4 channel amp with one sub

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=40206
Printed Date: July 06, 2025 at 8:05 AM

Topic: 4 channel amp with one sub

Posted By: curt234
Subject: 4 channel amp with one sub
Date Posted: October 03, 2004 at 2:41 PM

Got a legacy 600 watt 4 channel sub. Was wondering if there was any way I got bridge both channels and run one sub to get max power???

Replies:

Posted By: jeffchilcott
Date Posted: October 03, 2004 at 3:05 PM

i am guessing you mean you got a legacy 4 channel amp and a sub not a 4 channel sub haha.. but no you can bridge a 4 channel amp to one sub unless it is a DVC and last i checked legacy didnt make a DVC sub. you will have to run it off 2 channels those you can bridge if you amp will run a 2 ohm mono load.....figureing this based on most legacy subs are 4 ohm, you need to let us know the model #'s and bridging capacity of your amp and what model sub

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

Posted By: kfr01
Date Posted: October 03, 2004 at 3:32 PM

Why would the amp need to be able to run 2-ohm mono to bridge 2 channels into a single 4ohm sub??? Wouldn't the amp simply see 4-ohms when bridged?

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New Project: 2003 Pathfinder

Posted By: jeffchilcott
Date Posted: October 03, 2004 at 5:34 PM

if it is bridged each side would see a 2 ohm load. some legacys wont even do a 2 ohm load bridged

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

Posted By: curt234
Date Posted: October 03, 2004 at 9:59 PM

The sub is a pioneer I tried bridgeing channel 1,2 and 3,4 but the sub don't work

Posted By: kfr01
Date Posted: October 03, 2004 at 10:25 PM

jeffchilcott wrote:

if it is bridged each side would see a 2 ohm load. some legacys wont even do a 2 ohm load bridged

I'm sorry, your statement is wrong.

"Some people say that when an amplifier is bridged onto a 4 ohm load, it 'sees' a 2 ohm load. While it is true that the same current flows whether the amp is bridged on a 4 ohm load or a 2 ohm stereo load, the amplifier is driving a 4 ohm load across its outputs. A single 4 ohm speaker can never be a 2 ohm load." https://www.bcae1.com/bridging.htm

I think you mean to say this: If the amplifier is 2 ohm stereo stable (stable with 2-ohms on either of the stereo channels), then it is 4 ohm bridgeable.

Almost no amps are 2-ohm stable in bridged mode.

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New Project: 2003 Pathfinder