Bridging 4 Channel Amp for Front Components

[ktennies]

Like the title says, I'll be bridging my four channel amp into two channels to run my front components so I can get max power from the amp. The components have passive crossovers. There will be no rear fill.

I've been reading online to understand how to run RCA cables to accomplish this while remaining in stereo.

The most popular answer I see online is to only run the front RCAs and buy two Y-splitter cables and run the two left channels into the front left and right (so amp front = left) and run the two right channels into the rear left and right (so amp rear = right). The rear RCA outputs on the head unit would go unused. This is easy enough to understand.

Questions:

1) If one had an extra RCA cable, would the outcome be different from the above answer if both front and rear RCAs were run from the head unit with the two left channels going into the front left and right (so amp front = left) and run the two right channels into the rear left and right (so amp rear = right)? I mean it would be the same difference because the head unit has already doubled the channels (y-split the channels) itself for front and rear, right?

2) Wouldn't using both front and rear preamp outputs result in increased voltage to the amp, or does a head unit's stated amp voltage refer to total preamp voltage of all preap outputs combined?

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[bbeljefe]

I haven't tested these arrangements in the same system so I can only speculate. But I would bet that if there is a difference, it won't be audible.

 

[d77543020 10+ year member]

I'm doing this now but it really depends on the amp jbl amps for example when iI bridge I still get left and right but some amps when you bridge it automatically goes to mono

 

[DARKHART 10+ year member]

Not sure which amp you are using but most decent 4channel amps should have a "bridged" switch that once engaged should allow you to use only one set of rca inputs thus eliminating the need to run a set of Y's and as far as the output of the deck goes if it has say 3 sets of 4volt outputs, that means that each (left and right) rca lead has the capability of outputting up to 4volts cleanly before or up to clipping. They don't combine into a higher voltage. Hope this helps.....

 

[ktennies]

I'm doing this now but it really depends on the amp jbl amps for example when iI bridge I still get left and right but some amps when you bridge it automatically goes to mono

Not sure which amp you are using but most decent 4channel amps should have a "bridged" switch that once engaged should allow you to use only one set of rca inputs thus eliminating the need to run a set of Y's and as far as the output of the deck goes if it has say 3 sets of 4volt outputs, that means that each (left and right) rca lead has the capability of outputting up to 4volts cleanly before or up to clipping. They don't combine into a higher voltage. Hope this helps.....

The speaker amp is a JBL GT5-A604. There is no bridge switch. I'm just going to use y-splitters with an RCA cable from the front outputs on the head unit and leave the rear output alone. I'll send both (front) left signals to the front RCA inputs on the amp and both (front) right signals to the rear RCA inputs on the amp. The left components will go to the amp's front outputs bridged and the rights will go to the rear outputs bridged. I was thinking this might result in preamp sound quality loss of four volts down to two volts from the head unit, but I'm reading that the y-splitters are creating a parallel circuit and will not result in voltage loss except miniscule amounts.

One more question:

Since I'm only going to be running preamp input from the head unit's front and subwoofer preamps (to different amp for subs) with the rear preamps being unused, should I adjust the head unit's fader all the way to the front before setting the gains on my amps?

 

[Side Show 10+ year member]

don't think it'll make any difference about the fade.