Few Q's about wiring

**Joe** · 10-11-2009

My Setup is: Yellow top battery with KnuKonceptz battery terminal, 4ga KnuKnoceptz wiring back to a Directed 750D amp powering (2) 12" 13Ov.2 eD subs (Elemental Designs)

8ga KnuKonceptz wiring back to a SoundStorm F2.200 amp (SOUND STORM | everything else is just noise) was powering stock speakers, but I have CDT CL-S50A components on the way.

From what I read when I bought the Directed 750D amp it is usually underrated so it is probably close to if not more then 600 watt RMS. I was going to have it benched when I was at Elemental Designs but there machine was down at the time.

**Joe** · 10-11-2009

Originally Posted by schroedes

i would also think about increasing the size of your power wire if i were you

What one? The 4ga is handling 600W and should be good up to 1000W, the 8ga is handling maybe 50W max and it should be good up to 300W.

**matt5112** · 10-11-2009

Originally Posted by I800C0LLECT

Key words...."number of reasons"

Tweeters will never be able to handle the power a subwoofer can. My home theatre sub only utilizes about 35watts @ 8ohms. Majority of mainstream subs are designed to handle a lot of power and are very inefficient. There's a number of reasons subs need more power these days...listening preference, design, marketing, spl, etc.

Bottom line is that those sub notes cause a spike in power needs. A poorly designed power supply in an amp will not pull consistantly on the alternator and battery. If his voltage is dropping we don't know why just yet. If he has a 125amp alternator I would be shocked if that's the issue. His amps are rated a little less than mine and all I have is decent entry level equipment. My guess is that the 8awg from the alt. can't deliver on those power spikes and the battery can't keep up either. In these instances a cap can be a band aid. You can try the big 3 as well but like Matt said...this is a science.

Think it through so you don't waste time and effort on nonsense and think LONG TERM DESIGN too.

Powerhandling = Surface area of voice coil x heat extraction mechanisms in place.

Again, caps = 0.03 seconds of power. If the lights dim for even half a second, no cap can aid there. No battery can aid there unless the voltage drops to where it can output current.

Car battery - Wikipedia, the free encyclopedia

This is a chart of the charge level when there is no load on a battery. By this logic, batteries only put out current once the system has reached 12.65 V

Mainstream subs are inefficient because power in a home isn't at a premium and you can only get two of three things, Cost, extension, SPL and to get SPL at low frequencies you need to displace air, lots of it.

Don't bother with any RTA just get REW. Its free, minus signing up for the hometheatershack's forum and their annoying emails saying how they miss you all the time...

Is it not possible that the alternator decreases in performance over time? This I don't know at alll, but is a serious proposition I'm suggesting here.

**I800C0LLECT** · 10-11-2009

Originally Posted by schroedes

why not just save yourself the trouble qand get a cap and do the big 3, i did that but with a much larger system and still have some light dimming,but the voltage barely drops, when you have a powerful system your almost always gona have some dimming, caps provide a ''cleaner'' voltage to your amps

Any amplifier that can hold it's own already has a good power supply designed to take care of "dirty" input.

The only problem with a cap is that once it shoots its load it becomes another draw on the electrical system. At least it waits until power is available to manifest a charge. Until then, it's useless.

A 1 farad cap will only last a fraction of a second powering a 1000watt system that's max'ed out.

**I800C0LLECT** · 10-11-2009

After looking at the situation, if your grand prix really is devised with 10' of 8awg to the battery that could be the potential problem. That's tough to swallow though. I have OEM wires hooked up to my system and it was cranked out today without any issues. I'm running 4awg to the back powering two amps. Perhaps Matt has a point with the possibility that your alternator is suffering from reduced output. It does happen over time.

I guess an easy way to test that is by a big 3 upgrade. But remember, this isn't a fix all. It's a case by case basis. Also, be sure that you're power connections are all tightened down properly and that there is a secure ground point with plenty of surface area touching the frame/metal.

