Hey all... I have a Sony 1200w amp and 2 12" Infinity References. I also have an Optima Red Top battery, but I noticed that when I turn the volume up almost all the way, the lights dim slightly, so I decided to try a capacitor. After installing a 1.5 farad, I didn't really notice any difference in sound, and the lights still dimmed a little when the volulme was up loud. The capacitor turns on and everything and the voltmeter on it functions correctly (changes voltages), and the subs are functional. Here is my rough sketch of how I installed it:



Hopefully you guys can follow that. Basically what I did was attach the positive from the battery to the capacitor, and then the positive going out to the amp to the same place. I did the same thing for the ground, running it from the chassis to the negative terminal on the capacitor, then from the negative terminal of the capacitor to the amp.

Anybody have any insight? Thank you!
Shawn

 

What gauge of power and ground wire did you use? And are you using a sufficient grounding point (raw metal)? Did you upgrade the ground at the battery?

 

im using 4 gauge wires all around, and the grounding point is on bare metal, so i THINK it's working fine. the amp works and everything though, so could the ground still be the problem? what do you mean by upgrading the ground at the battery?

should i get separate grounding points for the capacitor and amp?

also, is there supposed to be a noticeable difference in the sound quality of the bass?

 

I'll try to explain it, although I'm not the best at getting my point across.....4ga all the way around is good for starters. No real need to separate the grounds at the cap and amp in the back. Using a ground distribution block would do the same thing, so you're fine. Your car, from the factory, probably came with 6ga wire on the B+ and ground side of the battery running to the rest of the car. That gauge of wire was sufficient to run all of the accessories at the time the car was stock. Keep adding more accessories to it (neon, audio, etc.) and the current requirement is greater. Now that 6ga wire isn't sufficient enough to handle that capacity. So with an audio system, the dealer will sell you into an amp kit or a spool of wire to run back to the amp. With an amp kit, you receive a large amount of B+ wire and a small chunk of ground wire to go from amp to grounding point. They say the shorter the ground wire the better, that's correct. But up under the hood, you increase the size of the B+ wire, but not the ground wire from the battery to the body of the car, why? Direct current only flows one way, but you need and equal amount of copper on both sides of the battery for the current to flow properly. Go aquire a small run of 4ga ground wire and some ring terminals then add that to the negative side of the battery and to the body.

As far as a noticable difference in the bass...in some cases, yes. If anything the amplifier will notice the difference. The efficiency will be way up and the amp will run cooler. So you may notice a difference in sound. Sounds like you have the right amount of capacitance to match the power of the amplifier, just upgrade the ground and see what that does. If you have enough 4ga and enough ring terminals, you could even run an additional ground to the engine. From what I understand the factory grounds on the engine are really poor.

 

Aside from whats posted above...I have to ask did you charge the cap prior to installing it> Dont take offense to this question as its not intended that way, but sometimes its the simpliest things....

--Don

 

i did charge the capacitor when i originally installed it.

i added a 4 gauge wire from the negative terminal of the battery to the chassis, but there is still a slight dimming of the lights (very slight though) whenever the volume is turned up. could there be any other problems, or is my capacitor working correctly?

when i first turn the car on, the voltmeter gives me around a 14V rating, but as i turn the volume up higher, it gets lower and lower until it gets to about a steady 11.8 or 11.9 (when the volume is all the way up). should the voltage be going that low, or should it be staying up at the 14's? my lights didnt dim that much to begin with, so is there a way to tell that the capacitor is actually working the way it is supposed to?

 

Hyperground....

Solved my light dimming problems anyway...

drew

 

HOLD UP, im suppose to ground the amp on the cap??????????

 

hyperground??

 

Hyperground is the grounding kit for the engine compartment if I'm not mistaken. You must be pullng some serious current to get the voltage to fluctuate that much. As long as it's not holding at 11.8-11.9. One trick learned at the Mobile Dynamics school is that amplifier gain setup may be the next option. Don't know if you've already done that. This is where you match the output voltage of the source unit (RCA output voltage) to the input gains on the amp. To do it right, you'l need an oscilloscope. There's other ways of going about it too. If you can track down a test CD (like Autosound 2000) that has a straight sine wave or plays a single frequency with 0dB gain or maybe a slight gain, this would help. If your gains are up too high, this causes the amp to clip at the output section. When the amp clips it trys to put out more power beyond it's capabilities and draws excessive amounts of current in the process. Now by getting the input gains set correctly, this may not fix the headlight dimming 100%, but it will sure help. If one point in the vehicle draws too much current, that robs the current needed for the other accessories causing voltage drops here and there. I wish I could explain how the gain setup works with an oscilloscope, but I'm sure there's other threads on that subject.

