Engine whine and ground loop fixes... take two

[darrendriven]

Hey guys, lifelong car audio nerd but new to the forum. I'm stumped and need help.

Problem vehicle is my 2017 Jeep Wrangler that had the factory Infinity upgraded 9-speaker system.

Head unit: Joying 7" Wrangler kit (I basically use it for wireless CarPlay and am happy after ~1 year)
Front/Rear Amp: 4-channel Kicker CX360.4 65wx4
Sub Amp: An older beefy Phoenix Gold Ryval I had laying around
Interior Speakers: Kicker CSC67 (x4) + OEM Infinity tweeters
Sub Speakers: a pair of Phoenix Gold RSd12d in a homemade box

Step one: Upgraded factory head unit with the Joying (harness included, plugged right in) and upgraded all four interior 6.75" speakers with Kicker coaxials. Added the new Kicker amp under the passenger seat with 8 gauge power coming from battery. Grounded solid within 12" of amp. Two sets of shielded RCAs (F/R) from head unit to amp. (Kept the factory Infinity sub for the time being.) Definite improvement. No issues.

Step two: Decided to use the subs and amp out of my last rig. Jumped the power from amp #1 and ran to rear of rig. Grounded within 18" of amp. Single shielded RCA from head unit to sub amp. Now things start getting weird. After starting a song with some good bass and turning it up, I sometimes get an echoing throbbing bass sound (whump whump whump) from the subs, and it lasts 5-10 seconds after I hit pause on the music. Hmmmm. More troubleshooting... I turn off the crossover and now I realize that I can hear a nice hum when the engine is running and clicks/pops when turn signals blink, etc.

More troubleshooting. Sounds like it might be a ground issue or maybe low-voltage. Nope. I run a ground wire and link the head unit to each amp. No help.

So here is where I am finally stumped:
- The main amp ALSO has noise through all interior speakers, but only if I have RCAs connected to it and unconnected at the head unit end. The moment I attach them to the head unit the noise disappears. (I tried an external set of RCAs to eliminate magnetic interference and the same symptoms happen)
- The sub amp only has noise when it the RCAs are connected to the head unit (I connected my MP3 player into the sub amp and it sounded beautiful so it's not the amp)
- The head unit was my suspicion, so I ran 12V/ground to it directly from the battery and then output the RCAs into a boom box... no interference noise. (I tried a $15 line conditioner and as expected, no improvement)
- Plugged the powered boom box into the subwoofer RCA at the back of the rig... interference is audible. (Tested using a different RCA cable strung through interior, can still here interference through sub signal)

I'm really baffled. Tomorrow I am going to try running a new power cable outside of the vehicle... maybe somehow the power cable is transmitting something? And it's connected to both amps.

 

[Jimi77 5,000+ posts]

Seat bolts tend to make poor grounds. Amps grounded at different locations can lead to ground loops.

You might try tying all the grounds together. Try grounding the rca jackets at the hu.

 

[soundup11]

Great information!

 

[Audiojunky413]

Alrighty guys, since we no longer have access to the other ground loop fix thread, thanks to someone (you know who you are), I'm making a new thread about it.

Ground loops and engine whine cause common problems such as a high-pitched whine that varies with engine RPM's, various thumps while changing tracks, turn on/off thumps, etc.

There are various protective measures to take in order to decrease the likelihood of experiencing engine whine and ground loops.

• Shielded RCA's
  A good pair of shielded RCA's may be the easiest way to avoid engine noise. Don't use patch cables or other el-cheap-o RCA's that are unshielded. I'm not saying you need to invest a small fortune in RCA cables, just make sure they are shielded.
• Proper head unit ground
  This is perhaps the most common source of engine noise. Many times factory head unit grounds are poor. Relocating the ground wire or adding to the existing one will help reduce or eliminate ground loops.
• Proper amplifier ground
  If none of the above have worked, check the ground for the amplifier. Make sure it is grounded to the frame, battery, or other substantial metal surface. Make sure the metal is good 'ol fashioned detroit iron. Many cars use metallic alloys or composites that aren't very conductive. Avoid those at all costs.
• Wire routing
  Some claim this next fix is BS, and others swear by their grave that it works. But run your RCA's and power wires at least 18" apart. I route my RCA's on one side of the car, and power on the other. Couldn't hurt.
• Grounding the RCA's on the head unit
  Many have had problems with Pioneer head units because of a poor internal RCA ground. To remedy this, simply wrap wire around the RCA's and screw the wire down to the head unit's chassis like so:
  
  
  
  
  Thanks to Ultimate157 for the image.
  To view his thread on this subject, click here.

Please note: While ground loop isolators are tempting to use as a quick fix, I generally don't advise people to use them because they simply cover up the problem instead of solving it. Only use ground loop isolators as a final resort is none of the above fixes work.

Enjoy //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

I have a grounding noise but hard for others to here my amp is good for sure I just don't know if my battery in my trailblazer ls is a cause of the ground or if I need to ground it elsewhere? Any idea of where I should ground my second battery? It's in the back next to my box . Thanks in advance

 

[JohnPD]

I have a grounding noise but hard for others to here my amp is good for sure I just don't know if my battery in my trailblazer ls is a cause of the ground or if I need to ground it elsewhere? Any idea of where I should ground my second battery? It's in the back next to my box . Thanks in advance

Your battery itself wouldn't be the cause of a bad ground, but where the battery is grounded to could be the cause of a ground loop noise.