car audio
 

I'm redoing the system in my van. I'll be running 50x4rms amp and a 1000x1rms(at 1 ohm) amp at .75 ohms, so I figure my rms wattage at about 1500.

Now, the mids and highs will be high passed at about 80hz so I doubt the 4 channel will pull anywhere near its rated power.

My question is: will my stock electronics take this or be able to dish it out?

I've got a 100amp alternator, thats only 1440 watts w/o efficiency losses or factoring in the vehicles electrical needs. Is it all about the battery? I have a v-8 and live in MN so I always get the biggest battery I can get (I beleive 900cca?) but have no idea what the continuous discharge would be. (I know it will only pull max current during bass peaks)

It's not worth doing if I have to add a battery, and also not worth doing if the vehicle cannot meet the systems electrical demands.

make sure you use a capacitor and everything will be fine. i would say at least 2 farad but more is always better. i run 8 farad on around 1200w. caps are pretty cheap on the feebay

Lights will dim out on long deep bass notes but otherwise should be no problem. I ran a a 2400W Orion amp in a Grand Cherokee with a 1 farad cap only dimmed lights when I was showing off. I wasn't running the amp at full capacity but it was still enough for a 140.1db rating and a 136.7db averaged over 30 seconds, placed third in a large competition

dude for runnin serious amperage u oughtta upgrade your alternator...otherwise ull be clipping like a mithafvcka...
also do the big 3 under ur hood...

You should be fine I have installed since 87' and have a degree to back it up. Unless you are jammin hard (like setting off car alarms everywhere you go), you will be fine. Back in the Day one of the systems I ran was a Autotek 7600(300 X 2 @ 4ohms) bridged on 2 Kicker 8ohm 15's for about 950 watts, a 7150 (75 X 2 @ 4 ohms) on a pair of 8's and a 7204 (50 X 4 @ 4) on 4 sets of seperates).

The car was a 78' Buick LeSaber with a 68 amp alternator and a 850 cca battery. The only time I had any trouble was on sunday morning (after cruising Friday and Sat night) the car would be dead and I would have to jump it. After 3 times I added a second battery.

Caps are for posers. They don't do squat sometimes they might keep your lights from dimming but that's about it. They only store small amounts of energy that already came from your system anyway.

Jeff

You gotta put in what you take out. If you are pulling 1000w, you gotta put in 1000w. If you are using a second or third battery, it just means you'll be able to run longer and the voltage dips will be lower, but the alternator will still have to put it back in.

However, I think you'll be fine. Music is dynamic, so you probably will only be pulling 300w average most of the time, with 1200w total peaks when bass hits, unless you like listening to bass sine-waves. Actually, music is logarithmic; to get twice as loud, you need 10X the power. Once you get to a certain point, the power required to get louder is just stupid.

Whatever you do, DO NOT skimp of the enclosure design. Get the Theille-Small parameters for the sub(s) you plan to use and select the right box type (ported vs sealed) and build it/have it built properly. Most speaker companies tend to advertise using smaller box than ideal. And some car shops will just throw the speaker into whatever they happen to have in stock and say that it's fine. Calculate it yourself for the best results. A box can make a crappy speaker sound decent, but also a great speaker sound crappy. Don't clip the amp, get the proper box, and you probably won't notice a difference between a $100 speaker and a $500 speaker. And you'd be surprised how little power you actually need for good sound when everything else is done right.

And about the caps: All they really do is help keep the lights from dimming on punchy bass. If you like bass CDs (long notes), then it will not help since they drain more quickly than the bass note is playing.

What sub are you going to be running? Sealed, ported, or by-pass box? I'm assuming you're going to run dual 2-ohm in parallel, or running more than one sub in series/parallel? If you felt like paying for Kenetiks battery you wouldn't need a power cap, but that's like comparing a HC motor to a Neu in terms of price.

wow no one uses caps huh? thats too bad. want to see how much energy they store? drop a nail across a charged cap and see what happens. people die from capacitance not that its relevant. also BrianG hit the nail on the head, box design is everything, it will make or break your bass for sure.

Who said that no one uses them? I know how much power is stored in one. I also know that it makes no difference on a system other than slightly lessening the voltage sag so that only lighting is not as effected as much, sometimes... I have worked on amplifiers and know the ins and outs of a power supply like not very many people. Surprise they are a lot like a standard brushed ESC.

The path that the energy has to travel through an amp is first to it's own bank of input caps, that energy is switched by the power fets for driving the primary winding of the transformer (one side) and then is induced into the secondary winding of the transformer where the voltage is stepped up, then through a set of diodes into another bank of caps to form one rail for the amplifier to feed off of, if you really want to make an improvement than the secondary side of the amp is the place. I have done it and it makes a much larger change there.

