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Pulsing sub? Weird freqencies?

Old 06-05-2009, 08:17 PM
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Pulsing sub? Weird freqencies?

Okay, this is a pretty specific problem, I'm hoping someone can help me.

I have a Scosche 550w amp powering an old school Memphis 12.

Since I could not get a remote wire to work on my headunit (a new Pioneer), I wired it directly to my fuse and put a switch in the line to turn it and off when I want, since it doesn't get a signal from the head unit.

This is my problem:

-If I turn the remote switch on, then turn my car on, before any music comes on, the sub pulses and makes weird radio-frequency noises. It does this until music comes on, and then at that point it acts normal, playing normal bass.

-If I turn my car on and already have music playing, and then turn the remote signal on, it doesn't make the weird frequencies or pulsing and just acts normal, playing bass as it should. Although, one time it started to pulse and make frequencies while I had been driving just down my road.

Details:

-I never noticed it doing this before (although I don't think I would have), but when I turn the switch on for the remote, the amp light for it being under powered lights up for a second, and then goes out as the regular power light comes on.

-It doesn't pulse if I don't have the RCA's connected. I don't know why. I've already ran another set of RCAs from my headunit to the amp to test if that was the problem, but it pulsed even with a brand new set of RCAs just running over my seats with nowhere to ground to.

-Also, when it pulses, the interior light in my car dims and lights back up as the sub pulses.


Can anyone give me any tips for this? I appreciate any help a lot!

Last edited by MHarrisEP; 06-05-2009 at 08:26 PM.
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Old 06-05-2009, 08:59 PM
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Addition:

I tried it with another amp, with the same or similar results.

With this amp (Rockford Fosgate 200w), I get the same results only when playing with music it doesn't play the bass in the song, but random bass.

The other amp may have been doing this and I didn't notice.


Also, my power cable is run on the left side of the car while the remote and RCA's are run on the right.
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Old 06-05-2009, 10:05 PM
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dude, fix yours ground wires..amp to frame.....battery to frame.....engine to frame,
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Old 06-06-2009, 10:44 AM
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Like bart suggested, it sounds like a ground issue. That's where I'd start looking.
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Old 06-06-2009, 01:46 PM
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Well. I ran a new power wire. Re-did my ground. And I'm still having the issue. I have my amp grounded to a nut and bolt behind a panel in my trunk. It's been like that for nearly a year. Any reason why it'd be acting up now?
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Old 06-07-2009, 03:35 AM
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corrosion.... you should try moving the ground to a new location, and check to ground on your head unit too, it could be using your rca's to ground through as well
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Old 06-07-2009, 10:46 AM
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I tried grounding it to 2 new places and got the same results.

I also checked that the ground wire was still connected behind the headunit and all that. Although, I don't know where the wire actually goes.

And, I've tried different sets of RCAs, so I'm fairly sure it's not grounding through them.

any other ideas?
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Old 06-07-2009, 09:52 PM
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I have a pioneer deck as well and ran in to similar problems with my speakers and subwoofer. Along with the wierd subwoofer sounds was some alternator whine. Pioneer has a problem with the internal fuses blowing for the rca's which often cause these problems.

Try wrapping each of your rca cables where they connect to the rear of your deck with speaker wire. Take the other end and find a screw on the deck to attach it to. Effectively you are grounding the rca cables. I tried everything with new power and ground and this resolved it right away.

see the following forum for pics. (btw I didn't know if I was allowed to link to others forums so I apologize in advance)

>>>Engine whine and ground loop fixes... take two - Car Audio Forum - CarAudio.com
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Old 06-07-2009, 10:43 PM
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Wow, thanks! That worked perfect. I can't thank you enough, I was lost!
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Old 06-07-2009, 10:46 PM
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Originally Posted by MHarrisEP View Post
Wow, thanks! That worked perfect. I can't thank you enough, I was lost!
No problem, I searched for quite few hours to find that fix. Now just send cheque or money order to me in the amount of $200. (1 hour pay x 2 for days off).
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