# Cap



## Xxboarderxx (Nov 11, 2004)

Anybody suggest and capacitor for reference. I am getting a toss up on either a digital cap from audiobahn or a digital cap from rockford fosgate. ANyone have either or?


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## asleepz (Feb 24, 2004)

Audiobahn looks better. Other than that they are the same


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## Xxboarderxx (Nov 11, 2004)

alright cool thanks that audiobahn is just a plain silver i think it looks bad too. Peace


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## Azgrower (Oct 1, 2004)

Why do you need a cap? I say spend the money on updating your Big 3 under the hood.


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## Zac (Mar 10, 2004)

Azgrower said:


> Why do you need a cap? I say spend the money on updating your Big 3 under the hood.


werd. caps suck, their just bandaids. for the price of a decent cap, you can get an Optima Yellow Top.


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## Punkrocka436 (Jul 8, 2003)

you dont need a cap

you need to invest about 20 dollars in 2 gauge wiring and upgrade your big three. If that doesnt solve your problem, you need to get a deep cycle battery like an optima yellow or blue top, if that doesnt solve your problem you need a higher output alternator

Caps are a waste of money, and will put an even bigger strain on your electrical system


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## sr20dem0n (Mar 19, 2003)

good read:

http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi?ubb=get_topic;f=1;t=022965;p=1


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## captain_shrapnel (Sep 10, 2004)

I agree, no cap. Amplifier manufacturer's know how to construct the power supplies for their products. If you think you need a cap, you have other problems. Yellow top + big 3 = :thumbup:


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## Nismo1997 (Dec 26, 2003)

I have 2 gauge wire and ground red top, and when my bass hits. My lights still dim. I just got a 2.4 far. cap for 88$ 


Ill keep you posted on how it works after the cap.


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## Azgrower (Oct 1, 2004)

Nismo1997 said:


> I have 2 gauge wire and ground red top, and when my bass hits. My lights still dim. I just got a 2.4 far. cap for 88$
> 
> 
> Ill keep you posted on how it works after the cap.


In that case I would still get an electrical upgrade under the hood....a new or rewound alt....Caps are a waste o' cashola


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## Punkrocka436 (Jul 8, 2003)

okay, the cap will solve your dimming problem. Caps can discharge in a tenth of a second, but they take up to 20 times that time to recharge. While the cap is recharging, your putting an even bigger strain on your electrical system. When you see dimming lights, you have to act. Putting a cap in your system is like putting a bandaid on a bullet wound. Its not a good idea.

Let us know how long it takes you to fry your alternator. B14 alternators arent exactly known for their excellent build quality. 

I had dimming issues with no big three, the problem is gone now that i did my big three. Hell, I only used 4 gauge wiring. I bet that if you were to upgrade the wiring to 1/0, you wouldnt have any dimming at all.


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## xbrandonx (Mar 27, 2004)

there is not a fuse in the ground wire to begain with is it really necessary to put a fuse in it?


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## captain_shrapnel (Sep 10, 2004)

no, never fuse a ground wire.


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## Matt93SE (Sep 17, 2003)

please explain why you would want to fuse a ground wire..

To help you come to the conclusion, tell me what would happen if you touched it to the frame of the car. alternator case? engine block?

now explain what would happen if you touched the +12V side of the battery to any of those points.


As for the cap issue, I'll save you a lot of reading.. the old-school electrolytic caps can and do help stabilize the voltage for SHORT transients and the occasional burp, but that's IT. The best thing to do is properly build the battery, alternator, and wiring to handle the power. you can't squeeze blood from a turnip. You're arguing with the laws of physics if you think you can run a 10kW system on a Honda alternator and get away with it for more than a few minutes and not hurt the battery. I'll give you a hint.. physics will win.
The new skool 25,40,50,100F carbon capacitors are CRAP. absolute CRAP. they have huge ESR and only hurt the system. sure they store lots of energy, but your car battery stores hundreds of times MORE and has lower internal resistance anyway.


All that said, I have an old school 2F cap on my system and it'll stay there forever.


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## Punkrocka436 (Jul 8, 2003)

^wow, two things we agree on


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## Matt93SE (Sep 17, 2003)

I'm an electrical engineer.. I obey the laws of physics. The stuff we argued in the past is opinion. All of the above is concrete info that nobody in their right mind can deny.

I learned a lot of it the hard way.. on a test bench in the lab...

