no shit... i'm only going to be running a single jl audio 500.5. our cars are not ford econoline vans,lol.

 

my amp is a mtx blue thunder pro 1502 1600 watts

when i do install it what will be the signs that i need a cap?

 

lights dimming, ect? for me, i had lights dimming and the rpm's would drop when the bass hit.

 

headlights, radio, and dash lights will dim when the bass hits. The power draw from the amp will take away power from the other accessories.

I have two 15" Diamond Audio subs and an 800watt Rockford Fosgate amp. I should use a cap if I ran it full bore all the time, but for the occasional showoff in a parking lot or driveway, there's no reason for one. My volts never drop below 13.5-13.8 when I'm running it loud. My subs/amp could lower it to 12.0 if my ears could handle it, but I never run it that loud.

 

alright sounds good

looks like ill have a lot on my hands this weekend with taking out the backseats so i can wire it cleanly. thanks everybody ill let you know about the results

 

First off, that's 40W, 10W per channel. Also, it depends on the ohm value of the speakers. Stock stereo speakers are usually 4 ohm. High quality speakers are usually 2 ohm. You get more bounce to the ounce out of high impedance speakers, but more quality out of lower impedance speakers. So, in my case that's a total of 100W because I have 5 speakers at 2 ohms.

a subwoofer requires alot more then 10W to make a sound. Average listening on a subwoofer will vary, however 100W is a safe number. The amplifier, depending on how efficient it is, will draw more to run itself and perform various lighting tasks. So anywhere from 100-150W. That's an automatc 200W for my stereo system at normal volume. with a full capability of 800WRMS (including both amplifiers)

A capacitor is NOT a band-aid. It levels the voltage between alternator pulses when you'd normally be pulling from the battery. Instead of highs and lows on every little alternator pulse, you get a flat more steady voltage.

A capacitor is a barrier between your system and your battery and will extend the life of a battery. A seccond battery is a band-aid and means you get twice the amount of time between replacing batteries. A capacitor is renewable and will not require replacement.

In this situation, it may only extend the life by a few minutes.

 

I wired mine cleanly without taking out the back seats. I ran it under the panels (door sill panel) and the backseat side panel.

It would be best for you to START by determining how you're going to run the power wire from the battery into the cabin... through the fender grommet or drilling the firewall.

 

^^ Same here! You can't see any wires, even in the hood and trunk. My entire terminal goes into a 1.5" wire loom.

 

Let's take a WAG and say your sub is rated at 88dB @ 1m/1W. Doubling the power yields a rough 3dB increase (barely noticeable)

1W 88dB
2W 91dB
4W 94dB
8W 98dB

The sub takes WAY more power to drive than highs, because it takes more energy to push air around at low frequencies. For comparison:

Noise Source, Decibel Level, and Noise Effect
0dB = Threshold of hearing
Bell Labs "quiet room" 10dB
middle of desert at night, 30dB
Library, whispering, 40dB
Quiet suburb, conversation at home, 50dB, Quiet
Stocker talks next to sound meter while everyone else is holding his breath, pissing off Navy industrial hygenist trying to measure his electronics shop, 55dB
Conversation in restaurant, office, 60dB
Freeway traffic at 15m, vacuum cleaner,70dB, Annoying
Garbage disposal, freight train @ 15m, 80dB
85dB, Beginning of real hearing damage risk, wear earplugs
Busy urban street, diesel truck, food blender, 90dB Hearing damage in 8hrs
Jet takeoff @305m, outboard motor, power lawn mower, jackhammer, normal car radio at full volume, 100dB Serious hearing damage in 8hrs
107dB, Painful at 2.7kHz
1 sound Watt radiating as a perfect sphere, 4pi suqare meters, 109dB
Chain Saw, auto horn @ 1m, 100W through 2x 6x9 speakers in a car, 110dB
Thunderclap, live rock music in front row, 120dB, Painful
1PSI, 127.5dB
128dB, hair vibrates
Jet takeoff @ 100m, pro DJ system, 130dB
Gunshot by the head (1 sec. average, peaks to 150+dB) 132dB, noticeable eardrum "flex"
Aircraft carrier deck, 140dB, Earphones at high level, painful at all frequencies
Inside a car with 2x 18" pro woofers (high efficiency) 300W each, 142dB
145dB, human vision blurs
Jet takeoff @ 25 meters, 150dB, Eardrum rupture, extremely damaging no matter how short time exposure
Inside a minivan with 20x 12" subs @3/4" travel, 19000W amplifier power, 156dB

From http://www.dangerousdecibels.org/teachers_...ppendices_3.pdf and http://www.makeitlouder.com/Decibel%20Level%20Chart.txt

Edit:

A capacitor IS a band-aid. They cost a lot less than a 200A+ alternator and fatass wires, which is the proper solution. A second battery and a capacitor both have a similar effect: they spread out the voltage drop during a big bass hit. There is a longer-duration, smaller-magnitude voltage drop across the entire charging system when the bass hits and one of these is in place.

I also ran the wires in my door sills, but then removed the back seat . . . because I have a trunk, not a hatch!

 

A capacitor provides a float for the voltage. Batteries take longer to charge. The voltage does not raise imediately on a battery. If you're nipping the very top off the battery continuously, then you're draining it. A capacitor will charge and discharge completely in a matter of milliseconds. This is the difference. A capacitor can reach full charge in the middle of a 20hz wave. A battery takes minutes to recover from a small draw.

Look at it like this. You've got a water pump (your alternator) and a small hose filling a resivoir which is uphill. Every time you turn the switch, the water drains first from the pump, then from the resivoir once the power is exceeded. That small hose represents the charging of your battery. Adding a capcitor is the same as adding a much larger hose off to the side connected to a dedicated resivoir for the switch as an additional resource for it to draw from.

A capacitor is NOT a bandaid. It is a durable tool which will extend the life of your expendable battery and save alot of money in the long run.

Also, I'd really like to see the subwoofer that puts out 88db at 1W. LOL.