When they "came out" back in the mid 90's I tried them and saw that they were worthless as tits on a boar hog as my Dad would say. The only song that it made any kind of difference with was AC/DC's "Thunderstruck" and that was with 2 1 farad caps and the voltage drop was 1V compared to 4V before on a digital storage O-scope.

People die from capacitance? Not with the ones used in car audio, you would have to be in the perfect storm of events for that to happen. Edit: It takes between 50 and 300 Joules to kill a person and a fully charged 1 Farad at 14.4V will store 103 Joules.

Brian did hit the nail on the head just look as Bose they used the worst speakers I have ever seen and they sound pretty damn awesome for a speaker that came out of an 80’s TV.

Back to the original question you’ll be fine. Like Brian said the amount of current drawn in dynamic. Just with the music at a high listening volume you will probably only pull about 30 amps average.

Jeff

when you put it that way it sounds good. guess im a victim of my own ignorance. never used anything smaller than like 5 farad in the autos, at work its Kvar and 4-16Kv. even bare wire or UG cable has capacitance capability. as they say "it will knock your d*** in the dirt" usually its only the cap banks that are lethal, but i have no doubt a blast from a good sized car audio cap [I]could[I] kill somebody but your probably right with the math. it might just make you wish you were dead for a minute or two.

and who doesn't LOVE paying a buttload of money for paper cone speakers? .....

A car audio cap of ANY size will not hurt anyone in the slightest no matter if it is 1pF or 1000F. It take current to hurt/kill, and ~12v cannot generate enough current through your body's resistance. A large cap will just take longer to discharge. The voltage is too low to do anything except give a good tingle if you put it on your tongue. And a cap can only be charged up to the supply voltage. Slim; now if you are talking about those "starter caps" you see on electric motors, or some found in CRT TV's (especially larger screens), then yeah, those can hurt/kill you because they are charged with voltage in the 100's.

Case in point. A long time ago, the shop where I worked had a spot welder that was basically just a transformer rated for 1.5v but at over 1000A. On a dare (because I knew what would happen), I put my finder in between the jaws and turned it on. Of course, nothing happened. The spot welder would be like putting 500 AA's in parallel. Actually, the open circuit voltage measured closer to ~5v unloaded IIRC.

I will have to agree with some of the above and say stay away from capacitors in car audio aplications, there are far better and more practical options out there. I would suggest instead to simply add another battery or better yet a "power cell" designed for the rigors and discharge rates associated with high end car audio.

To back up my claims i will tell you to look at the worlds loudest vehicles. I bet they aren't using capacitors, there using insane amounts of high quality batteries or power cells.

Now obviously these guys are taking things to the extreme, but they prove that batteries/power cells are the best way to supply the current demands of car audio systems

At the voltage levels you are talking my all means that can kill you. If you have a 10 micro farad cap at 10,000V that is 500 joules. The voltage at that point is enough to overcome your body’s natural resistance, and that varies depending on a lot of factors. I have measured my own resistance as high as 19M and as low as 540K.

I have been shocked by a Punch 45 (circa 92’) on 1 channel and that's only about 10V RMS (little over 14V Peak 2 Peak). Yet the only time I have been shocked by a battery is when wrenching on the + terminal of a battery while sweating and wearing shorts with my legs on the bumper. It took me a few times to realize something sharp was not poking me. Not even working with small aircraft batteries (24V) have I ever been shocked. It takes close to 50V DC to give you a shock (less in some cases).

Jeff

Wow, 10v? Body resistance must have been very low to feel that. I can't remember the exact amp I was using (I think it was an old PPI PC2350 - 2x350w@4ohms) but I could only feel a slight buzz and that was at ~60vrms AC on the speaker wires in bridged mode.

Most people don't realize that it's the body's own reaction that kills them most of the time. It takes ~15mA (that's 0.015A) to severely hurt/kill you. Example: Take 120V. If your resistance is ~15Mohms, that's only 8uA (0.000008A). Ok, so you feel it, but it doesn't harm you. But, the body's reaction (heart pumping faster increasing circulation closer to the skin, sweating, etc) all lowers the body's resistance, which makes you react more, which further lowers the resistance until it gets to a point where that magic 15mA can start flowing and that's where the problem lies. If you could remain totally calm and somehow keep your body from reacting in this way at all, it would theoretically take 225,000V to kill you (assuming 15Mohm body resistance and exactly 15mA to be fatal).

Edit:I am sure it wasn't (or is ever) cool around here so it was probably fairly low.

Come to think of it, the truck had 2 45's bridged each on its own 15", so I guess that would have been closer to 20V RMS. I had each lead in a hand and we were trying to tell if they were out of phase on the first startup, so I had it up pretty loud. I used to work on those series of amps (among others) extensively. That was back from the transition from transistor based switching power supply to MOSFET based power supply.

Jeff