I just finish installing my audio and decided to crank it up and check to see if any lights dime. It was at night time and I had my headlights and interior lights on and the car at idle speed. I didn't really want to put any excessive load on the alternator from different loads accept the lights I was trying to keep it more realistic. I'm pushing a RF 400a4 4ch amp into a sealed box with 10" RF. I have two chs bridged into one for the sub, and the other two feeding the front speakers. This set-up is giving me the sound I was looking for, more low bass. But there's something missing, the bass seems to be outpower the mids and highs. So I'll probably get another 2ch RF amp to power the sub and use my current amp to power the 4 speakers and new tweets because it has a built in x-over with lo, full and hi pass with different mhz setting and independent front and rear gains. So after I install my second amp and there's still no dimming, I should be ok? Or is a cap a insurance I should invest in.

 

You need to check the charging system with a multimeter. That is the only way to know what's going on with the power.

 

what do you mean charging system? lastnight i checked the voltage of my battery while my sub was blasting and the lights were slightly dimming, and the lowest it dipped was like 11.75 or somehting.

 

I had did that exact thing, I place my DVOM on the battery terminals and crank the volume up, 14.08V was the lowest. So I turn off the audio and it went to 14.27V both reading were check at idle speed. What I'll probably do next after the car fixed is place a amp meter acorss the neg battery cable and with key-on, engine-off crank up the volume and really see how much amps the audio pulling, of course just long enough to get my readings.

 

acceptable reading? And should you do this with car on,lights, and audio blasting?


PJ

 

you guys seem very knowledgeable about this subject matter so i have a question. i hae an 89 max and i just ordered a prfile 4 channel amp. i plan on running 2 channels to the 2 12" subs i just bought, and the other 2 channels to the rear speakers. then i am gonna take teh factory amp and put it to the front speakers. my amp is 75x4 rms. how do i find out if i need a cap or what the reserve capacity is of my alternator?
also, does anyone know where to get the specs on the factory amp (its a clarion) ?

 

i wouldnt thinkyou would need a cap for that much power. I used to run a 600 watt jbl amp on 2 15's and it didnt need a cap. I even had a second amp for mids and highs and had no problem powering the system. I used an Exide Nascar Select battery and had no real problems with lights dimming. At night with subs on full you could just barely see the headlights dimming but not enough to notice while you were driving. It was also very loud, 154.6 db and a cracked windshield!

 

IMHO a cap is always a good idea in any audio setup. Now some people can't justify the cost when they see no problem, i.e. the lights aren't dimming. Depending on what size of system you are running or planning on running, there are different sizes of caps. They range from 1/4F, Farad, all the way up to 1F and larger, or if you want real over-kill you can but the Pheonix Gold C.A.P. which is 15F. Way more than anyone in any lifetime would need. Okay, from what I have seen on different Audio boards and the like is that it won't hurt, it can only help. So to sum up, if you don't want to spend the money and you don't notice any problems, don't buy the cap. However if you feel that you want to upgrade your system soon, or just want to add a cool thing to your audio setup, for the "uhh-ahh" effect. Drop a cap in. Okay, I've rambled enough and remember, this is just my 2 cents!!

 

I think getting a cap is better than not getting it. Like the saying goes, "it's better to be safe than sorry." And I learn the hard way, the "sorry" way. So, I'll be getting a cap; probably a 1 farad cap is good enough for me.

 

My headunit powers my speakers and the damn display lights dim when I crank it up. Maybe I could hook up a cap to the headunit. Now that would get the "wtf is wrong with you" effect! Anyways, this post had no point so just ignore it.

 

Dude, when I cracked up my system the first time, my lights did not dim either so I didnt buy a cap....I went into a discussion on an audio board and all these guys were recommending a cap anyway, they said you would notice the different when play really deep lows, so I bought .5 Farad Rockford cap and it did make a difference, real lows got even clearer and my friends noticed it too, that thought I got a different system and I feel more comfortable when I am hanging out at he car wash or the car line and just jamming my system hanging out with my homies, my car cranks right up even after a couple of hours of playing the stereo full blast...I think a cap will really help your battery last longer, a great benefit to me...

 

I think I will be in the market for a CAP, just not in a big rush. Since I finish installing my audio I have the urge for a bigger system.
1) I realize that a capacitor stores energy, I'm assuming it stored DC energy, how much energy(DC) does a CAP stores? or does it depend on the Farad size?
2) What are the typical energy storage in a CAP, besides 1/4, 1/2, 1-Farad etc?
3) When you're listening to your system while washing your car with ign off and acc on, will the system drain the storage energy from the CAP first before taking from the battery?

 

try running a bigger wire to your head unit

 

The specifics of a capacitor escape me, even though I have a BS in electrical engineering. I don't know the particulars on the energy storing capacity, but I could figure it out. To answer your questions as best I can: Yes a cap stored DC energy and yes it depends on the size. The size of caps, the ones used in audio, are usually 1/4F, 1/2F, 1F, and 1-1/2F. Then to get more you can buy 2 1F caps and hook them in parallel and get 2F.

In more general terms, a capacitor acts as a small storage container for current. When your system is trying to play those really low bass tones or is at high volumes, the amps begin to draw more current from the alternator and battery. The cap sits between the battery and the amps and when the amps try to draw more current, the current that is stored in the cap is drawn instead. Then the cap restores it's supply and waits for the next big bass hit or whatever.