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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through November 17, 2003 » Amplifier Stiffening Capacitor « Previous Next »
By Levi Cress (levi) on Thursday, September 04, 2003 - 9:26 pm:    Edit Post Delete Post

The lights on my truck are really starting to dim w/ the bass in my system. I figure the easiest thing is to add a cap, but there is quite a difference in price on these. On I can pick up a 1 farrad for $60 bucks but I don't know jack about this stuff. Is it worth spending more on a "nicer" one or is it basically just get the cheapest one I can find? Also, what about the ones w/ the digital readout things? Oh, and I'm running a PPI 2 channel bridged for 360 watts to a JL W3 12" (i think its a W3 in the stealth box) if that matters.


Levi Cress
Palo Alto, CA

By John (hyperryd) on Thursday, September 04, 2003 - 11:47 pm:    Edit Post Delete Post
One ferrad should be fine for that amp. Just get a decent quality cap and you should be good. I have tried some cheap ones and two of them have leaked, so spend a little extra. Make sure you mount it as close to your amp as possible and you will be good to go.
By Sean M (magic) on Friday, September 05, 2003 - 7:53 am:    Edit Post Delete Post

You might want to try larger gauge wires between the battery, amp and ground first.

The cap is just an other device for the charging system to power. It might clean up your bass a little bit, but I really doubt it will help the dimming lights.

You are not running that big of amp, how is you charging system? Alt, battery... all they all in good shape?

If you pick up a cap, get one with the fast discharge and recharge rate you can find. Some of these caps are slower than what the amp is drawing from them. So they sit there partially charged in between bass notes during loud play.

By Levi Cress (levi) on Friday, September 05, 2003 - 8:47 am:    Edit Post Delete Post
Thanks for the advice guys....

Sean, that's a good question.... What's weird is that it seems to be getting worse w/ the dimming..I didn't notice it nearly as much a couple years ago when I did the system...and it's getting worse now. I've ran my battery dead a couple times at the drive-in movies (oops!) and I've heard that you're battery isn't as good after you've done that? Is that true? Maybe I need a new battery...and maybe my alternator is giving up on me? I'm running 2 PPI amps. The 2 channel (2360) and another 4 channel (4240)...both are relatively small though....

What gauge would be the minimum I should run? I liked the cap idea just because it seemed like a really easy fix..but the wires wouldn't be too bad either since I could pull the new one through w/ the old wires...also, should I run the ground straight to the battery, or is it fine to just ground out to the truck someplace?

Thanks guys!!

By Stewart McLean (gizel) on Friday, September 05, 2003 - 9:59 am:    Edit Post Delete Post
Levi, if you have run your battery dead more than once then you should replace it. Everytime you run it dead you lose the electrolytes in the acid that gives the battery a charge. I would be willing to bet that a new battery will fix your problem. Also if it is the factory battery you should think about getting something with a little more cold cranking and Amps, this way you will not be as likley to run it dead.
By tuneman (tuneman) on Friday, September 05, 2003 - 3:30 pm:    Edit Post Delete Post
A cap probably won't fix your problem. Get a higher current battery. If you still have problems, use 8 guage wire to each amp, or one 4 guage wire. Your grounds need to be on clean, bare metal and as close to the amp as possible. Don't run a ground back to the battery. If you still have problems, check your alternator rating and replace it with a higher output one if necessary.

Your PPI amps are internally regulated(unless they're the cheaper series), so the cap won't help much.

By Rod McInnis (rodmcinnis) on Monday, September 08, 2003 - 4:30 pm:    Edit Post Delete Post
A capacitor of any reasonable size is not going to have enough storage to have any significant difference beyond an instant. If you are seeing the lights dim, you are experiencing an excessive current draw that lasts seconds or longer.

If the problem is getting worse, then you are either drawing more current, generating less, have a weaker battery, or the connections are going bad.

It is possible that your speakers are getting worn out and the amp is working harder to get you the same sound you were accustomed to. I suppose that it is also possible that your hearing is going bad and you are turning the volume up higher than you used to in order to compensate..... :-)

It is possible that the alternator is not providing the same output that it used to. It is possible to blow one of the diodes in the alternator and have its output drop considerably.

If the battery has become weak then it would not be able to respond to the high current demands. Is the battery dedicated to the stereo system? For either the alternator or battery explanation, I would expect you would have trouble starting the truck.

Corrosion on the electrical contacts can certainly cause the problems that you describe. Fuses that used to make good clean contact with the holder can become lossy. The contacts on the battery post are notorious for going bad (although, again, I would expect you to have trouble starting the engine).

I would suggest using a voltmeter and take a look at what is going on. Measure the voltage at the battery when the lights dim: does the battery voltage (measured right on the battery)sag or stay constant?

If the voltage sags from 13.5 volts down to 12.something, then I would suspect the voltage regulator/alternator.

If it sags below 12 volts, then I would suspect the battery as having problems.

If the voltage stays relatively constant, then I would suspect the wiring. Since the lights are dimming then I would suspect the wiring that the two share, which should be the connection from the battery to the fuse block.

By Levi Cress (levi) on Thursday, September 11, 2003 - 3:53 pm:    Edit Post Delete Post
Thanks for all the advice guys...I went in and had the battery checked and that seemed to be the culprit. I put in a new battery and all is good so far.........

Can't say how nice it is to have people that know their stuff so easily accessible! Thanks again!

Levi Cress
Palo Alto, CA

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