So you paralleled the amp outputs together to get double the drive current? i.e. you joined FR+ and RF+ together and made that the R+ for your speaker etc?

In that case if you don't have exactly the same signal coming out of FR+ and RR+ then the two amps will be fighting against each other just dumping current into each other and getting hot for no purpose. So it seems to me you would be wise just to use one left input and one right input so there's no difference between front and rear on each channel and of course don't use the F-R fade control. The L-R pan control should still work.

 

First things first, if you want to run a four channel amp as a two channel amp then you only want two inputs, preferably RCA inputs. If you must use speaker level inputs then just use one pair (either front or back, and then fade the head unit appropriately). Is your four channel amp definitely bridgeable? If you're really not sure how to wire it up then post pictures of the inputs and outputs and someone on here will tell you how to do it.

 

First things first, if you want to run a four channel amp as a two channel amp then you only want two inputs, preferably RCA inputs. If you must use speaker level inputs then just use one pair (either front or back, and then fade the head unit appropriately). Is your four channel amp definitely bridgeable? If you're really not sure how to wire it up then post pictures of the inputs and outputs and someone on here will tell you how to do it.

Ah.. That's the answer I'm looking for.
Doh, I linked the front and rear speaker level inputs together assuming it will give stereo. So now that I've connected all 4 connections on speaker level input is this mono then?

Yes the amp is bridgeable.

 

Not exactly. What you've done is to confuse and upset the head unit by joining the front and rear outputs together - see Martins post above. First thing for you to try is to disconnect the rear outputs from your head unit and see if that resolves your issue. If it doesn't, then for speaker level inputs to a bridged amp I think you'd better read the amps manual. If you don't still have it you might be able to find it on-line. If you're still struggling post up what amp you have and post up a picture of all your speaker connections on the amp (input and output) and we'll try to figure out where you've gone wrong. I take it the head unit was working fine before you hooked it up to the amp.

 

I'm suprised though because I thought most mp3s are only stereo anyway so front and rear wouldn't matter..

I suppose to solve my problem I need to snip the rear or fronts (because I soldered them together lol).

I'll let you know how I get on

 

Ok, so I snipped the the rear inputs coming from the HU, which left me with front inputs only am I to link the 4 channels together on amp or keep it as 2 channels?

I went ahead and did two channels only but found one of my speakers are really quiet. Tried fade and balance, fade worked balance still a bit funny, so either one speaker is starting to go or I'm missing something..

 

Its entirely dependent on the amp. Some require you to loop outputs together, others have an onboard switch. You absolutely need the manual to know how bridged connections work.

The quiet speaker may be a blown channel on the amp due to wrong wires...

 

hmm, but if its connected as bridged on output then surely both front/rear or left/right will go, not just one?

I bridged the output correctly (as its labelled on the amp, and also in manual) its just the input I am stuck on (which doesn't say anything about input in manual).

 

hmm, but if its connected as bridged on output then surely both front/rear or left/right will go, not just one?

I bridged the output correctly (as its labelled on the amp, and also in manual) its just the input I am stuck on (which doesn't say anything about input in manual).

It depends if you accidentally wired the output of one into the input of another... that's only one case, it might just be the inputs again.

I would be tempted to do the following;

Take a single known signal (even take it from an MP3 player or something), and apply it to each of the inputs in turn. Whichever one fires up a speaker is one to mark as 'good'. Once you know you have two good inputs and two good speakers on the other end, then you can turn back to the head unit.

Again, a process of trial and error. Try each of the head unit outputs in one of the amp inputs. When you get sound, use the fader and balance to find out what that connection actually is. Don't assume that the wiring diagram is correct. Once you've mapped all four corners, then pick the two front ones as inputs into the amp.