Subwoofer rumbles when changing CD tracks

SSTJ

SSTJ

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Not really a TJ-specific topic, but you all are my go-to for all questions about my TJ.

When I turn on my stereo, and also when I change tracks on a CD, and also when I scroll through various EQ settings, my subwoofer rumbles. It's a quick series of muffled, shuffling sounds. Lasts less than a second. Does not happen if I turn down the volume and then change tracks. With volume back on, it is louder or softer depending upon the remote "punch" setting for the sub.

Also, if I am playing a CD and then pause the CD (but it is still spinning), I get a soft, constant flutter, about one or two two taps per second, I'd say. Also, when I turn on my dome light, I get one gentle, muffled "thump".

The power and signal cables for the sub are zip-tied right up against the wires to my overhead speakers and dome light. Is that my problem? Head unit is a Sony MEX-N5300BT. Subwoofer is a Rockford Fosgate PS-8.

Any ideas? Update: In the comments below, I have confirmed that I have a good ground for the amplifier, and also for the head unit.
 
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You might place a good size electrolytic (polarized) filter capacitor across the - and + power leads powering the subwoofer amplifier. And make sure the amplifier is properly grounded. Also, undersized power leads can make it more susceptible to noise.
 
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Jerry Bransford said:
You might place a good size electrolytic (polarized) filter capacitor across the - and + power leads powering the subwoofer amplifier. And make sure the amplifier is properly grounded. Also, undersized power leads can make it more susceptible to noise.
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Thanks Jerry. I can try that. Also, I'll update the OP with this tidbit, which I just discovered:

Also, when I turn on my dome light, I get one gentle, muffled "thump".

Does that change your advice in any way?
 
No, I'd expect it to help with that issue too. Do first check the gauge of power cables and the ground connection quality.
 
Jerry Bransford said:
No, I'd expect it to help with that issue too. Do first check the gauge of power cables and the ground connection quality.
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Thanks Jerry. Ok, I'll check that first. Also, just update the OP with a little more detail that I just discovered, about volume levels.

Will report back after checking wires and grounding.
 
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Jerry Bransford said:
No, I'd expect it to help with that issue too. Do first check the gauge of power cables and the ground connection quality.
Click to expand...

Hi @Jerry Bransford. Thanks again. I can confirm that the + and - cables for the amplifier are 8 AWG. Positive runs straight to the battery, and negative runs about 15" to a clean-metal connection to the tub. The positive wire, the smaller "remote on" wire, and the RCA wires are all bundled together along the full length of the rocker panel.

I also updated the OP with a few more details that I discovered while tinkering this evening. The spinning CD thing really surprised me.
 
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Jerry Bransford said:
Your power wiring is more than adequate!
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Ha, yes, it's left over from a previous, larger amplifier.

So, do you still think that the capacitor is the way to go? If so, do you have any advice on specs, brand, etc? I can Google of course, but I imagine I'd quickly get lost in details I don't yet understand.
 
pagrey said:
It sounds like your Sony deck is the problem. I don't mean to suggest Sony is bad or anything, that's just what appears to be the issue.
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Hey, thanks. I was wondering the same, especially after the spinning CD thing. I also found a post on another forum in which someone suggested that the head unit could be the culprit. I might call Crutchfield and see if they've heard of this happening with any of their units.
 
Spoke with Crutchfield, where I bought the head unit. Their recommendation is to check the grounding on the head unit itself, in case an improved ground connection could give the CD player's noise/interference a better place to go. Will do that soon.
 
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I'd say it could be a few things, but I would un-ziptie the signal wire tied to the power wire could cause interference, and then when you throw in the dome light wiring touching...I think it would be that. Try separating the wires and potentially using a wire sleeve. This site will give you ideas for a sleeve.

https://www.techflex.com/
Could also be a bad head unit. @Jerry Bransford mentioned a capacitor, which helps tremendously in the proper situation, but how about your battery, what kind of shape is it in? How old is it? Can you check the voltage?

I would check voltage and then try separating the wires and using a sleeve.

Good luck!!!
 
skrelnik said:
I'd say it could be a few things, but I would un-ziptie the signal wire tied to the power wire could cause interference, and then when you throw in the dome light wiring touching...I think it would be that. Try separating the wires and potentially using a wire sleeve. This site will give you ideas for a sleeve.

https://www.techflex.com/
Could also be a bad head unit. @Jerry Bransford mentioned a capacitor, which helps tremendously in the proper situation, but how about your battery, what kind of shape is it in? How old is it? Can you check the voltage?

I would check voltage and then try separating the wires and using a sleeve.

Good luck!!!
Click to expand...

Hey, thanks very much.

Head unit has a meter on it, and it reads 11.8V when turned on without the engine running, and 14V immediately after starting the engine. It's relatively cold here right now (40s and 50s), and I haven't run the Jeep in 24 hours.

As for the sleeve, I like that idea, but I don't understand it yet. When the subwoofer is turned down, I don't hear any of these sounds. So it doesn't seem like the sounds are getting into my speaker wires in the first place, to cause interference in my subwoofer wires. Or am I misunderstanding how you think these co-bundled wires are messing with each other?
 
SSTJ said:
Ha, yes, it's left over from a previous, larger amplifier.

So, do you still think that the capacitor is the way to go? If so, do you have any advice on specs, brand, etc? I can Google of course, but I imagine I'd quickly get lost in details I don't yet understand.
Click to expand...
Jerry Bransford said:
Your power wiring is more than adequate!
Click to expand...
Any ideal on capacitor to recommend
 
Just for reference, I recently installed a new amp & a powered sub in our '03, to go along with the upgraded head unit that I installed about 6 months ago.
I now have a significant buzz in the speakers that I had not heard previously (likely excluding the radio as the source).
My experience (along with a bit of recent research) suggests that I have a ground loop, and/or ignition noise from the alternator.
I have a relay that turns on the hot wire for the amp & sub with the ignition, (as well as the trigger wire from from the radio).
My ground wires are connected under the center console, but likely has a different potential compared to grounding directly at the battery. This difference in potential is what is known as the ground loop, which can cause noise on the power wire & cause a static hum or buzz through the speakers.

My plan is to install noise suppression on the power wire, along with routing a new ground wire for the amp & sub directly to the battery.
 
My sub wolfer will randomly thump / static sound after reading this post noticed it would do this with slight incoming voltage changes So was thinking cap might help
It was also doing this with my old head unit and now new one
 
Davidtj said:
Any ideal on capacitor to recommend
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I'd probably try a 50v 250uf electrolytic. That type is polarized so make sure you connect it that way. Yes it's only a 12v circuit but potential noise spikes will be higher voltage.

Also are any of the components set to auto select the inputs? If so I'd change that and set it manually to the correct type of input.
 
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