Is my car sub woofer thumping noise caused by Bluetooth and/or USB 3.0 flash drive?

[Guest]

I have a question on a possible cause for my sub woofer making an occasional thumping sound. I have an Infinity Basslink sub woofer connected to a Kenwood KDC-X696 head unit. I listen to music with a 32 GB Sandisk USB 3.0 Flash Drive and have my Samsung Galaxy S5 connected to the head unit via Bluetooth for phone calls. I have looked at both the troubleshooting section of the manual for my sub woofer and the fuse in the sub woofer and ruled out the problem being with the sub woofer itself. I have even readjusted the settings on the sub. The changes appeared to solve the thumping problem, but then I noticed earlier today an occasional thump. The grounding seems to be secure as well. I suspect that it may be the RCA cable between the sub woofer and head unit going bad, but I have one question about another possible cause. When I am listening to my music off of my USB stick, my phone is connected to the head unit via Bluetooth. When I make or get a phone call, my head unit switches automatically over to bluetooth mode. I am aware that a USB 3.0 device can cause interference with Bluetooth connections, but can a Bluetooth signal also interfere with a USB 3.0 device? If so, could this be the cause for the sub woofer thumping noise. I am not picking up any thumping on my car speakers. Thanks in advance.

 

[steve1985]

recheck your ground. if your getting a thump noise from your subs like that its more than likely that your ground is not sufficient, making your amp unstable.
if you have a multimeter set it to ohms. take your multimeter and take 1 lead and run it from the NEGATIVE post on the battery and then take the other lead and hunt around for a spot that you want your ground location to be that reads somewhere close to ZERO ohms. once you find a sufficient spot. mark it and get some sand paper and scrape the ground location down to bare metal and use that spot for a ground. if you dont want to go drilling holes anywhere you can also check at bolts somewhere as well that already has a hole.

 

[steve1985]

the spot i have my ground location is something like .3 ohms for your reference.

 

[mymutter]

Do yourself a favor and move to a different grounding point on a completely different piece of sheet metal. I was always a fan of the seat mounting points. Pull the seat, sand down where the nearest bolt goes for a solid connection, crimp using the hammer crimper (NOT HAND CRIMPS), and then reinstall the seat running the bolt through the oring, then after tightening it, spray a light coat of primer or clear to keep the exposed metal from gathering moisture and rusting.

also, if the bolt is "painted" or "anodized" use a wire brush on it to get rid of the paint. if for some reason it's an aluminum bolt and is anodized, clean the bolt with oven cleaner (let it sit overnight and google how, it's an easy process to remove the coating). I always try to use a seat ground because it's one of the most secure bolting points on any car. After doing this you will know without a doubt it's not grounding.

 

[Apollonia]

okay, grounding is not your problem here. If it were, lets just say youd be writing about a different set of symptoms lol. going by what you wrote, it sounds as if you have an active sub (subwoofer w/ built in amp). That kinda helps remove alot of talk about wiring and impedance.
a very popular mistake ppl make with active subs is to send all the wiring "down the same pipe". all wires associated with power (the hot, remote turn on, antenna, etc) should NEVER come in contact with sound signal wiring (rca cables). a second popular mistake is insufficient power wiring. the kits sold with the subs most often get you into trouble (long story, another thread). be sure its at LEAST 8 ga AWG (and i cant stress AWG enough!) ... THEN make sure the GAIN on the amp is set to match the output of your head unit. .... add a ground loop isolator ( 2 rca male one end/ 2 rca female the other) on the cable BETWEEN the amp and head unit, and you should be all set.