I'm setting up my car audio stuff, basic speakers all around, but a sub and an amp to go with it. With the sub and amp and all, do I really need a capacitor? I mean, i've heard you can run without them, I plan on eventually getting one, but would it cause any harm to any equiptment to run without one until I get enough money to get one? Also, when I do get around to buying one, what should I get thats good for the money?

 

I must be slow or something but I don't know why you would need a capacitor? A capacitor is essentially two metallic plates that hold a charge. Caps are dirt cheap...

I don't think I understand why you would need one. A cap can be used as a DC block but you wouldn't need one. The amp has a DC block inside it. Please explain because I really think I'm missing something here.

 

hardly cheap

http://www.etronics.com/product.asp?...ore=&catid=309

 

Now caps at AC (freq) create impedance (in a sense resistance) knowing this the caps are used for filters (in Audio terms Crossovers). Not to regulate power so it's safe to run without them.

Here is what I mean:
Xc(impedance of a cap)= 1/JWC Where W= 2*pi*freq
Where pi= 3.14

Don't worry about the J components that's just to let you know that the current is lagging/leading.

Anyhow as you can see by the equation at DC (zero freq) the impedance is infinite therefore an open is created (DC block). Now at AC the impedance fluctuates because of the frequecies that are being heard. for this is why a cap is used as filters to create high impedance at some freqs (block) and low at others (passing signals).

But unless I'm still understanding wrong but I can't see why you would need a cap. So again it's safe to run without them.

 

What size amp are you running?

 

not sure yet

 

Whoa! now that's some fancy ****!!!

Ok we just had a discussion here at work. I think I know what they are for now. Surge protectors. At audio freqs (since it's almost DC) the capacitor has a longer charge time and threfore creates a protection of voltage (Caps charge exponentionally). But this is for people that are running an extreme amount of power I doubt that need one.

Just don't leave your stereo at full blast when you turn it off. So when you turn it back on the speakers don't get a "shock". Think about it, turning your stereo back on after you left it at full blast the surge of energy would create a shock effect on you speaker and most likely blow it. Kinda like jumping on freezing water rather than easing in. If this capacitor is hooked up and since a capacitor charges exponentinally the surge that the speaker would see would be also exponentionally and therefore prtect your speaker.

No you don't need one. It's over an overkill for an average stereo system.

 

You can use one. It will help your battery out! When you hit hard, ever notice your lights get dim? The battery can only do so much so quick.

Now, screw the "audiophile" stuff. .5 and up IS overkill. Just go to a science store and get you're self a .125-.25 PC grade cap. I've used em. They work great and those ARE cheap.

 

I would wait to see what kind of amp you are getting. I had a 2000 watt amp before and I didnt use one, but I needed one. If your under 800 you dont need one. It will make your amp run more effeciently and keep those really deep bass frequencies hitting hard. At the most just get a 1 farcad one.

But it all depends how weak or strong your electrical system is. I say wait and see if you'll need it. If you need one, they are super easy to install and can get it done in like 10 min.

 

I would wait to see what kind of amp you are getting. I had a 2000 watt amp before and I didnt use one, but I needed one. If your under 800 you dont need one. It will make your amp run more effeciently and keep those really deep bass frequencies hitting hard. At the most just get a 1 farcad one.

But it all depends how weak or strong your electrical system is. I say wait and see if you'll need it. If you need one, they are super easy to install and can get it done in like 10 min.

 

you really only need a cap when you push in excess of 1000 REAL WATTS. The general rule of thumb i believe is 1 farad for each 1000.

You see, a capacitor is sort of a buffer between your battery and amp. It stores electricity that can be drained instantly into the amp.

Batteryies can't drain instantly, this is why they go bad when you crank em too much. Depending on power (a 1500w boss amp won't puch 1000watts... well clean anyway at any reasonable ohm load), the cap can add a lot of spl to a sub system...

Most people don't need capacitors.. I've run 800 watts into 3 12s and not needed one.

Now, I'm running 1400watts into 4 10s and I'm using 2 farads... But now my lights don't dim and the bass is much louder...

Check out www.cmttrading.com they list for around $60 i believe. Remember that a cap is a cap. All are built the same way, probably by the same company. Don't buy a label.

 

I've got a Fosgate 100X2 amp. (I can't remember what it actually puts out) pushing 2 Eclipse 8101s bridged. There was a noticable difference when I threw in that 1/8 farad cap. If you have a question about it, just get one. Unless you have a competition setup, ot doesn't matter if it's pretty. Paint the thing if you want. Like I said, the PC grade ones are cheap (a little fatter though). So get one. If you don't like it....oh well.

I'm trying to figure out how only 600 more watts required a whopping 2 farads?!? Eh....to each their own.

 

Now this is a MAN'S capacitor:
http://www.rockfordfosgate.com/press...rcaps_ship.pdf


There are power supply capacitors inside the amps. So whether you need an extra "voltage-stiffening" cap varies from amp to amp.

The cabling between your battery and amp can factor in resistance-wise, as well. A higher resistance wire (ie: too small diameter) can somewhat isolate the amp from the battery, and starve the amp during large current transients. This may cause some distortion, which may not be audible, but may keep you headlights from pulsing. But a reasonably sized wire won't have any problems. A more realistic culprit is the battery's internal resistance, which plays a factor in the same way. It can vary from battery to battery as well.

-IG

 

I think you should run a capacitor. You'll have it already there if you decide to upgrade. And they're not expensive. If you hear your subwoofers make a popping sound, you definately need one. It will save you a lot of hassle in the long run. I had a stinger capacitor that worked fine.

 

The capacitor , when charged, will allow for the amp connected to it to run at a higher voltage, allowing it to have a higher output. The 5 farad cap in my cadillac allows the sub amp to run at about 14.7 volts, while the amp for the interiors runs at about 12.4. Not much of a difference, but hey, it works. The lights still dim, but hey, i'm running a 1700w system. Capacitors do not however take a load off of your alternator, so you will be running your alternator harder, as the capacitor charges off the alternator, and discharges, your alternator will bear the load.

 

thanks rjuge,

We were having a discussion here at work and couldn't figure out exactly why there was a need for one. Now it makes perfect sence. The cap helps as a surge protector in a sence that the amp uses the stored energy first so the lights don't go dim/blink.

Learn something new every day .

 

Whoa whoa whoa....the cap will only have whatever voltage it was supplied with. IE whatever the alternator's putting out. How can you have different voltages going to different things unless you have some regulator in place? If that's the case, then why? If you can have everything run 14V, then do it. The amp will handle it.

 

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