 

OK. The problem is probobly the fact that it is wired up differently then i was ever told to wire up a capacitor. There are the 2 connections on the positive side. 1 that goes from the power source and the other that goes to the amp both connecting to the positive side. On the negative side you should only have 1 ground wire connecting to the chasis of your car. Not to your amp. Try and ground the 2, the cap and the amp, in 2 different spots. Try that.

 

don u dont need to charge the cap in order for it to work. by not using a resistor you cannot regulate the current that is charging the cap and instead of it charging over time, it charges in miliseconds pulling large amounts of current which could blow the fuse on the power wire. the cap would be fully charged either way. the latter method is dangerous though because the cap could easliy pull 400 amps from your battery.

 

not true. the output stage does clip the signal, but no more current is drawn from a clipped signal than from a signal that is on the verge of clipping. you are talking millivolts and miniscule impedences that equate to a small differential changes in current.

 

no that's not the problem. you can ground the amp to the cap and then ground the cap. there is no wrong doing there. the problem he is experiencing is a lack of current from a weak alternator, that's all there is to this besides upgrading ground wires. caps wont help unless you have a strong enough alternator for the application. caps are only benefitial when you have moreeee than enough current available. id say ditch the cap because you are only risking diode damage on ur alternator.

 

wow... really? ditch the capacitor? i tried connecting the amp and capacitor to 2 different ground points, and that didn't really help. and i also upgraded the ground from the negative side of the battery to the chassis, still with no better results. i think that you might be right about the alternator not being powerful enough, but wouldn't more maxima owners complain about this then? my system is not THAT big.. many people have bigger. how much does an upgraded alternator run? the capacitor's voltmeter is doing the same thing - going down to 14.9 or so. is my amp simply too big for my car or something? is it safe to have this big of an amp?

is there any other way to fix this problem? its not like i have that huge of a system.... this is my amp:

http://sm.crutchfield.com/S-61j3kIPP...fo&i=158XM2200

shawn

 

bump.......

 

i also am using a 200watt rms xplod amp with a cap

 

2DaMax: do you have any problems with your setup?

some additional info: i have noticed that even at very low volumes, my clock's and indiglo gauges' brightness correspond to the RPM's of the engine..... so when i am not pressing the gas, the gauges and clock are dimmer than when i AM pressing the gas pedal. the climate control display brightness stays the same though. there is obviously something else wrong, other than the capacitor. is my alternator too weak? do i need an auxiliary battery? should i get rid of the capacitor (this dimming of the clock/gauges was happening before the capacitor)?. i just want my sytem to work correctly, and i need help figuring out the part that is causing all my troubles. please help me out of my predicament!

shawn

 

Your problem is the alternator. Adding a 2nd battery will do nothing but add more of a load to the alternator than you have now which will make the problem worse. I suggest upgrading your alternator to a higher amperage unit to resolve the problem. I also suggest you upgrade your ground points for the alt and battery which will help matters as well (hyper ground will work here as well).

 

how do i upgrade the ground for the alternator? how much will a more powerful alternator run me? do alternators deteriorate in performance over time? if so, is there any way to get my current alternator to run like new?

shawn

 

I believe the stock alt was 110amp. You can take your alternator to an AutoZone and have them check it out to see if it is able to put out the rated amperage. If you need to upgrade, I would suggest finding out what the maximum amperage draw of the vehicle is (with headlights and A/C on full is preferred), add the maximum current draw of your amp(s) to that number, then get an aftermarket or rebuilt alty that can sustain that level.

 

turns out the problem was the alternator... it was only cranking out about 70 amps. i got a new 125 amp alternator installed, and everything seems to be working fine now. thanks for all the help!

 

No problem. Glad its working