knesbitt

I want to run ground from 2 of my amps back to battery. Can I run one 4 Gauge wire from battery terminal to a Distribution Block near amps in rear and split ground into 2 4 Gauge different wires that will connect to amps?

Kale

Ground wire really should not exceed 18" total.

Metal Wulf

and should be a frame ground, not ran back to the batt

knesbitt

I see too many people are having trouble when the connect ground to seat. Ripping carpet up a second time to run wires to battery could be big PITA. Should I at least attempt seat connection?

knesbitt

I refuse to drill holes in car. I have read that as long as gauge is same a positive I should be allright. Who has had problems with grouinding to battery?

GTLocke13

Grounds should be short, and you should never run a common ground between two amps. Doing so will create cross-talk. You want to get the ground to the frame as quickly as possible so you don't get voltage loss in the ground line. The frame has much lower resistance than any type of wire you can fit in your car. It's by far the best way to return current to the battery.

Metal Wulf

:iagree: Do it right

brianw21

Here is the real reason...

Although everyone has probably forgot at some time, electrons flow from negative (ground) to positive.

The reason for keeping your ground short is:

1. That it's the main supply of power for your system.
2. Ground potential differences induce noise.


Distribution blocks have become popular because they minimize ground differences. In fact that is the single largest problem with car audio.

A. Headunit is grounded usually on the firewall or somewhere VERY near the negative path of the battery. This means that the resistance between that ground point and the battery is almost 0.

B. By running ground wire from the battery you will create a resistance with that wire. This means that the resistance of the head unit ground and amplifiers grounds are different.

C. A resistive difference in a electric circuit causes a voltage drop. This difference is voltage and ground path resistance causes an "Anteanna" effect. Thereby letting noise into the system. This is often reffered to as Ground Loop.

Solution: Minimize the difference in ground potentials of all audio components.

This is relativley easy by using a distribution block and a common ground for all components in a close proximity... but the headunit isn't on that block. We don't want to run a wire from that block to the headunit, because that length of wire and it's size would cause a measurable resistance.... So we ground the amps to the frame, which is the largest conductor possible. This makes the relative ground resistance at the amp VERY close to the one at the head unit.

This applies to systems that have common ground connections between the head unit and amplifiers. So unless you are using optical fiber (no electricity) it applies**.

** Even with a fiber connection AI-net for example makes use of a common ground in the signal chain.


I hope this makes sense..

Short Take: You are usign the frame as a massive conductor to minimize ground potential differences.

leolufse

yeah, what he said. :yesnod:

Metal Wulf

:yesnod:

mrkln

Well, I have decided to swim upstream on this one. I have my amps grounded at the battery and have absolutely ZERO noise induced into my system. I have grounded right by the amps on every system that I have built and my current install is my first one that is COMPLETELY noise free. Now expain that. :crazy:

Metal Wulf

It's got to be the lambo paint :jester

knesbitt

can anyone explain mrkln's experience? I also have been told that I can find ground at the locations below. Take a look.





[Modified by knesbitt, 12:48 AM 3/11/2003]

GTLocke13

Actually, the fact that electrons flow from negative to positive has nothing to do with why you need short ground connections. The direction the electrons are physically moving is irrelevant. In fact, when dealing with semiconductors, you sometimes calculate current flow in terms of imaginary "holes" which are simply the absence of an electron.

Any place that there's a reference voltage in a circuit, you have a chance for noise coupling through common impedances. This applies to both power and ground references. The reason you don't get cross-talk on the power line as well is that the DC-DC converter inside the amp (or head unit) has some massive filter capacitors that filter out pretty much all AC signals.

The rest of the post is dead-on though.

Still_Single

:withstupid: I can't explain it, but I can certainly 2nd it! I ran 2 2 guage ground lines all the way to the battery - this is the first system I've had with zero noise of any kind. I know it's not politically correct (I'm not telling others to do the same), but IMHO there's no need to change something that works so well. :flag

0Sales@MVPAutoParts.com

:lol: :yesnod: :yesnod:

GTLocke13

I'm assuming that you ran the ground wire right next to the power wire. This can be a very good configuration because it eliminates any ground loop problems. When a magnetic field passes through a looped wire, it induces a current in the wire. In a car where you've grounded the amp to the frame, if there's space between the power wire and the frame, this acts like a loop, and can induce current in the system. By running the ground right next to the power, you eliminated this effect. You could get the same thing by running the power wire along the frame to the amp. As long as you run a ground wire all the way to the battery right next to the power wire for each amp, and as long as none of those wire runs parallel each other for a long distance, you shouldn't get any crosstalk. However, grounding more than one amp to a distribution block, then running a single wire to the battery can cause trouble if the main wire isn't big enough. One solution to this is to put a capacitor from the distribution block to the frame. It doesn't have to be an audio cap. A standard industrial 10,000 uF cap should do it.

kittmaster

While I tend to agree with most of the rational on this thread, I'll be the odd ball. I ALWAYS run a direct positive and negative lead directly from the battery to the amps and processors. WHY? Because all the rest of the car electronics are dumping to ground somewhere and ULTIMATELY end up to the negative BATTERY post. With all that electrical noise within the ground loop itself from other parts of the cars electronics it can pick up ground bounce and signal refraction from the noisy microcessors digital grounds. The ONLY detriment is possibly a .1 (maximum) of a voltage drop from the battery to rear of car, assuming that 4 guage or lower is used to make the connection. I teach electronics for a living and install $100k systems, trust me, if you can swing the cost this is the best way to do it. It guarantees noise can't creep into the system ASSUMING all components do not touch metal of any kind including the antenna to create a ground loop. No ones opinion will sway me from this position so keep your flames to yourself. This is the advantages to having a PhD in electronics..... :yesnod: Don't believe me go to my website and see for yourself under the pictures "current kitt pictures"

Kitt

GTLocke13

The more I think about this, the more my position changes. Running the ground through the frame causes excatly what you're trying to avoid: a common ground resistance. A dedicated ground line for each component should minimize the noise in a system.

That idea of a filter capacitor on the ground of the amp is pretty good too, I think. I may try that on my system sometime.