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1-8ohm wiring help for 4 ch/amp

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=24356
Printed Date: June 10, 2024 at 12:33 PM


Topic: 1-8ohm wiring help for 4 ch/amp

Posted By: scriv1969
Subject: 1-8ohm wiring help for 4 ch/amp
Date Posted: January 11, 2004 at 12:48 AM

If anyone can help me, i should be in the right place. Here is what I have.Alpine Head unit, US acoustics USB-4085 85 x 4 Car Amp rated at 120x4 (2ohms). Bridged power 240x2. minimum impedance bridged is 4 ohms, 1-JL Audio 10" (8ohm),pair of Jbl 6.5" coaxials(4ohm each). I want to get the most power out of my amp (hopefully Bridged). And sub. I am very tight on space in the vehicle Im in so 2 subs is out of the question,and money is tight. My ??? is with the 8 ohm sub I probably should bridge 2 channels of the amp (left + and right -) will the amp see 8 ohm load 0r 4 ohm load, & what kind of power will I be gettin with the 8 ohm sub. Better idea If you guys had this system with same limitations how would you set up. Thanks in advance if somone could help me out



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Rod



Replies:

Posted By: eargasm
Date Posted: January 11, 2004 at 5:21 AM

basically, if you bridge your 8ohm sub across 2 channels of the amp, the amp will see a 4ohm load.

someone else can answer how much power, i cant remember how. but dont worry. it will only be a 3dB difference anyway. whether it's 120ohm or 240ohm.



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2001 Ford Fairmont
Alpine DVD, screen,
5.1surround processor,
5ch Class-T amp, TV tuner
and centre channel.
Focal 3way Utopia splits.
VDO navigation. Stinger cap.
Soundstream Exact subs.




Posted By: mark241
Date Posted: January 11, 2004 at 10:09 AM
IF you bridge the amp over the two channels and the sub is 8 ohms, you'll only get half the output power that you would at 4 ohms, so 120 watts.




Posted By: DYohn
Date Posted: January 11, 2004 at 10:22 AM
That US acoustics amp is a very nice choice.  Bridging an 8-ohm sub onto two channels will give each amplifier channel a 4-ohm load and the amp will deliver 120 watts RMS into the bridged load.  The 240X2 rating is at 4 ohms total, or 2 ohms per channel.  Connect your coaxials to the other two channels and the amp will deliver 85 watts RMS per side.  This should result in a nicely balanced setup.




Posted By: scriv1969
Date Posted: January 11, 2004 at 2:57 PM
Hey Guys appreciate the help, so many configurations can get kinda confusing.

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Rod





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