I've built several audio amps and CAN vouch for using quality capacitors in the circuit.. 
(part of my "a watt isn't just a watt!" arguement... I have two amps that I built a while back.. both are 400W mono amps. one I built with the cheapest electrolytics I can find, the other, I built with high quality, low ESR electrolytics and mylar/poly caps where I could get away with it. the cost between the two amps wasn't all that much- About $40 difference betwen each when I spent $500 in parts on the whole project.

The amp I built with the cheap electrolytics still puts out nearly the same power (about 25w less on the crappy amp, but that could be from the variations in the output transistors).. Anyway, distortion is INSANE on it. You can barely tell it's the same music I'm playing through the good amp. The amp I built with good components actually sounds pretty good. I now wish I hadn't wasted that $150 on the circuit board and mountain of output transistors on the crappy amp.

But I still proved my point on the cap theory...


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## Punkrocka436 (Jul 8, 2003)

I just did a project in physics about the uselessness of caps in car audio, and there is STILL some guy who swears I am an idiot because i dont use a cap, and that if i talk to any "real installers like the guys at best buy and circuit city" (at this point i laughed and walked away) and they would tell me that a cap is essential.


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## Matt93SE (Sep 17, 2003)

Honestly, they DO make a difference. but only if you're using the old school electrolytics, and only for short periods of time.

I'm running a 2500W RMS system (and it's not a bogus number either.. PPI art series put out MINIMUM of what they're rated at... usually about 10% above.)..

their power supplies are HIGHLY regulated, which is one of the main factors in the system not caring about the power supply going in. the only difference a cap will make here is not blowing up the alternator's rectifier and voltage regulator on high power transients.

the unregulated amps may benefit more from a huge cap or a bank of caps, but the ones like PPI don't make a difference on the sound quality. (hell, they make the same power at 9V as they do at 15V!)


It's all in the design. what many of these fools don't realise is that there's a huge bank of tiny caps on the amp's circuit board itself. they take care of the amp for the most part, and the problems they're seeing on the rest of the car's electrical system are confined to it.


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## sr20dem0n (Mar 19, 2003)

xbrandonx said:


> there is not a fuse in the ground wire to begain with is it really necessary to put a fuse in it?



Definitely do NOT fuse the ground wire, that's an accident waiting to happen.

#1 it won't protect anything, so it's pretty much useless
#2 if it happens to stop conducting due to a defect, your amp now has to find its ground elsewhere. If the ground circuit is completely isolated from everything else in the amp, then it will simply turn off and you're lucky. If it's not, there's a chance that it will try to grab its ground from the rcas running to the headunit. Well, if that happens you can say goodbye to the preouts on your headunit. Hopefully a quality amp won't have this problem, but it all depends on how it was designed and constructed.


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## xbrandonx (Mar 27, 2004)

sr20dem0n said:


> Definitely do NOT fuse the ground wire, that's an accident waiting to happen.


I thought I read that somewhere in this post...looking back I didn't..hmmm I was thinking that was pretty stupid to do.


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## Matt93SE (Sep 17, 2003)

That's a misnomer, assuming the amp is properly designed (and 99.9% of them on the market are.)

generally, the RCA ground has a 10-100 ohm resistor in series before the chassis ground of the amp- so the amplifier can't sink current through the RCA line-- never more than 1.2A anyway. 
(12v/10 ohm = 1.2 A)

I've had a ground cable come loose before. the amp does some weird stuff, but in essence, the clipping light comes on to show a fault and the amp stops working. can't do much more damage than that.. again, that's in a properly designed amp.. Anything from a major manufacturer will be that way. a thump or crunch or Boss amp may be a different story, and I don't consider that stuff properly designed.


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## Zac (Mar 10, 2004)

Matt93SE said:


> a thump or crunch or Boss amp may be a different story, and I don't consider that stuff properly designed.


who does?


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## calgearhead (Sep 28, 2004)

Ok I don't know squat about electronics but I do know my Alpine 9831 with stock speakers (for now) and Memphis 1100W amp and Pioneer Premier 12" sub sound great. When I'm idleing my lights dim. Thats the only time they do. However I am curious about upgrading the "Big Three". What are they??? I have the stock battery in for now and will soon replace it with the Red Top Optima thats in another car. Or, should I just spend more $$$ and get a Yellow Top and let the Red sit some more??? Any help would be greatly appreciated. :cheers:


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## Punkrocka436 (Jul 8, 2003)

You should hear a pair of koda components if you think stock speakers yield good SQ


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