HELP! High Level Input Amp Setup, 2 Channels Don't Work Right

[eggwardo]

I have a 2011 Jeep Wrangler with the stock (RES) Radio. It has super low wattage so i wanted to boost the power with an inline amp. I got a soundstorm F4.400 (sorry i can't post a link). I hooked it up with the high level inputs. Basically running the speaker wire to the amp then back out to the speakers.

Upon turning it on i found that the front speakers, which were channels 1 & 2 were very horrible sounding, quiet and very very distorted. The back speakers (channels 3 & 4) sounded great. The first thing i did was switch the inputs so wires that were going to the front speakers now went to the back. This moved the problem to the back speakers. So i know it's not an amp issue, it's a wiring issue.

I figured since it's both speakers then it must be a grounding issue. The amp uses 2 little wire harnesses for the inputs, one goes to channels 1 & 2 the other to 3 & 4. There is also a ground on each of them. So i checked the ground for the bad set of wires, even replaced the extra wire i added to it and this did not fix the problem.

I'm thinking that the problem has to be in the wiring harness. Possibly the ground wire isn't getting a good connection. But i really don't know.

Oh yeah, here's an interesting tidbit. Right now i have just the 2 channels that sound good hooked up. But when i put the fader all the way so they should be off they get real quiet but real distorted. Like how the other ones sound. I'm thinking this might be a clue to the problem.

I'm going to call soundstorm in the morning to see if i can get them to send me another one of those wiring harnesses. But any input on something else that could cause this issue would be greatly appreciated.

thanks, eric

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[eggwardo]

i disconnected both of the grounds for the little wire harness things. And nothing changed still one bad and one good. So that cancels out the bad ground theory, but doesn't cancel out the bad harness theory.

I also rechecked my wires to make sure i didn't mix anything up in the routing of them. No luck with that either.

 

[eggwardo]

99% sure it's the harness. I cut one wire and the other speaker started working perfectly. Redid both wires for the speaker i cut and the problem was still there. If i put the harness in crooked i can get either the right or left speaker to work correctly but not both at the same time. There must be a short across a couple terminals.

In case someone else finds this post in the future I'll try to post an update when i get the new harness, but if i forget and this is the last post then that means the new harness fixed it.

God what a PITA. I've spent hours checking and rechecking this stupid thing.

Anyway, thanks for looking.

 

[eggwardo]

Ok that wasn't the issue. I got a new harness and hooked it up and nothing changed.

This was a few weeks ago so my memory of the whole thing is kinda fuzzy. I went on vacation so i left it alone for a while.

I'm going to be referring to just the front 2 speakers here. And the wires i'm referring to are all BEFORE the amp. So when i talk about connecting speakers i'm actually talking about the wires out of the head unit that would go to the speakers but now go into the amp.

So here's what happened. I hooked up the new harness to the speaker wires. Very careful to get all the wires connected to the right wires. Both speakers were quiet and very distorted. So i disconnected one of the wires to the left speaker (don't remember which one) and the right speaker started working perfectly. So i fiddled some more and figured out i could have either speaker working right but not both. SO for some reason i tried hooking the speakers up "backward" (negative to positive). Didn't work. BUT i unhooked one of the wires to one of the speakers and both speakers started working correctly.

So i have one speaker hooked up "backward" and the other with only one wire going into the input of the amp and both speakers work ok. The balance and fade both work correctly too.

I'm having a hard time making this make sense to you guys so if you have questions please ask.

But my question is what could i possibly have done wrong?? This seems so simple but i must be missing something here.

I talked to a guy at Best Buy and he said something about too much impedance or accidentally connecting the speakers in series. I don't know about impedance but connecting in serial don't seem right since the balance and fade work correctly.

Any thoughts you have would be greatly appreciated.

 

[brandinooooo 10+ year member]

I bet your speakers are 8 ohm and your amp output is 4 ohm and 2 ohm.

That may be your problem. If so, youll need new speakers or a different amp.

 

[keep_hope_alive Premium Member]

you can wire 8 ohm speakers no problem and you won't get distortion. output will be reduced and distortion will decrease, damping factor goes up, etc. nothing wrong with 8 ohm speakers. since you can get them to work by disconnecting one high level input wire, it's not an impedance issue.

somewhere, you're shorting signal to ground. maybe the internals of the amp are shorting the head unit output to ground or connecting the negative speaker wires together. most head units don't like having grounds tied together and will distort as you describe if that happens. by connecting only one wire, the HU output isn't shorted and both channels get a signal.

or maybe you have positive and negative mixed up on the front outputs, and the amp is tying positive to negative which the HU doesn't like. that would explain why you can move the problem.

you can use a DMM to measure resistance between amp high level input pins and chassis with everything off. none of the pins should be internally connected at a low resistance, i suspect the left and right negative inputs are connected.

a decent line output converter could solve this issue.

FYI - it's not safe to play with connections while the equipment is on. it sounds like you are touching and cutting wires while the HU is running. that usually results in damage.