# channel bridge?



## altimobile (Jan 9, 2004)

Hey howzit audiophiles. I just had a system in stalled in my 2004 Alty. Kenwood cd player with the stock speakers in the front doors, 6x9 250w Kenwoods in the rear deck and some old Rockford Fosgate 8s in boxes in the trunk. I have a Lightning Audio Bolt amp <---- I know, (junk) It's a four channel. 75wx4. its running the 6x9s and the trunk speakers. What I'm going to do is get rid of the Fosgates and bridge the back two channels for 150w going into a new 12" sub. How exactly do I go about doing this "bridge" ? sorry if this is a dumb question. Oh, also it has open rca jacks for output that I can supposedly "daisy chain" another amp? would I be able to hook up the power, remote line, and ground, from the second amp to the lightning amp also? thanks.


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## ny98max (May 10, 2003)

This has disaster written all over it...


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## Punkrocka436 (Jul 8, 2003)

well....


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## Punkrocka436 (Jul 8, 2003)

ny98max said:


> This has disaster written all over it...


 well....

1. To bridge your amp, look at the audio outputs and see if there is some writing that says "bridge channels", normally you take the positive output from one channel, and the negative output from another and use both channels to give more power to the speakers

2. You cant "daisy chain" the rca cables. There are two input jacks, one for the front stage, and one for the rear stage.

3. Buy a distribution block and feed 4 gauge into the distribution block, and 2 8 gauge FUSED output wires and send those to the amps

4. For the remote turn on, you need a 30 amp automotive relay(radio shack has them for like 4 dollars). Power the relay through the distribution block with a fused 14 gauge wire. Ground it to somewhere on the chassis with 14 gauge as well. The remote turn on lead goes in the input terminal, and use a wire to a barrier strip from the output. Route 2 wires from the barrier strip to the amps

Please please please PLEASE be careful doing this


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## sr20dem0n (Mar 19, 2003)

Punkrocka436 said:


> well....
> 
> 1. To bridge your amp, look at the audio outputs and see if there is some writing that says "bridge channels", normally you take the positive output from one channel, and the negative output from another and use both channels to give more power to the speakers
> 
> ...


1 - right, make sure that your sub is 4ohm though or you're most likely fry your amp
2 - yes you can daisy chain rca cables, as long as the first amp has rca outputs (many do)
3 - no need for a fused distro block if you're just doing 1 4->2 8's, you can get one if you like but IMO it's overkill. Just go for a normal distro
4 - no need for a relay if it's only 2 amps, just run a short wire from the remote input on one amp to the remote input on the other.


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## Punkrocka436 (Jul 8, 2003)

im still say get the fused distro, just for peace of mind if some freak accident did happen, the fuse would blow instead of melting the wire


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## sr20dem0n (Mar 19, 2003)

but that's what the main fuse by the batt is for

I just don't see the use for a fused distro unless your main power wire fuse rating greatly excedes the ability of the smallest wire in your system. Unless you're running 0/1 to the distro and then 8 to your amps, I don't see this happening.


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## vrmchh3z (Jan 20, 2004)

even though we argue about sub choice i have to agree wid you on this one


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## altimobile (Jan 9, 2004)

OK< the first amp is a four channel and it is wired to the battery with 8 gauge with a fuse at the battery. it has open rca jacks that the manual says can be used to daisy chain another amp. the second amp I want to use is a two channel 150 watt rockford fosgate. can I just plug the rca cables(L R) from the first amp right into it and hook wires directly to it from the first amp for power and ground? using the same gauge? basicaly I'm wondering if I can hook the power and ground wires for the second amp direcly to the first amp. will it rob any power from the first amp or does it have to be wired separate or to a distributer board or something? whew! thanks


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## sr20dem0n (Mar 19, 2003)

well, if you had used 4ga to your first amp you could split it to both, but I doubt 8ga will be effective enough. The problem with using a single 8ga run for both amps is that it has too much resistance, so when both amps are sucking all this current, it'll cause a voltage drop. So say you have 14V at your battery, you might only have 12.5 or 13V at your amps because of the voltage drop across the wire, and this means less power going to your speakers.

I would run a new power wire, you could do another 8ga and it would be fine, but if you plan on upgrading in the future you should probably run 4ga for your new amp to give you some headroom later on.

Sorry Punkrocka436, I was drunk and in an argumentative mood last night, hehe. It's normally wiser to use a fused distro. Sometimes it can be a bit overkill, but when you're dealing with the high-current electrical runs in a car, overkill is always a good thing.


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## vrmchh3z (Jan 20, 2004)

yeah it would be better to run the 4 gaug cus if you think about it in turms of a staw if you have to small diamiter straws and ur trying to drink with them it would be alot easier to drink from one straw twice the size as the small one rather than two of the smaller straws and this is the same way ur amp feels because even though two 8 gaug may seem the same as one four mathmatically there is more resistance with 2 8's rather than one 4


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## sr20dem0n (Mar 19, 2003)

vrmchh3z said:


> yeah it would be better to run the 4 gaug cus if you think about it in turms of a staw if you have to small diamiter straws and ur trying to drink with them it would be alot easier to drink from one straw twice the size as the small one rather than two of the smaller straws and this is the same way ur amp feels because even though two 8 gaug may seem the same as one four mathmatically there is more resistance with 2 8's rather than one 4


actually there's more resistance with 1 4 than with 2 8's


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