[///Marshy]

Hi all,

I have just installed a JBL GTO804 sub and EDGE monoblock amp into the boot of my E90.

Using some useful tips on this forum I spliced into the speaker wires under the front seats and ran these to the back of the car. The amp I am using has a high level input so there was no need to fit the hi-lo adapter. I wired the speaker signals into the high input, hooked up the power/ground/remote and everything worked fine. I only tested it for a couple of mins and went back indoors. GREAT! Or so I thought....

The next morning I got into the car to drive to work, and 5-10 mins into my journey all sound disappeared. The radio still works as normal and will skip between stations and CD/Aux etc but with no sound. I checked the amp I fitted and it was still live.

The only way I could get the sound back was to leave the car for an hour or so and come back to it. This has happened a few times now so I have disconnected the speaker signal to the amp as I dont want to break it permanantly.

It would seem the amp in the head unit is being overloaded and giving up. Has anybody come across this before or can tell me where I'm going wrong? Is it worth fitting a hi-low adapter and running the signal to the RCA input instead?

Thanks for your time reading this!

EDIT; My car has the base audio if that helps.

Lee

[ctuna]

Are you sure the amp is turning off?
And is not constantly draining your battery?
Backtrak and see what happens would be the
first thing I would do.

[kaigoss69]

When you tap the OEM speaker cables you are effectively reducing the impedance of the speaker circuit. I would think though that if you reduced the HU bass setting to zero/normal position that the HU amp will not be overloaded. That's because a large portion of the power supply gets used up by bass frequencies. Make bass adjustments on the aftermarket amp, not the HU!

[kaigoss69]

If the HU amp shuts down at low volume levels, you could have shorted the OEM wiring.

[alexwhittemore]

Originally Posted by kaigoss69

When you tap the OEM speaker cables you are effectively reducing the impedance of the speaker circuit.

This is true, but the high-level input on the new amp should be very high impedance, much higher than the 4 ohms (or is it 2? I think it's 4.) of the stock speakers.

My first thought would be a short as well, but if that were the case, I'd expect the headunit to shut down immediately, and if nothing else, you'd hear no sound from the stock under seat woofers OR new subwoofer.

Sorry I can't think of any solutions of my own to propose

EDIT: It certainly can't HURT to try adding an adapter. If you mean soundstorm edge, the amp doesn't look terribly high quality so for lack of any better idea, my first reaction is to distrust the inputs.

[bmw325i]

It's definetly a good idea to go back to stock and test it. If everything works, try a line output converter.

[///Marshy]

Originally Posted by ctuna

Are you sure the amp is turning off?
And is not constantly draining your battery?
Backtrak and see what happens would be the
first thing I would do.

I have checked this evening and the amp is turning off. I used the switched live of the unused loom on the left hand side which I assume is for a cd changer or OEM amp on a superior model

Originally Posted by kaigoss69

When you tap the OEM speaker cables you are effectively reducing the impedance of the speaker circuit. I would think though that if you reduced the HU bass setting to zero/normal position that the HU amp will not be overloaded. That's because a large portion of the power supply gets used up by bass frequencies. Make bass adjustments on the aftermarket amp, not the HU!

That's interesting to know thanks. I have tried your suggestion of setting the bass to zero position but the same problem occurred.

Originally Posted by alexwhittemore

This is true, but the high-level input on the new amp should be very high impedance, much higher than the 4 ohms (or is it 2? I think it's 4.) of the stock speakers.

My first thought would be a short as well, but if that were the case, I'd expect the headunit to shut down immediately, and if nothing else, you'd hear no sound from the stock under seat woofers OR new subwoofer.

Sorry I can't think of any solutions of my own to propose

EDIT: It certainly can't HURT to try adding an adapter. If you mean soundstorm edge, the amp doesn't look terribly high quality so for lack of any better idea, my first reaction is to distrust the inputs.

Originally Posted by bmw325i

It's definetly a good idea to go back to stock and test it. If everything works, try a line output converter.

I thought there could be a short, but since taking the signal off the amp everything has worked correctly (minus the sub of course). The connections I made under the seats are still the same so if there was a short there I guess it would still be cutting out. I suppose there could be a short in the amp though.


I will try an adapter and let you all know how it goes. Thank you all for your help so far

[///Marshy]

Update: Today I fitted the hi-lo adapter and ran the signal to the RCA inputs instead which seems to have fixed the problem!

Thanks for the help