03 with Rockford Fosgate system head unit replacement - weird sounds - Nissan Xterra Forum
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#1 Old 12-28-2011, 01:34 PM
Volanova
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03 with Rockford Fosgate system head unit replacement - weird sounds

So I just wired up and plugged in my new JVC KW-HDR720 head unit (http://www.crutchfield.com/S-1h5FMA1...KW-HDR720.html) in my '03 with the Rockford Fosgate sound system, and I've noticed that I now have a repeating low-tone thumping noise that comes through the speakers when the vehicle is turned off. It seems to go away when the ignition is set to on. I noticed that it goes away when I unplug the speaker jacks from the back of the head unit, but I'm not sure if it's originating with some. The fact that it only happens with the ignition turned to off makes me wonder if maybe it is the security system interfering (it's a stock security system so no idea on the specs/wiring). It does, after all, have a flashing light, so it may be sending out some weird signal whenever it goes off.

Anyone else heard this?
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#2 Old 12-28-2011, 04:20 PM
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Are you hooked into the factory amp?
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#3 Old 12-29-2011, 08:59 AM
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Yep, it routes through the factory amp using the adapters provided by Crutchfield.

I decided to just pull it out and pop it back in, as I realized I had forgotten to disconnect the battery last time. So, I did that, this time correctly disconnecting the battery, and the background popping while the ignition was off went away, but it was now popping whenever the radio engaged or disengaged the sound. For instance, if I turned the volume all the way down, it would pop when I un-muted it, or when I switched equalizer settings. I called Crutchfield, and they said it was a known problem with head units that have RCA jacks in the rear being installed in Nissan vehicles with the Rockford Fosgate system, and that installing a ground loop isolater would fix the problem. They were kind enough to ship me out a new one free of charge!
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#4 Old 12-29-2011, 09:24 AM
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Let me know if that works for you. I tried everything I could to stop the noise(s). The only thing that stopped it was running new wires to all my speakers and doing away with the factory amp all together. From what I understand there isn't a internal amp in the RF head unit, it just sends the signal like a rca line to the amp behind the HU. Once you hook up a new HU that has an internal amp, you are sending a amplified signal through an amplifier, then off to your speakers. I'm hoping someone will chime in and say if this is bad or not for any part of the system. I didn't like it so that's why I spent half a day re-doing it all from the HU back.
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#5 Old 12-29-2011, 09:52 AM
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I know, stupid question but you always start with the basics... you did hook the blue/white wire in the harness to the blue/white wire on the head unit, correct? That's the signal wire to turn the amp on and off.

As for disconnecting the battery.. that's more to prevent a short than anything (I've done thousands without ever disconnecting it)

It *may* be a ground loop, but the way you said its thumping, to me, it makes it sound like a bad cap or circuit in either the jvc or the factory amp.

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#6 Old 12-29-2011, 12:25 PM
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Quote:
Originally Posted by rjr162 View Post
I know, stupid question but you always start with the basics... you did hook the blue/white wire in the harness to the blue/white wire on the head unit, correct? That's the signal wire to turn the amp on and off.

As for disconnecting the battery.. that's more to prevent a short than anything (I've done thousands without ever disconnecting it)

It *may* be a ground loop, but the way you said its thumping, to me, it makes it sound like a bad cap or circuit in either the jvc or the factory amp.

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Yeah, I was pretty careful about matching everything up right after I noticed that two of the colors didn't actually match up. I went off the diagrams and descriptions to make certain everything was going to the right spot.

I'm anxious to see if this does actually work. As I said, the thumping is gone, it's just a pop when the amp receives a signal now.
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#7 Old 12-29-2011, 12:42 PM
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If its popping when the system first turns on, and also maybe when it turns off (but not in between) then its most likely a timing issue. You can get turn on delay modules online for under $20, and what they do is delay the amp turning on a bit so the audio signal is already on. The pop usually happens when the amp is already on and *then* the audio feed kicks on

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#8 Old 12-29-2011, 01:56 PM
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Quote:
Originally Posted by rjr162 View Post
If its popping when the system first turns on, and also maybe when it turns off (but not in between) then its most likely a timing issue. You can get turn on delay modules online for under $20, and what they do is delay the amp turning on a bit so the audio signal is already on. The pop usually happens when the amp is already on and *then* the audio feed kicks on

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Cool, I'll keep that in mind if this doesn't work. It does happen when it's powered on and sometimes when it's powered off, but it also does it if I change the radio station (the brief time between signals when it is muted to avoid static between stations), when I change equalizer presets, that sort of thing, not just when the head unit is turned on and of. Hopefully this ground loop isolator will fix it, but if not, it could be worth checking a delay module.
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#9 Old 01-03-2012, 08:14 AM
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So the ground loop isolaters Crutchfield shipped out to me did the trick! Sound is perfectly clear without any extraneous noises when the ignition is shut off or when the amp turns on or off. It's a bit cramped behind the big double-DIN head unit with them in there, but hey, it works!
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#10 Old 01-03-2012, 08:16 AM
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good deal!

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