Do these capacitors I see advertised everywhere really make that big of a difference? If so, is bigger better, or should I just stick with whatever size fits my amps. For example, I'm running a Sony 35x4 that's bridged to 70x2, and a Fosgate 40x2 (probably closer to 80x2). From all the info I've seen I should need a .5 Farad capacitor. Does it make sense to go with something larger like a 1.0-1.5 Farad capacitor?

 

Don't know if it makes any difference, but the speakers are 6.5" components for the front driven off the Sony, and Kicker 6.5" competition subs in the rear driven off the Fosgate.

 

I have 2 phoenix Gold capacitors that I am trying to get rid of for DIRT CHEAP. One is a 1.2 farad and the other is a .5 farad. Let me know if your interested.

 

What makes you think you need a capacitor? That's the question you need to answer. If the answer is "because they're there", you have too much money. If your lights are dimming when the bass hits, you may need a capacitor or better alternator. If the lights never dim, you don't need one.

I don't really think a 300 total-watt system would need a cap. There are many threads about this at caraudioforum.com, if you want to read more about it.

 

I wish I had too much money. :crazy: The lights dim when the bass hits, and I figured as cheap as they are running it certainly couldn't hurt. The alternator could need be getting "tired" considering the car is a 92. Thanks for the hint on caradioforum.com, I'll check it out there.

 

I don't have any capacitors in my system, and nothing dims with AC on, lights, & volume cranked.
(2) amps, 475 & 600 Phoenix Gold

 

Hmm, unfortunately that doesn't help a whole lot since you have a C5 and I've got a C4. I know I had the same problems with these amps in my 95 LT1 Firebird, so I'm thinking the alternators on the LT1s are just weak to begin with. I might go ahead and try getting it rebuilt just to see if it makes any difference before buying a capacitor, but then again if I can find a cheap .5 farad capacitor it probably won't hurt any.

 

I'm currently running 2 rockford 800 watt amps in my 96 Impala ss and yes the light dim alot when the Bass hits, I have added a 1.0 capacitor and the problem still there but not as sirius, if you add a cap to your system make it a 1.0 farrat, since you are going to expnd the money, this will help with your problem,but if you really whant to get rid of it, go the expensive way and add another batery to your system, it will run you about $400.00 including install, in my case I don't have another chiose but to add the batery

:mad

 

Check your voltage electronic gauge. I would guess those amps require alot of power and eventulally it will kill you alt. You could also get more power out of your amps with a cap.

 

A little information on caps: Every amplifier has storage caps in them for transient peaks in music... a 4db change in input level can mean a 200% change in output power. Now, if the power supply is starved for current (which car audio amplifiers are current based), instead of faithfully reproducing the transient, the amp will clip. We have all seen the external caps upwards of 2 farrads... quite large indeed! In order to place them inside an amp, it would take up half again as much room! Now, as for the myth of inserting caps to allievate dimming lights, etc... it may help a little, but the larger reason to add a stiffining cap is to keep the amp fed. Actually, if the lights are dimming, there are other problems! Either you battery is weak (which for all intents and purposes is a huge capicator) or the car's wiring is lacking. In either case, you are overloading your electrical system. I hope this helps a little.

 

Question for ya real quick. What size power wire are u running? 2,3,8,12? If the power wire is not thick enough, that may also cause dimming in the lights, especially with larger amps. Lots of times I see people with big amps, but aren't willing to spend it on wiring, which is just as important and end up having to redo their systems because of clipping and dimming. The alternator (as long as it's not worn out) should supply way more enough power for those amps of yours.

 

Why do you say that he can get more power out of his amps with a cap? Please don't spread wrong information. There is no magic that happens from a cap that makes an amp "get bigger". A cap is an energy storage device. That's all.

An amplifier works by boosting, aka "amplifying" an audio signal to a higher voltage which drives the speakers. It does this by converting the 12v (or 14.1v) DC from the car into a higher-voltage AC signal as determined by the source audio. The components inside the amp are designed to increase the input voltage by some multiple to make the output voltage.

An example might help. Say you have a 1V line-level input (mono), and you have a 100 watt amplifier driving a 4-ohm speaker. Since power (in watts) equals voltage squared divided by resistance, 100=v*v/r = v*v/4, v=20. The amplifier puts out 20 volts max, which is a 20-times amplification. Adding a cap can't make that any more. The phyiscal components inside the amp are only capable of multiplying the signal that much.

However, if the amp can't get enough current to drive it's 4-ohm load at the 100 watt level, clipping will occur. That means the amp starts to send that much power to the load, but the power is not available, so the power (which, in this case, is sound) decreases. By having a large capacitor near the amp, the amp is able to have enough power to maintain it's large output power. The capacitor can store lots of energy, but only for short times, which is why they help for bass: bass hits are usually large power but short duration. During the time the bass is "off", the capacitor is charging again. Another way to keep the amp happy with lots of power is to have large power wires from the amp to the power source (battery/alternator). Small wires can only handle a finite amount of current before they heat up too much and melt the insulation, and that's bad.

A battery and a capacitor are very similar: they both store electricity. A battery is slow to charge and slow to release energy, while a capacitor does both quickly. Another battery is another source of energy release, so the amp stays happy because it will have more energy available.

I hope this clears up some of the myths about these things.

