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Old 05-08-2019, 06:00 PM   #1
E Coded
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Help with Stealth Stereo install - ground loop issue?

My goal to keep the stock deck for esthetics, but to be able to play music from my phone and charge it at the same time. I prefer hardwire solution over bluetooth.

Parts List
- iSimple JamPort IS3301
- JL CL-RLC: Remote Level Control / Line Drive
- Rockford Fosgate R600X5 5 Channel Amp
- Luke Box
- Old 10" Sub
- Stock OEM Premium Front Speakers
- Stock OEM Premium Rear Speakers
- Black AmazonBasics Lightning to USB A Cable
- iPhone

Here is the break down of how I have it installed:
iPhone -> Lightning Cable -> iSimple IS3301 -> JL CL-RLC -> RCA Cable -> R600X5 Amp -> new speaker wire feed to all 5 speakers.

I am using the constant 12v and the switched 12v from the stock deck to power the IS3301 and the JL CL-RLC. As well as the remote wire to signal the R600X5 to turn on. There is all new speaker wire feeding all the stock speakers, as well as the sub.

I am having issues with engine noise coming through the speakers, so it likely a ground loop problem. I have done an extensive amount of troubleshooting to try and figure it out, but so far Ive had any not luck sorting it out. I have tried different set of RCA cables as well as various ways of grounding the IS3301 and JL CL-RLC - (ground for the stock deck, grounding the stock deck using a wire, grounding at the same location as the 5 channel amp, etc). Below is a diagram of how it currently sits. Does anything stand out that might be causing my issue? Could bundling the RCAs, remote, ground, and speaker wires cause this? Any help would be greatly appreciated.

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Old 05-08-2019, 09:36 PM   #2
bmwman91
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So all of the aftermarket stuff is grounded at a point in the trunk, and the deck is grounded in the stock location on the steering column (or thereabout)? You also tried grounding the deck with the other stuff, at the point in the trunk? Also, is the interference/noise the same when sourcing audio from the stock deck and when using iPhone input (bypassing the deck)?

How are you running the audio signals from the stock deck to the JL box?

I do not think that bundling stuff is the cause for the issues.

Which RCA cables are you using? Most, regardless of price, are poorly shielded. Also, almost everything out there has the RCA shield connected to ground, so even if there is a dedicated ground wire for things, you can end up with currents being sunk through the shields. Some audio equipment lets you choose isolation (open, or maybe 200 Ohms) for the ground/shield. Does any of your gear have this option?

If the RCA's have connectors which you can unscrew and get at the wires, you might be able to disconnect the shield/ground at one end. Get a multimeter and verify that the outer ring on the RCA inputs to the amp have continuity to ground, and then try disconnecting the RCA shield from the plug up at the front of the car by the JL box (or the other way around if the amp inputs have no connection to ground).
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Old 05-11-2019, 08:14 PM   #3
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Originally Posted by bmwman91 View Post
So all of the aftermarket stuff is grounded at a point in the trunk, and the deck is grounded in the stock location on the steering column (or thereabout)? You also tried grounding the deck with the other stuff, at the point in the trunk? Also, is the interference/noise the same when sourcing audio from the stock deck and when using iPhone input (bypassing the deck)?

How are you running the audio signals from the stock deck to the JL box?

I do not think that bundling stuff is the cause for the issues.

Which RCA cables are you using? Most, regardless of price, are poorly shielded. Also, almost everything out there has the RCA shield connected to ground, so even if there is a dedicated ground wire for things, you can end up with currents being sunk through the shields. Some audio equipment lets you choose isolation (open, or maybe 200 Ohms) for the ground/shield. Does any of your gear have this option?

If the RCA's have connectors which you can unscrew and get at the wires, you might be able to disconnect the shield/ground at one end. Get a multimeter and verify that the outer ring on the RCA inputs to the amp have continuity to ground, and then try disconnecting the RCA shield from the plug up at the front of the car by the JL box (or the other way around if the amp inputs have no connection to ground).
Thanks for your response. Great questions.

Let me clarify a few things. The stock head unit does not have an audio signal going through it any longer. The IS330 JamPort and JL CL-RLC are tapped into the stock head unit wiring harness, along with the remote wire to the amp in the trunk. When the head unit is turned on, it powers on all 3 devices. So the head unit is acting as a power switch for all these devices.

If I disconnect the IS330 JamPort, and just pull a straight audio signal out of the JL CL-RLC to a 3.5mm headphone jack device the problem does not occur. It only happens when the IS330 is in circuit -- in my case my phone which is drawing current to charge.

