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Thread: Bridging HU amp?

  1. #1
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    Bridging HU amp?

    This may be a dumb question, but...

    If I'm running my rear speakers off an external amp, can I bridge the head unit amp to increase the power to the frint speaker? Is it something as simple as connecting the (-) of the front left lead to the (+) of the rear right lead then connecting the (-) of the right rear lead and the (+) of the front left lead to the speaker?

  2. #2
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    well if you don't care about the ability to have fading (forward/back) and just stick with stereo then I think that you can just put the front speakers in parallel with the rear amp (i.e. but both '+' to the '+' on the speaker and both '-' to the '-' on the speaker). However if the 2 signals are even slightly out of sync then it might really screw up your speakers.

    Honestly I wouldn't bother doing that. What HU do you have and what speakers do you have and what amp? You'll prolly blow your speakers trying to do that
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  3. #3
    Raw Wave Rob Withey's Avatar
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    You'll get little benefit from doing that, you'll just stress (and possibly blow) the output amp on your head unit. Bridging is not putting in parallel (but then you knew that, right?).

    Assuming the amps are not bridge amps to start with, what you need to do is get the rear speaker signal in anti-phase to the front speakers. Then use the + signal of left front and the + signal of left rear and use these to drive your left speaker. Same with the right. That's the basics of a bridge configuration. If the amps are already bridge config, you'll see no benefit though, since you've thrown away half your voltage swing by ditching the -ve line on each amp (which on a bridge amp is not ground).


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  4. #4
    C4M
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    I'd go with Rob's answer.

    Head units are often already bridged - thereby enabling them to make outlandish claims as to the output.

    Bridging them again would be Very Bad.

    Oh - I'd be running the front speakers of the amp - not the rears (unless the rears happen to be subs - you didn't say). When you go to a concert, do you face the stage or the back

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  5. #5
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    I (obviously) know little on the subject but I figured running the rears off the amp would be better because they're 6x9 and would reproduce a wider frequency range than the front 3.5's. Right?

    BTW, the HU is a Blaupunkt X-Line CD41, the amp is a Jensen 600W 4-channel. I will have a sub in the trunk.

  6. #6
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    Anyone have a comment on this? Should I amp the fronts or the rears? Why/why not?

    Thanks!

  7. #7
    FLAC
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    firstly (and expecting flames from this) 6x9's are EVIL,EVIL speakers!!!! speakers are meant to be round, not ovals!!! I would never, ever dream of going back to 6x9's - they are only designed for getting bass from speakers that go into tight parcel shelfs,etc......

    if you want bass, and propper bass, you need to get a sub - no two ways about it... I have seen cars with 4 * 6x9's on their rear shelf - you can really spot the morons, cause with the money they spent they could have got a nice little 10inch sub and a few 5-6inch component speakers and have a much better system...

    personally, ditch the 3.5" speakers up front, get some decent 5-6inch coaxials/splits for the front doors/kicks.... amplify them with 2 of the four Jensen channels.... chuck the 3.5inch speakers in the rear parcel shelf running off the Blaupunkt head unit for some 'rear fill' and bridge the remaining two Jensen channels into 1 for the sub woofer...... and of course set your crossover points so that your sub gets less than 80-160Hz freqs and the fronts get greater than 80-160Hz...

    and, never, never, never bridge a headunit. Do not pass go, do not collect $200!
    Project - GAME OVER :(

  8. #8
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    Hmmm... a nice idea, but I don't have the money for that, neither do I want to cut holes in my car. I have the 6x9's, I have the 3.5's, so they're going in. I also have a 10" sub which is going in (as stated in the post). I'll be cutting the bass to the 6x9's (which are 4-way coaxials) so their main purpose is mid-high range. The 3.5's are 2-way Rockford Fosgates which I think will sound much better than 6" in the doors (which I had before in my Escort). So, given that information, would you run the 3.5's or the 6x9's off the amp?

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