 

Hey Non-stop u seem pretty knowlegable about this stuff. If he were to say upgrade the stock battery to a yellow top Optima, would it minimize the dimming since the Optima is a better battery? Any experience with that?

 

I don't have any experience with that. I haven't done much with car batteries, but I understand that Optima's are believed to be better. How are they better? If they can store more charge, or store it for a longer time, that's good, but doesn't really help this situation. If they can release charge faster, then it may help.

I believe that lights dimming when the bass hits is due to the inability of the electrical system (alternator & battery) to provide a constant voltage level during periods of large current draw. Let's say that your lights draw 20 amps, your ignition system draws 20 amps, and your stereo draws 10 amps when there's no bass, and 80 amps when the bass hits. That's 50 amps when no bass, and 120 during the bass hit. If your alternator is getting old and can only supply 75 amps max, and the battery can supply 40 amps instantaneously, then something isn't getting enough current, and it may be visible/audible.

I don't think regular batteries can supply that much current instantaneously, though. They're designed for starting the car and smoothing out some drops. Capacitors are better for instantaneous drops, but like we said before, if the rest of the electrical system can't keep up, a cap won't help much.

 

The simple rule about caps (as far as car audio is concerned) is for every 1000 watts peak output, mate a 1 farad cap. So 500W peak, a .5 farad would help, but anything less than that isn't a big deal.

 

Caps are as has been said energy storage devices. If you use good wire and have a battery that isn't bad you should be fine with most systems. If you find you need more power due to large amounts of bass being produced, add a cap. Lights dimming are symptomatic of the car's system not being able to produce enough power for the car to run on. Since bass comes in waves and not one constant noise, it will pulse as it taxes the system. I doubt you will notice in a corvette any difference in the system if you are below 500w. Over 500w you may notice this phenomina more and need a cap.
First things first.
Make sure you have enough power. Get an amp that is rated properly for your system.
Make sure you are running big enough wire. 8 gauge is big enough for a single amp of 300w or less. 4 gauge should be good to close to 1000w. After that you need larger wire like 2 or 1 gauge.
Make sure you have a good battery. The battery doesn't power the system. It starts the car. It also smooths the power output from the alternator. If you have a bad battery you will have problems starting. Upgrading to optima will help you if you have fume problems and you want to mount it inside the cabin. Under the hood it should make no difference.
If you have good amps, good wire, good battery and your lights are dimming you can solve this in two fashions: add a cap or add a backup battery. The cap should make sure your amps aren't starved for power. It will store up unused power and provide it to the system rapidly when needed during a thump. It is small and relatively cheap. Caps are all made by two manufacturers who inturn supply the names like Phoenix gold and Stinger and then they mark them up and put on their own labels and meters, etc. They are all basicially the same. The second solution is a backup battery. The battery will do basically the same thing the cap will but you can also put a one way voltage flow device on the wires going to it so you can have it powered by the alternator but it will run the sterio seperately from the other parts of the car and you can run it without running the car and not kill the battery that starts the car. This is called isolating the system. If you do this you want a marine deep cycle battery. You could run a 1000w car sterio all day on one and not have a problem. They are designed to provide steady power for long periods of time, not a quick spike like is needed for a starter.
If you have voltage problems you'll know it. You will see the lights dimming and the bass will be crapper than if you aren't running the lights and ac. If this is the case, get a cap. If not, don't waste your time and $$$.

 

Wow, never expected this much response. Ok, after doing some research and listening to opinions here, it sounds like I'm just going to rewire everything first with good quality wire and then maybe have the alternator rebuilt/replace the battery if I'm still having problems.

 

Your lights dim on loud passages of audio because the point in the wiring that you chose to get power for your amplifier shares a conductor that also supplies power to your lights. The large pulses of amp current causes a small voltage drop in that common wire and wiggles the voltage on the lamps. If you will run large wires directly from the battery terminals (ALWAYS put a fuse on the positive battery post to your load), then your lights will not blink and your amplifier will deliver more peak audio power before clipping and you will not need a capacitor. I doubt you need a new battery or an alternator rebuild. Try the direct to the battery wiring first. Large capacitors will help only on short audio peaks, but if you have a sustained tone (like an organ pedal note held down), a capacitor will not help . Besides, why in the world would you want to exceed the threshold of pain with such loud audio and damage your hearing?

 

Yeah, the battery and alternator are probably fine unless you are exceeding 1000watts or so continuous. Most people don't do this. Big wire should do the trick. If you haven't wired directly to the battery(and not the distriblution block next to it) then go directly to it. As jfb said, don't forget a fuse at the battery before you run the wire down the car. It is a safety issue for you, not your amp. If there is an accident and the wire is breached, it can cause a fire or your battery to explode. Not good in a corvette.;)
p.s. I'm running about 680 watts of power that would be about on the same scale as you rated your 40x2 fosgate with 4 gauge power wire and no dimming whatsoever. My power output is roughly 5 times yours. What? What? Did you say something jfb? :cheers:


[Modified by 92TripleBlack, 9:29 AM 1/26/2002]

 

I SAID," WHY WOULD YOU WANT TO RUN SUCH HIGH POWER AUDIO THAT IT WOULD RUIN YOUR HEARING". NEVER MIND. I SAID NEVER MIND.