So I have 2 amps (JL 400/3 and 500/1). The way I have them mounted, I face two realistic options for grounding:

Option 1: I can ground them to the same point at the shock tower bar, but the ground leads (4-AWG) will be a bit long, on the order of 3 feet.

Option 2: I can ground each amp to the floor of the trunk, and keep each lead (4-AWG) to less than 1 foot (probably 6 inches), but they won't be tied to a common point.

What really is the issue, here (rhetorical)? We want both amps to have the same reference (ground) to avoid ground loops and noise. So which option provides the best (least resistive and inductive) path between the amps?

Now, I've been a EE for 10 years, and from a circuit-design standpoint, a large 'area' of ground is almost always better than a wire, so I'm leaning toward the short leads tied to the trunk bottom.

Having said that, I'm also of the opinion that experience is important. So I put the question to those with more mobile audio experience: Which option do you believe to be the better choice. Please provide reasons. I have the background to understand you.

Thanks in advance

 

Try the short runs. If you have noise just run longer cables to a common point. I was a MECP certified installer for a long time and very rarely had any noise issues with any Hondas.

 

I'm far from being a guru but I'll happily share my experience.

sounddomain.com has an installation forum where you can find many opinions on this subject. After reading several threads there, I decided to ground my 2 amps separately but close to each other. Here is a picture of what I did:




On the left you can see the grounding points for each of the two amps (separate but close to each other). On the right you can see a 4 awg "T" block that connects both amps to the +12V cable from the battery.

I'm not currently experiencing any ground noise but I haven't hooked my sub up yet so I can't tell you the final result. At this stage the sub amp is powering up OK and the amp for my component set is working as well as it did (i.e., no noise) before I made this change.

Hope that helps.

 

How do you have your amps mounted?

 

i did this. actually, i go from two short 8 awg runs to a ground distribution block, then 4 awg from the block to the tower bar location (approx. 3 feet).
no problems. hope that helps.
i hate drilling holes where i don't have to, so i always try to use OEM holes/bolts first, then i move and drill if i have any issues. and it's always easier to start w/ longer wires (3' isn't that long really), and move to a shorter wire.


let me see if i can dig a picture up...

nope, i don't have a pic of this hosted right now.

 

The amp rack is flat all the way across the trunk, with a sub-box integrated into the middle. There is room in the well, around the box, for wiring. The wiring comes to the surface thru two holes in the rack, one on each side of the sub box. The holes are hidden by the amps, which are mounted on standoffs on each side. The standoffs allow all the amp wiring to run under the amps and into the holes, out of sight. Assuming you're familiar with the 300/4 and 500/1 amps, they are mounted in such a way that the connections are toward the rear of the car.

The rack/box is bolted to the car, and I was going to use those bolts as ground points. They would have been under the amps with very short cable runs. In the end (last night) these didn't seem like good ground attachment points (they weren't solid) so I went with the shock tower bar option.

The results: It sounds fine. No noise.

Of course, I followed the FAQ on cable routing.

Thanks for all the replies.

 

glad to hear it went in well, and looks like we may have another Junkie in the house...


of course, here comes the obligatory...

PICS?

 

I would have went for the bolts on the towers also - preferring a solid mount over a close one that could potentially fatigue/loosen.

My 500/1 is actually mounted behind the passenger seat against the wall and grounded to one of the rear seat mounts.

 

I would post pics if I could, but I don't have any web space. I don't imagine I can simply upload them here.

Exactly my thinking as I was looking at it.