Initially I tried tapping into stock head unit harness for ground, but that was giving me the same engine noise issue. I then tried grounding a wire to the stereo itself using one the bolts on the back. Same issue. Then I tried a random bolt someone under the dash, but again same issue. After spending some time youtubing, someone suggested wrapping a ground wire around the RCA cables and ground it to the stock deck. That didn't work either. Lastly, where I am at now the manual for JL CL-RLC suggests ground at the same location as the amplifier, so I ran a ground to the trunk where the amp is located. But again I am hearing engine noise. I have not tried the steering column ground you suggested. I'll try that next.

One thing I had not considered is at one point the previous owner had an aftermarket deck in there because some of the ground wires were spliced and tapped up. Maybe these wires are not actually being grounded? I will need to check that.

Ive tried a few different RCA cables as well. The first was a relativity cheap amp kit i bought on amazon/ebay (i don't recall the brand) and the others were ones i had laying around from years prior. Can you recommend a brand/model of cable? What should I be looking for? I dont think my auto equipment has the selection for isolation.
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Old 05-11-2019, 08:49 PM   #4
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As far as RCA's, I just ended up building my own from quality cable and connectors.
https://www.performanceaudio.com/can...-rca-plug.html
https://www.performanceaudio.com/can...ble-black.html

Honestly, I doubt that your issue is the cables though, based on the details you provided. Try running a dedicated ground wire from the signal source stuff up front (it looks like you did that based on your diagram, but it sounds like you were assuming the stock harness grounded there?), directly to the lug that the amp is grounded to, or maybe the battery itself. You can do it quick & dirty with the wire running outside the car to see if it works, and then do a more permanent install if it does. I would not trust anything on the original harness, particularly if it was hacked up at some point.
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Old 05-20-2019, 02:49 AM   #5
george graves
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People seem to get speaker "-" and ground confused.
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Old 06-08-2019, 08:03 PM   #6
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Originally Posted by bmwman91 View Post
As far as RCA's, I just ended up building my own from quality cable and connectors.
https://www.performanceaudio.com/can...-rca-plug.html
https://www.performanceaudio.com/can...ble-black.html

Honestly, I doubt that your issue is the cables though, based on the details you provided. Try running a dedicated ground wire from the signal source stuff up front (it looks like you did that based on your diagram, but it sounds like you were assuming the stock harness grounded there?), directly to the lug that the amp is grounded to, or maybe the battery itself. You can do it quick & dirty with the wire running outside the car to see if it works, and then do a more permanent install if it does. I would not trust anything on the original harness, particularly if it was hacked up at some point.
Slight update: I tried a few more ground locations, but I am still getting a slight engine noise coming through the speakers. It's most noticeable when the stereo is on and no music is playing while the car is running.
  • Quick and dirty ground to the battery terminal
  • Stock grounding location behind the clutch pedal

I also tested ground continuity with the stock deck and the clutch pedal ground location and it seems to be continuity.

One thing I forgot to put in the diagram is the amp has a volume/gain pot that is also bundled with the RCA, remote wire, front speaker wires. I have attached a new diagram to how everything is currently wired.

I am not really sure what else to try at this point. Any suggestions?

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Old 06-10-2019, 04:25 AM   #7
george graves
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Sorry - so this is a RPM based noise? Correct?
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Old 06-14-2019, 06:59 PM   #8
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Sorry - so this is a RPM based noise? Correct?


It seems to be. It’s a subtle buzzing sound that increases in pitch as the motor is reved. At some point during all the troubleshooting it was louder and more noticeable.
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Old 06-14-2019, 11:01 PM   #9
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Ground the device that charges your phone at the same point as the amp?
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Old 06-16-2019, 08:49 AM   #10
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Ground the device that charges your phone at the same point as the amp?
He did that initially.

How old is your alternator? Worn components could be causing excess electrical noise.
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Old 06-16-2019, 11:18 AM   #11
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A capacitor before the amplifier will help eliminate unwanted alternator noise. It doesn't have to be a large one. A 0.5 or 1.0 farad capacitor would work just fine.

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Old 06-16-2019, 12:10 PM   #12
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So, do you have noise with the amplifier inputs disconnected?

FWIW, my preferred head unit bypass approach these days is Bluetooth into a Dayton DSP-408. Avoiding a bunch of extra DA/AD conversions and head unit variability seems to produce better results. Also, since bluetooth generally streams in AAC, you (probably) even avoid transcoding/downsampling this way when you’re playing standard iTunes files.
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