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Subwoofer sounds horrible when cranked up


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I'm not a pro in this area so please be patient.

I recently had my sub installed at a shop in my area along with an amp and a lc7i.  Whenever I crank the volume up I get this

low rumbling sound from the sub.  It makes this noise even when there is no bass in the music I'm listening to (i.e. intro, outro).  However,

it doesn't make this noise while the music is paused.  When I looked in my trunk i noticed that they ran all of my signal cables with my power and ground, so I figure there's a ground issue.  I

went back to have it looked at and the guy told me that since my car is so small it will make that noise due to the amount of bass that I have, and if it was

in the trunk of a small car instead of the back of an suv I wouldn't hear it.  None of this sounds correct to me, am I correct in assuming that he was just being lazy?

I also noticed that my bass knob does not turn my amp all the way off.  When the knob is all the way down I can still hear my sub, just at a much lower volume.  Is this normal?

 

Oh yeah, due to my sub being a 2ohm and my amp not being 1ohm stable I am forced for now to operate at a 4ohm load.  This is only pushing 750 watts to a sub that 1100 watts is 

recommended for.  The instructions say that I can safely power it with 500-1200 watts rms.  Could this be a contributing factor?

 

  • 2009 BMW X3
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  • Audiocontrol LC7i

 

  • Kicker Comp Q 15
  • Kicker ZXS1500.1
  • Audiocontrol LC7i
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Yeah,  something is wrong. You wouldn't head it in trunk only because the backseat would muffle the noise, it would should be there. When you say your sub is a 2ohm, do you mean a dual voicecoil 2ohm, which is wired up to 4ohm?

 

Edit: how did the shop set your gain for the amp, what equipment did they use? Did they happen to tell you the Max Clean Volume that your headunit can be turned up to before you start to distort the signal? 

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I believe you are correct in assuming the installers are full of bologna. Signal wires should be nowhere near the power and ground imo. Start with moving your rca's to the other side of the vehicle or thereabouts. RCA,s might be faulty also. Don't worry bout the size of the vehicle or under powering your sub... That's not droid your looking for

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On 8/17/2017 at 8:13 PM, 3vil said:

Yeah,  something is wrong. You wouldn't head it in trunk only because the backseat would muffle the noise, it would should be there. When you say your sub is a 2ohm, do you mean a dual voicecoil 2ohm, which is wired up to 4ohm?

 

Edit: how did the shop set your gain for the amp, what equipment did they use? Did they happen to tell you the Max Clean Volume that your headunit can be turned up to before you start to distort the signal? 

Thats what I was thinking.  Yes, its a dvc 2ohm thats wired to 4ohm.  As far as the the amp goes, they set the gain at 12'oclock and the bass boost is 3/4 up.  They did not tell me any info about how high it could be turned up, only that the issue was the size of the car.  Thanks for your reply btw

 

  • Kicker Comp Q 15
  • Kicker ZXS1500.1
  • Audiocontrol LC7i
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23 hours ago, 8ten8 said:

I believe you are correct in assuming the installers are full of bologna. Signal wires should be nowhere near the power and ground imo. Start with moving your rca's to the other side of the vehicle or thereabouts. RCA,s might be faulty also. Don't worry bout the size of the vehicle or under powering your sub... That's not droid your looking for

Thanks I will definitely try that, I'm actually going to go back to the installer again this weekend.

  • Kicker Comp Q 15
  • Kicker ZXS1500.1
  • Audiocontrol LC7i
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Your gain is most likely set to high. There are tools that can help you set your gains properly. DD1 is one of those tools. Also your bass boost should be at 0. You are sending A distorted signal to subs which is not good for them.

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Did you buy this equipment from the shop? Wondering why they paired you up with a dual 2ohm sub on a mono amp only 2 ohm stable... 

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if you have a good pair of shielded RCA's you should be fine if the wires are ran together. There is another problem. I hate to say it but I think they gave you a bad sub. Check your ground. You could check to see if the signal wires is bad by getting a 3.5mm to RCA adapter and plug your phone or ipod straight to the amp. 

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I have seen a ground loop problem that caused a motor boat sound like what you are describing.  That was 25 years ago and I'm trying to remember how we fixed it.  lol

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