17 replies to this topic

[oliver122]

what it is is i have 2 speakers and the run of 2 channels , leaving me with 2 spare , i was wondering could you bridge them to give you more power , like you can do with an amp ? thanks in advance

[freshairmini]

Do you mean on the HU?

If so I do not think that is usually possible, as amps that can be bridgeable are designed to have that option, some aren't and i think if you try to bridge on an amp that isn't bridgeable then it damages it.

to be honest I've never heard of a HU that can have the speaker outputs bridged.

Have a look at the HU manual, if it is a feature it will tell you. If not don't try it.

[Ruckus]

I've not come across a head unit that does this.

I would not try unless it specifically state that the head unit does it and how to wire it in the manual.

[oliver122]

cheers guys , it was just a though is alll , thanks for the help

[shivi_d92]

as stated above not sure about your idea, if you want to increase the power though, you could try using a line driver which will change your standard HU output of say 4volts to around 9volts

[Ruckus]

as stated above not sure about your idea, if you want to increase the power though, you could try using a line driver which will change your standard HU output of say 4volts to around 9volts

He is not talking about the preamp output, he is talking about the built in amp output... Clearly?

[oliver122]

yea its directly out the back of the head unit , i had my dash out and see that i had 2/4 spare wires that come out the back of the plug (iso i think?) and wondered if you could join them together , was just a random thought is all :)

[shivi_d92]

as stated above not sure about your idea, if you want to increase the power though, you could try using a line driver which will change your standard HU output of say 4volts to around 9volts

He is not talking about the preamp output, he is talking about the built in amp output... Clearly?

ooops my mistake

[Pete93]

I bridged my headunit to power two 5inch subs before I got my amp, it worked really well as it meant that I could lower the resistance by wiring the subs in parallel.

[bluesprite]

my head unit has 4 outputs and I got the impression that the two left ones were just one output but split into two sockets to make it easier to wire in the extra speaker, and if that was the case then joining them together wouldn't achieve anything. the same would be true for the right too!

[Ruckus]

I bridged my headunit to power two 5inch subs before I got my amp, it worked really well as it meant that I could lower the resistance by wiring the subs in parallel.

my head unit has 4 outputs and I got the impression that the two left ones were just one output but split into two sockets to make it easier to wire in the extra speaker, and if that was the case then joining them together wouldn't achieve anything. the same would be true for the right too!

Sorry guys but I'm not sure where to start here!!

Where do you guys get this 'information'!! Looks like dangerous guess work!

Ok for a start when you bridge an amp (any amp even the baby one in a head unit) you effectively half the load (lower means HARDER to handle). So your 4 ohm sub will appear to the bridged amp as a 2 ohm load...

If you then wire a pair of 4ohm speaker in parallel you will be presenting the Bridged amp a 1 ohm load!!
The amp will pull loads more current and create loads more power until it goes bang! Unless its designed to handle low loads... Which headunits are not!


And no the 4 outputs on a headunit are not 2 channels split.
They are 2 channels for the front and 2 for the rear.
They will all have separate internal circuitry and in 99% of headunit I've seen they are not designed to be bridged or to handle loads down 1 or even 2 ohms.

Just because it worked for you does not mean its the correct thing to do. Remember this is a technical sub-forum, people may well act off 'advice' they read on here... It's best if it's technically right don't you think?

Edited by Ruckus, 27 January 2012 - 06:41 PM.

[TA2DMAC]

What head unit and what speakers. Sounds like you have a 4 channel head unit which as previously described gives you 2 front input and 2 rear. Know your head unit will let you know what ohm load it can handle. Most are 4ohm. Very few are bridgable to 2ohm, which is what you are looking to do. Yes it is possible to do, but it can and the eventually will fry your head unit if it is can't handle it. Plus the gain in a head unit will be very minimal. Most head units run 4 channels at 20watts peak, about 10-12rms. Bridging will give you possibly 35watts out of the two channels and about 15watts rms. So isir worh risking 3-5 extra watts to possilby fry your system?

[Pete93]

I bridged my headunit to power two 5inch subs before I got my amp, it worked really well as it meant that I could lower the resistance by wiring the subs in parallel.

my head unit has 4 outputs and I got the impression that the two left ones were just one output but split into two sockets to make it easier to wire in the extra speaker, and if that was the case then joining them together wouldn't achieve anything. the same would be true for the right too!

Sorry guys but I'm not sure where to start here!!

Where do you guys get this 'information'!! Looks like dangerous guess work!

Ok for a start when you bridge an amp (any amp even the baby one in a head unit) you effectively half the load (lower means HARDER to handle). So your 4 ohm sub will appear to the bridged amp as a 2 ohm load...

If you then wire a pair of 4ohm speaker in parallel you will be presenting the Bridged amp a 1 ohm load!!
The amp will pull loads more current and create loads more power until it goes bang! Unless its designed to handle low loads... Which headunits are not!


And no the 4 outputs on a headunit are not 2 channels split.
They are 2 channels for the front and 2 for the rear.
They will all have separate internal circuitry and in 99% of headunit I've seen they are not designed to be bridged or to handle loads down 1 or even 2 ohms.

Just because it worked for you does not mean its the correct thing to do. Remember this is a technical sub-forum, people may well act off 'advice' they read on here... It's best if it's technically right don't you think?

I completely agree with you saying that it's best that the advice should be technically correct. However all I said that it worked well for me, although I should have pointed out that each sub had an 8ohm resistance and that I only bridged it on the rear speaker outputs.

Even if it's technically incorrect my headunit didn't once over heat but that's not to say that yours won't.

[Ruckus]

Yeah sorry, I was at the end of a bad day.

But you would not belive the amount of owners I've helped over the years, that have done or are doing damage to thier hard earn't kit due to a throw away comment on the internet. That's has been takened as gospel and acted on! :/

[Pete93]

No problem