# Bridge amp a 4-Channel Amp - Are Y-Adapaters Necessary?



## jooonnn (Jul 26, 2009)

This has really been bugging me a lot because I can't really find a straight forward answer!

My JL Audio G4500 is a 4 x 80W 4-channel amp.

Bridged it is 250x2 @ 4ohms

When bridging it to power two 4-ohm 6W3v3 subwoofers, is it necessary to use Y-Adapter Cables to fit all 4 rca inputs because they 1+2 and 3+4 are summed? I am just really confused when I did research on bridging but am I correct in saying that without a Y-Adapter, I am having reduced power and added distortion?


----------



## Notloudenuf (Sep 14, 2008)

It is not necessary. You only need 2 channels of input signal. I don't see how you could have increased distortion, I wouldn't worry about that too much.

Here it is from the manual

If you wish to send four discrete channels into
the G4500, simply use all four inputs (channels
1 & 2 and channels 3 & 4) and set the “CH 3&4
Input From” switch to “Discrete”.
If you wish to feed all four channels by using
only two channels of input, set the “CH 3&4
Input From” switch to “1&2” and use only the
inputs to channels 1 & 2.


----------



## jooonnn (Jul 26, 2009)

Ya that's what I thought but the manual also says 

"
Because a bridged pair of channels requires that 
both channels receive input, you need to 
connect both left and right inputs to the source 
unit. Connection of only one input will result in 
reduced power output, increased distortion and 
can cause the amplifier to overheat. 
Do not do this

"


What does that mean?


----------



## minbari (Mar 3, 2011)

when you bridge an amplifier you are summing the left and right channels into one channel. so it needs input from both the left and the right RCA to create this sound. what it is saying it, dont connect JUST the left OR the right RCA as this will cause only half the amplifier to work (in bridged mode)

long story short. connect inputs 1&2 and you are golden


----------



## jooonnn (Jul 26, 2009)

minbari said:


> when you bridge an amplifier you are summing the left and right channels into one channel. so it needs input from both the left and the right RCA to create this sound. what it is saying it, dont connect JUST the left OR the right RCA as this will cause only half the amplifier to work (in bridged mode)
> 
> long story short. connect inputs 1&2 and you are golden


Yes i understand that but 1+2 are summed inputs and so are 3+4, so connecting only 1+2 would leave me only left channel sound (mono). Right now I am connecting 1 and 3 (one for each summed pair) and it works in stereo but I am wondering if this is causing the amplifier to work harder since both pairs dont have an rca plugged in.


----------



## minbari (Mar 3, 2011)

if you have the little switch set to "1&2" then it internally routes signal to channel 3,4 and you dont need it.

by connecting 1 nad 3, you are actually doing exactly what they said not to do. DO NOT run it this way.


----------



## Notloudenuf (Sep 14, 2008)

minbari said:


> when you bridge an amplifier you are summing the left and right channels into one channel. so it needs input from both the left and the right RCA to create this sound. what it is saying it, dont connect JUST the left OR the right RCA as this will cause only half the amplifier to work (in bridged mode)
> 
> long story short. connect inputs 1&2 and you are golden





minbari said:


> if you have the little switch set to "1&2" then it internally routes signal to channel 3,4 and you dont need it.
> 
> by connecting 1 nad 3, you are actually doing exactly what they said not to do. DO NOT run it this way.


What he said. Hook up Left RCA into 1 and Right RCA into 2 (or vice versa) and set 3&4 to get signal from 1&2 

Hey Jon are going to the mini-meet in Wake Forest next weekend?


----------



## jooonnn (Jul 26, 2009)

Notloudenuf said:


> What he said. Hook up Left RCA into 1 and Right RCA into 2 (or vice versa) and set 3&4 to get signal from 1&2
> 
> Hey Jon are going to the mini-meet in Wake Forest next weekend?


I actually just tested it out and setting 3&4 to get signal from 1&2 just copies the summed mono signal. Channel 1 is still the same signal as Channel 2 (not stereo) so it looks like I'll need to pickup some Y-Adapters.


I'm actually not back in Clemson and am in Charleston right now, but either way its a 5 hour drive. I don't think I can afford that right now! 

I do have the ability to rent out a brand new nice pavillion and parking lot to host one here at Clemson though if you are interested!

The Villages at Town Creek - Amenities

Check it out!


----------



## minbari (Mar 3, 2011)

jooonnn said:


> I actually just tested it out and setting 3&4 to get signal from 1&2 just copies the summed mono signal. Channel 1 is still the same signal as Channel 2 (not stereo) so it looks like I'll need to pickup some Y-Adapters.


are you feeding the amplifier a stereo signal?
also in the manual it says that if you have the "bass boost" on then channel 3,4 are summed mono. make sure that is off.


----------



## duckymcse (Mar 15, 2009)

That's pretty much sum it up. I used the Y-adapter on my bridged JL 600/4 just for the piece of mind.



jooonnn said:


> "
> Because a bridged pair of channels requires that
> both channels receive input, you need to
> connect both left and right inputs to the source
> ...


----------



## minbari (Mar 3, 2011)

there is nothing wrong with it. but it is not nessecary. in fact if you set the switch to "1&2" the y-adpater did nothing


----------



## jooonnn (Jul 26, 2009)

Yea I just called JL and they said i should use Y-Adapters to let the amp run easier?


----------



## NRA4ever (Jul 19, 2010)

My old Phoenix Gold 475 just uses one set of inputs per channel to run mono. I'm running it that way now.


----------

