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line level converter diy?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=128215
Printed Date: June 29, 2025 at 10:42 PM


Topic: line level converter diy?

Posted By: big_bumps
Subject: line level converter diy?
Date Posted: August 11, 2011 at 5:59 PM

I'm looking to hookup an amp for my subwoofer to the factory head unit in my car. My amp doesn't have speaker level inputs. The line-level adapters seem to be pretty simple. Could one be built with just a few resistors in a voltage divider circuit or would this affect the the speakers that it would be parallel to?

Thanks

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"It hit so hard for a week.."



Replies:

Posted By: DYohn
Date Posted: August 11, 2011 at 7:53 PM
They are really inexpensive and probably cost less and are more reliable than a DIY solution would be.

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Posted By: big_bumps
Date Posted: August 11, 2011 at 8:43 PM
They wanted $49 at the local car audio place. I'm sure that's a rip off tho..

Any suggestions on a good brand? I just need the basics, don't need level controls or anything my amp has variable line-in but only up to 6V.

Thanks

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"It hit so hard for a week.."




Posted By: itsyuk
Date Posted: August 11, 2011 at 8:49 PM

read your manual closely and you may find that speaker wires can hook directly into the 6v capable input without an adapter. many amps can do this.

what amp is it?



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yuk
quiet rural missouri, near KC.
If your system moves you physically and not emotionally, you have wasted your money.




Posted By: big_bumps
Date Posted: August 11, 2011 at 9:09 PM
It's a JBL GTO7001



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"It hit so hard for a week.."




Posted By: i am an idiot
Date Posted: August 11, 2011 at 9:11 PM

If you do find the info in the manual, and you insist on using this, please take the following precautions.  Cut an RCA cable in half.  Strip both the left and right wires of the cable.  Each cable will have a shield around a center conductor.  Separate the shield and the center conductor.  Twist the 2 shield connections together and ground them to the chassis of the vehicle.  Connect only the positive wire of your radio to the center conductor of the RCA cable.  Do not connect the radio's negative speaker wire to anything.  The only connections of the radio are going to be the left and right positive speaker wires.

Most amplifiers have a common shield ground between the left and right RCA cables.  Some manuals ignore this.  If you connect the radio's negative speaker wires to the shield of most amps, there will be problems.  The safest way to do it is just connect the positive wires and ground the shield of both inputs of the amp.  Do not connect the radio's negative speaker wires to anything related to this amp.





Posted By: itsyuk
Date Posted: August 11, 2011 at 9:18 PM

I have wired speaker wires to rca plugs and plugged them directly into mostly JL, mtx and kicker amps with no problems.

each brand has its own recommendation.



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yuk
quiet rural missouri, near KC.
If your system moves you physically and not emotionally, you have wasted your money.




Posted By: itsyuk
Date Posted: August 11, 2011 at 9:23 PM

i agree. positives only is the best way.

i just tap a wire fron the pos speaker wire and solder it to the pin on a new rca plug and plug it in. one for each channel.

i havent done this with any JBL amps.



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yuk
quiet rural missouri, near KC.
If your system moves you physically and not emotionally, you have wasted your money.




Posted By: DYohn
Date Posted: August 12, 2011 at 10:55 AM

big_bumps wrote:

They wanted $49 at the local car audio place. I'm sure that's a rip off tho..

Any suggestions on a good brand? I just need the basics, don't need level controls or anything my amp has variable line-in but only up to 6V.

Thanks

Try this.



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