**Joe** · 10-12-2009

Originally Posted by I800C0LLECT

After looking at the situation, if your grand prix really is devised with 10' of 8awg to the battery that could be the potential problem. That's tough to swallow though. I have OEM wires hooked up to my system and it was cranked out today without any issues. I'm running 4awg to the back powering two amps. Perhaps Matt has a point with the possibility that your alternator is suffering from reduced output. It does happen over time.

I guess an easy way to test that is by a big 3 upgrade. But remember, this isn't a fix all. It's a case by case basis. Also, be sure that you're power connections are all tightened down properly and that there is a secure ground point with plenty of surface area touching the frame/metal.

Said 10' for the alt to the starter.... then it would have to go from the starter to the battery, another good 3' proably. I will just try the alt to fuse box wire, if it don't help ill take it off and just wait till something gives out. Always a good reason to buy new goodies

**matt5112** · 10-12-2009

Nice to see my last post was ignored.

Joe: I've measured the voltage drop from the alt to the battery/ fuse box positive. Its about a third of a volt. I lose another third of a volt going back to my distribution block in the trunk. So at the amps I'm at 13.3 V with the alt putting out 14 V at its output terminal.

Dimming in my car is typically noticeable when the voltage drops below 13, say 12.5 V. In the neighborhood of where the battery starts to add current to the system. The only thing that brings the voltage down this low is holding at least two of the window buttons down when the windows are already fully closed or opened. (I realize this damages them hence not doing it for more than a split second if I can help it)

The question is, do you have dimming exactly when the bass hits in your music? Or does it come and go?

It seems like you're asking too much from the stock alt.

My system pulling 100% of its supposed wattage ratings, should be asking for 1080 watts and at 13.3 V that'd be 81.2 amps. That leaves 30 amps for the car to run granted the alternator is putting out its full rating. Which isn't likely considering i keep the rev's as low as possible which means lowest output from the alt possible. Also, when the alt heats up, it puts out less.

Now... Crown, a reputable supplier of pro amps, suggests that severe clipping occurs at 1/3 continuous power output which means my system only draws 27.1 A when running full tilt.

If you're pushing your amps to their limits, they're going to draw rediculous amounts of power and your alt just isn't capable of dealing with that.

If you have a true 650 watt amp and you actually get 650 watts out of it, and its class A/B, its drawing between 1000-1300 watts. depending on the voltage (13-14V), thats 100 to 71.4 amps of current. I'm not sure your car can run on 25 amps, I'm a little doubtful considering how much crap cars have to power these days.

So the real answer would be, get a HO alternator and upgrade the wiring to handle your higher output alternator.

**I800C0LLECT** · 10-12-2009

Apparently me and Matt agree

I honestly can't fathom your hardware utilizing that much power from the alt. I wonder if it's on it's way out the door like Matt suggested earlier?

Also, miscalculation earlier. I had thought that perhaps a cap wired in with the amp would help with it's possible inept power platform. However, caps will only help if they're part of the actual power supply design. Once you move caps outside of that system and wire them as part of the electrical system they do practically nothing to help your system. If you have power problems, new alternators are the only way to go. But you must upgrade the necessary wires to utilize the resulting amperage.

So if you've done everything correctly in terms of solid connections and using appropriate wire sizes & lengths your only other option is to put in a new OEM alt. or an H.O alt.

**matt5112** · 10-12-2009

Getting your old one rebuilt is possible as well if you can find someone who will do that locally. Perhaps get the output bumped up a little at the same time.

**lorenzojay** · 10-12-2009

I have a 12 to 14.4 volt power supply and I hooked my Alpine mrv-t503 amp to it to power my 2 12 inck kicker comps in a sealed box in my house, Just wanted to hear them befor I installed them into the car, Sounded good the most I did draw was between 10 & 15 amps so I was good to go. I also have a 10 inch Precision power dvc flat piston comp sub in a ported box, when I ran this sub I drew more amps than I did running the kicker comps in a sealed enclosure, I ran all 3 subs with 75watts @ 4 ohms. So why would a ported box draw more amprage than a seald box?