hand in case the cap ends up adding to the problem for some odd reason.

In the end, the dimming is an issue for me because it's a new car and I'm getting HID lights installed very soon and I'd hate for a drop in current to make them malfunction. Then on the other hand, I have a theory that the HID lights might help the electrical system since they draw less power once they've initially been ignited.

Any Help would be awesome! Let me know if I can provide any more information. -Simon

Replies:

Posted By: haemphyst
Date Posted: August 13, 2007 at 4:01 PM

No matter WHERE the gain is set, of your input signal is telling it to make 425 watts, that's how much power the amp is going to make.

425 watts at 14v is STILL over 30A, and if your alternator is only (guessed at, sure...) 65A, then you are already using 50% of the alternators total capacity JUST FOR THE AMPLIFIER. If you have a 50watt amplifier in your car, but your car is already using 100% of the alternator, you need a bigger alternator, it's as simple as that. Now, if your car is using 80% of the stock alternator, (65A*.8=52A) that only leave 17A to run your amplifier.

Knowing that, what's your answer? Does 30 pounds of crap fit into a 17 pound sack? LOL You need a bigger alternator.

Also, as a last minute, tiny, little-bitty jab... cliche is probably not the word you are looking for... posted_image

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: lilkwazy2
Date Posted: August 13, 2007 at 7:59 PM

I asked for help, I didn't ask for a show of your arrogance so go belittle someone else if you must cause your power trip ain't helping and I don't need to read about it.

Posted By: haemphyst
Date Posted: August 13, 2007 at 8:50 PM

Dude, calm down... I did help you, I simply added a bit of humor. Your alternator isn't big enough, plain and simple.

...and if you're commenting about the last line, re-read it, I was completely joking, so indicated by the little winking smiley.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: KarTuneMan
Date Posted: August 13, 2007 at 10:26 PM

The problem cannot be defined as cliche..... but the question about the problem can be. posted_image

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Posted By: KarTuneMan
Date Posted: August 13, 2007 at 10:27 PM

This is cliche.....but true. "It takes power to make power"

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Posted By: csnut18
Date Posted: August 15, 2007 at 12:43 AM

First of all your stock Alt is more than 65 amps. It is at least 90 or possibly more. The toyota yaris has a 90 amp alternator so you don't have less than that. My acura rsx type s has a stock 110 amp alt. The subaru wrx has a 90 amp alt. I know the gm sedans like the pontiac g6 have 102 amp alts.

Posted By: KarTuneMan
Date Posted: August 15, 2007 at 8:25 AM

I found something! Not that it REALLY matters, just F.Y.I.

https://www.wheels.ca/newVehicles/profile/28534

Cold Cranking Amps @ 0 F (Primary)	- TBD - (with conditions)
Maximum Alternator Capacity (amps)	90 (with conditions)

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Posted By: csnut18
Date Posted: August 15, 2007 at 12:48 PM

hehe, I was right