What is 'bridged' output?


Hi all,
Sorry to ask such a 'noob' question, but that is exactly what I am :)
I am putting together my very first car audio system and would like to learn to do it correctly.
first, can anyone point me to some good tutorials?
second, what the heck is bridged output? I gather it has something to do with the way you wire your speakers from the amp.
Any help would be GREATLY appreciated.

bridged output only pertains to multi-channel amps. it means combining the power of two channels into one. take for example; a 2 channel amp puts out 100 x 2 watts. each channel is receiving 100 watts respectively. by bridging the amp, you are combining channels to put out 200 watts to only 1 channel. hope this helps.

gojo, be sure to keep in mind the load on the amp. A speaker may present a 4-ohm load by itself but if you start wiring speakers together this number changes.

Same goes for amps. You'll notice that most amps are stable at 2-ohm stereo but only 4-ohm mono. If you bridge an amp from 2-channel down to 1-channel you have to make sure that the load on the amp is not too harsh for the amp's rating.

"can anyone point me to some good tutorials?"
Well, it's not that simple. You have pretty much all of the 12v world to consider in this biz so this tutorial you are hoping for comes in the form of an Electrical Engineering degree... Even the schools specifically for high-end installs (like the Installer Institute) assume you already know all the basics and most of the common advanced techniques. Buy magazines, read articles, study general electronic principals, break stuff...that's how we all get started.

Best luck!

Thank you both very much.
I am planning on bridging a Phoenix Gold amp (M-50) into one 8-ohm subwoofer. Should produce 250 watts mono to the sub. After much reading I have concluded that this will be safe for the amp, but will it perform ok with an 8-ohm speaker?
Now my question is am I defeating the purpose of bridging by only using one 8-ohm woofer? I really don't have the room for 2 woofers :(

Thanks again!

don't get an 8 ohm woofer if you're only going to use one. trust me, it will not pound. try to get a 4 ohm. i'll do some research on the amp and get back to you.

Output power per channel
Into 4ohm @ 12V DC - 50 WRMS
Into 2ohm @ 12V DC - 100 WRMS
Bridged power in to 4 ohm - 200 WRMS

These are the specs on your amp...if you want to run only one sub, make sure it's 4-ohm or you are cheating yourself out of half the amp's power. A solid, efficient 4-ohm 12" is perfect for this amp.

You're exactly correct Motoman22!
I have no idea where I got the 250 from.

I'm in a fix with the woofers, I have 2 of them (both 8 ohm) but only have enough airspace room for 1. They are Eclipse which I hear are pretty good.

Is it possible to convert the speaker to a 4 ohm load? Or should I just bite the bullet and buy a new speaker? Bummer is I'm low on funds and can't afford similar quality :(

if the 8 ohm sub has dual voice coils then you can wire it in parallel to cut it down to 4 ohms. if it's only single voiced, then there's no choice but to run it at 8 ohms.

Naw, I meant take it to a speaker shop and have it converted to a 4 ohm speaker. It's a moot point anyway I've already sold them and bought a 4 ohm speaker (not as good as the eclipse though :()

Thanks for all the help!

just curious...what speaker did you end up getting?

I got the Rockford Fosgate Punch RFP4410.
Not too bad but I'd like to have had those eclipse.

yeah. while the eclipse has way better sound quality, rockfords aren't too bad with spl. i'm sure you can set off a few car alarms and turn some heads. :)

I am planning to buy a JBL P80.4 amp and GT120 sub. I want to know whether i can bridge the output of 160x2 @ 4ohms to my sub woofer of 250 watts RMS. And how much power can I expect from the amp after bridging. And should the subwoofer be of only 4ohms coil as the bridged output of the amplifier is at 4 ohms. Is this amp sufficient to provide enough power for the sub of 1000 watts peak(250RMS) after bridging.
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