odd radio static after amp (15 Tacoma)

2015 D-Cab non JBL Tacoma.

2 weeks ago I swapped to JBL GTO 6x9's up front and 6.5 GTO's in the rear, stock tweeters still. Sounded fine, no noise just not the clarity you can get from a amp'ed unit. KEEPING THE STOCK HEAD UNIT.

A few days ago I wired in the amp. A 4 y/o but fine kenwood 4 channel I had in my old green Taco. I have wired them before but I am by no means a audio genius, though it isn;t at all difficult. I soldered and shrink wrapped all 8 pairs of wires running between the head unit, amp and speakers with 16g pure copper (good wire with thick insulation, excluding the factory leads). Made sure all the pos/neg's are right but at the speakers I may have flopped the front on accident at the speaker (though I have never known that to cause noise).

PROBLEM
When using the front speaker wires from the deck to the amp, every speaker I send the signal to (when testing it out in each speaker) sounds great. Very little electrical noise, clear sound. But when it comes to the rear speaker leads FROM THE HEAD UNIT TO THE AMP, there is a crap load of noise. It doesnt matter if I send it to the front or the back speakers. I just pulled the stuff to check on it, verify I didn't swap anything, it all checks out. I have not fiddled with the gain on the amp but because BOTH of the BACK SPEAKER head unit to amp leads cause relatively equal amounts of interference no matter what speaker they go to, it leads me to believe there is something else going on.

This is not alternator buzz, this is just static noise that doesnt change with volume whether the engine is running or not. I suppose I can do a little more trouble shooting becuase it seems worse when all speakers are hooked up.

WORDS OF WISDOM, ANYONE? Much appreciated!

I did read a post I found that basically says 0 the gain with volume down then raise it until you hit a intolerable level of 'noise' then back off a tad. I havent messed with that stuff yet since I felt like it was a amp-independent problem. But it is worth a shot.

 

do you have any LED lighting? fogs, Headlights , LED bars, LED lights cause static sometimes in weaker FM band stations or AM stations.

 

Truck is otherwise bone stock. No additions. This is on any radio course.

I fiddled with the amp settings. In 100% MONO there is no noise but the speakers are weak in the back, fronts are unaffected. When I turn the dial more toward STEREO, the rear speakers get louder but the noise goes up drastically. Could this be an amp problem? I tested the leads, seems the source is 3v, 3v, 9v, 9v for the 4 source wires from the stock radio but I dont remember which ones were which. Could this be an inherent problem that two of them have to get amped up a lot therefore noise goes up? Anyone had amp problems like this?

 

Well for those that care, it turns out that the source of the elusive 'hiss' is the head unit itself. Its bad enough that I disconnected everything to the amp. Kinda blows that I spent about 120 making that harness. It is probably because the HU puts out line level output, where as amps are generally suppose to take preamp outputs so noise gets amplified more.

I am looking at HU options now such as to not necessitate a 4 channel amp but only ones that can use wheel controls and all the factory shit. I couldn't get myself to buy a sound processor for 200 bucks+ and stick another chunk of metal under the seat with more wires.

So in closing if anyone is trying to keep their stock HU and replace the speakers and run a 4 channel amp, I would advise against it. The HU fuzz sucks.

 

I care, Kyle.
2006 DblCab PreRunner Taco
Just upgraded to a kicker package all around, kept stock tweeters, with a 4 channel amp, kept my stock head unit, and unfortunately didn’t read your post beforehand...
I’m getting the fuzz you’re talking about, it’s most noticeable at volume 0-6 but it’s also noticeable when the head unit is completely off. Not as loud as when it’s on, but it still fuzzes when it’s completely off.
Was this also the case with yours?
I took it back to the place who installed me and they basically just told me it was amp noise, what a load of BS. Took it to another place and they said it could be a bad harness behind the head unit.
Is this basically what you’re talking about in where the problem lies? The stock head units are line as opposed to preamp?
Please advise, much appreciated.

 

I'm old school. Back in the day, low level or line level referred to RCA type connections and high level referred to speaker connections.

It's always better to run low level from the head unit to the amp. Think about it, with high level inputs, your taking an already amplified signal meant to go to a speaker and amplifying it again with all of the original noise and distortion from the head unit amp. I made this mistake once and it made a pair of a/d/s 300Cs sounds like crap. Same thing goes for line out converters. Waste of money imo.

The factory hu in my 06 has pretty much zero channel separation. The Kenwood i installed a month ago... Omfg. There's a world of difference. Even with the crappy stock speakers. It has no depth of stage though. New speakers should address that issue. Warm weather project...

 

Yea I think we’re on the same page there. Do you think that would address the presence of fuzz when the head unit is completely off though?
I’m starting to have a feeling it might be something else. I’ve had a buddy of mine tell me it could be a bad high/low adapter, I think that would explain the fuzz when the unit is on. He also said it could maybe be a bad kill wire (is that a thing? I’d never heard of it before) on the head unit, and I guess that would explain why I get the fuzz when the head unit is completely off.
I did notice my amp power light stays on even when I turn the head unit off...is that normal? Or is it supposed to be off? Maybe that’s the kill wire my buddy previously spoke off... (???)
Any of this sound in the ballpark?

 

I'd do what i can to eliminate ground loops. Single point ground for everything.

Pull the remote wire off the amp and see if it stays on. Some amps sense a signal and turn on automagically. If that's not the case, then, make sure that wire is switched somewhere. Does the line out converter have a remote turn on wire as well? Switch both.