# Can I bridge my head unit?



## gjmallory (Apr 13, 2010)

Alright...I know what I am about to ask is TOTALLY ghetto...But...Can I bridge the "amp" in my Premier DEH-700BT to power my rear fill? I have an eclipse ea3422 amp - set to "two channel" for my comp set in the front.

A little bit more info: in a 2000 VW Cabrio - a convertible, so SQ is automatically compromised. The rear fill speakers are maybe 2 feet behind me. Headunit has 22 watts rms X 4.


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## gjmallory (Apr 13, 2010)

LOL! Wow. That was a dumb question! hahaha!


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## Sarthos (Oct 29, 2010)

Sure you can... maybe. If you bridge it into 8 ohms. Bridging into 4 ohms is a no-no


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## tanakasan (Sep 8, 2007)

Sarthos said:


> Sure you can... maybe. If you bridge it into 8 ohms. Bridging into 4 ohms is a no-no


Really!?! How?

OP asking about HU amp, not an external amp.

Robert


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## Sarthos (Oct 29, 2010)

Like I said, maybe. I know that running an two channel amp into 4 ohms bridged is pretty much the same as running each channel into 2 ohms. I would assume that running it into 8 ohms bridged would be similar to running the two channels into 4 ohms each.


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## Candisa (Sep 15, 2007)

The answer is simple: no.
The explination is quite simple too: because a headunit has to push quite a bit of power with the little current it is getting and with the limited space for an internal amp (note that some high-end amps don't even have a built-in amp), the internal amp is already bridged internally!
You cannot make a bridge between 2 channels that are already bridges.

Some old headunits do not use bridged speaker outputs, and are bridgeable with a little modification (inverting 1 channel per pair), but those headunits only give the amount of power on all 4 channels as a more modern headunit does on 2 channels.

Just use 2 channels to power the rear-speakers. Pushing double the amount of power to a speaker will only make it sound 3dB louder in theory. In the real world, 2dB is closer to the truth. This isn't worth frying a fine headunit since the profit is virtually nothing.

Isabelle


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## gjmallory (Apr 13, 2010)

Good point!...would be cheaper to buy an amp than fry a good HU!


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## tophatjimmy (Dec 16, 2005)

On that head unit, no you cannot bridge the rear channels, but Pioneer decks did offer this feature at one time. I had an old DEH-P630 that you could bridge the rear channels to a sub.

The DEH-700BT can run subs off the rear channels if you set the rear output to Sub W instead of full, but you cannot bridge the outputs.
http://www.pioneerelectronics.com/StaticFiles/Manuals/Car/DEH-P700BT_OperationManual0227.pdf Page 47.


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