i would ask /o/, but i think more expertise would be here. I'm

>>1221103
The car chassis. You just find a spot that is a. nearby and easy to get to b. has clean exposed metal c. protected from moisture or dirt and d. allow a secure connection.

>>1221104
this. where those seats bolt onto the floor should work.

>>1221103
The ground for a house almost certainly works differently from a car. A home ground is literally dirt. It takes a decent bit of effort for charge to go from A to B, so it makes it possible to get a clean signal by spacing out your grounds.

A car chassis is highly conductive, causing charge to quickly distribute evenly along the chassis, so it almost certainly doesn't matter where you ground at.

>>1221120
Forgot to mention, but you only care about the ``quality'' of the ground when you care about the cleanliness of the signal. You're getting all your power directly from the DC battery, that's as clean as it gets.

>>1221121
>You're getting all your power directly from the DC battery, that's as clean as it gets.

This is true as long as your engine is not running.

When you engine is running this could not be more wrong in every way.

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The bolt where the negative battery lead connects to the body is the place if you want to be pedantic with star earthing.

Practically speaking I'd go a seat mounting bolt and use an audio isolation transformer if needed.

>>1221121
Given that ground is half of what supplies power to the audio amplifiers, I imagine you probably would care about the cleanness of the signal.

>>1221103
fitted a amp to both seat bolt and to the seat belt bolt and had no problems, make sure to use some steel wool or such to rub of any paint or coating on the bolt/hole to help

>>1221103
Use a wire wheel on any and all paint to the seat bolt, on the bolt, the car body, the bottom of the seat bracket, etc. Get that shit shiny. Little air die grinder or dremel works best. Can slice the carpet with a razor blade and glue it back down if you need.

Crimp a good end on your ground wire, and cover it and all contact points with "bulb" or "contact" grease and snug it down good.

Watch the heat if you are just throwing it under a seat.

Should be mounted secure but i have been known to just bolt 1 inch spacers on the bottom of cheap amps and toss them under the seat.

Good luck anon

The way I do it every time:
Unbolt seat
Place amp under seat
Run cables
Use a grinding disc on a dremel around one of the seat bolt holes to expose bear metal
Use that as a ground with a loop crimp of whatever they're called

The pic was just a stock pic, my amp is going into trunk, but I can snag a rear seatbelt bolt if that would be best.

But I'm still not clear if I should be testing it somehow to establish if its a good ground (enough) point.

>>1221122
this is the kind of stuff I would find when searching for answer. Half-answered declarations with no clarification.

>>1221275
If its part of the main car body if should be good enough.

If you really must test it ground 30 amps worth of lights to it, power them up and measure the voltage between there and the battery cable earth bolt. Lets refer to this as the autism test.

>>1221311

ok, so if its like an amp setup less than 1000 total watts output, i just need to worry about a fat cable, not placement?

>>1221311
>If its part of the main car body if should be good enough.

Cool. I can attach to any piece of main body work and the path back to the battery will be close to zero ohmage, and it would be autistic to actually verify this. Awesome.

Learn new shit here every day.

>>1221311
>Lets refer to this as the autism test.

Since when is it autistic to verify something?

derp, some anon on 4chan said it, so I did it. fuck. why didn't it work like anon said?

>>1221103
Depends on what you plan on doing anon.
If it's just a small amp to give your ride a boost then you can use any convenient bolt/seat mount/etc.
However, if you are going for a larger amp then you really should run both power and ground back to the battery. Use a proper circuit breaker for the power cable because if it shorts you are going to start a fire.
As to the gauge of wire you need..
Go here. https://www1.crutchfield.com/learn/learningcenter/car/cable_gauge_chart.html
Fairly easy to understand.. but just in case..
The further you go, the more power you need, the larger that cable has to be. The ones I use are 1/0 and those power a distribution block that in turn feeds a 200W and 400W amp plus the crossover and fans. These days that doesn't sound like much, but the system is capable of making you deaf in less than a minute at full volume. It's all in the design.

And on that.. You will find things that buzz when the bass hits. Look for stuff like deadmat or dynamat. You just use a small bit stuck to the inside of door panels to stop the vibration.

Enjoy your hobby anon. I sure did.
had to stop when IASCA changed the rules and it put me at the lower end of my power class.

>>1221311
Here is the problem with that.
The battery ground is normally connected to the fender and the engine. The engine has a strap to the chassis. Modern auto electronics run a separate ground back to the battery or join up on the fender bolt. Very few systems use a chassis ground these days.
If you pull a ground from elsewhere you also get the noise that gets onto the body. That noise gets amplified. Yes, you can put a Cap in there (sometimes called a stiffening caps) That helps both cut noise and give that extra bump for higher demands.

That being said, I have run a few things via the chassis ground. It works but is not optimal.

>>1221387
>Since when is it autistic to verify something?
when the thing you're verifying is "do the metal parts of my car touch eachother?", a thing you've verified every time you drove and the car did not break apart

>yet another thread where americans don't understand the difference between gnd and -

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>>1221467
>yet another foreigner who doesn't understand americans

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>>1221104
Yep.
>>1221118
>where those seats bolt onto the floor should work
Yep.
>>1221191
Also good suggestions.
>>1221192
>loop crimp
Ring terminal.

Power under the door trim to the back on teh battery side. Fuse that wire close-ish to the battery, mount the holder on the frame/firewall/wherever. Protect that cable between batt and fuse.
>Pic related
While you're in there, get some battery terminal cleaner/protector and a battery brush, clean off the batt terminals and connections on the cable. (That's the red stuff you see on the post.)

Signals all go under the door trim on the opposite side of the power cables.

Then pretty much just connect that shit up.

If you don't have a lot of alternator output or battery capacity, you may consider adding a capacitor for the amp. With dual-batteries and a 220 amp alternator, my electrical system's sufficient without one.

10-20ft of split loom really helps protect the wires and cleans everything up, makes it look nice.

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Power and remote turn-on comes in from the top, behind the seats.
Ground is on one of those seat belt bolts underneath.

Used the terminal block on the amp to feed the two-way, since I had good power back there for the amp. I'm never using both at once, radio draws a few hundred mA when receiving, up to ~5A on tx-high.

L/R from the headunit to the amp (RCA cables), ext.spk and mic/control-head data for the two-way all run to the back corner, then under the door trim to the dash.

>>1221471
i understand what you are trying to say, its just technically garbage nonsense.

>>1221485

Read the text on the bottom of that pic.

>>1221490
read this text: fuck you.

>>1221471
the negative of the battery is connected to the chassais making (a poor) connection to the negative of the battery availably as well as providing corrosion resistance to the body by replacing lost electrons.
has nothing to do with grounding anything in any sense whatsoever.

Voltage drop test.

Set your multimeter to dc volts. Connect one lead (doesn't matter which) to the negative post of the battery. Connect the other lead to a suspected ground. The closer the meter reads to zero the less resistance between the battery and the suspected ground.

Caveat: voltage must be flowing through the ground path.

>>1221103
i always grind a bare spot under the carpet and run a self tapping screw right in. done many times in many cars and have never had a fuse blow or problems with power this way.

>>1222230
>: voltage must be flowing through the ground path.

that's what I hate. I try to get the amperage to flow but the fucking voltage takes up all the room.

>>1222418
>amperage
>trying to nitpick others
>uses meme words