Rear Speaker acting like a MIC through my Subwoofer

[willy_manilly]

Hi there, i have a 2004 VY Calais, and i have installed a Subwoofer using a Low Pass Filter. or LOC.

Its tapped into the rear right speakers, when ever i tap on the speaker the bass comes through the Subwoofer... its like the speaker has turned into a Mic when the stock blaupunkt headunit is turned off.

Im not sure whats causing this, and when the headunits off i get this constant HUMM noise through the Sub.

I have tried just going from the rear channel into the converter, but it seems the headunit has some system where if it does not detect the speaker it sends no output.

Anybody have any ideas on this issue?

[holdenboy]

So your using the rear right speaker (not subwoofer on the parcel shelf) wiring for the line out converter, then out of the LOC to the amp's inputs?
If so then the input side of the amp is fine.

How have you got the power (+), earth (-) and remote wires connected, i assume you have ran a power cable straight from the battery for power and a cable straight to metal of the car for earth?
Im thinking the amp powering the aftermarket sub isnt turning off with the stereo. Where did you get your source for the remote wire?

[StoneX]

Speakers are microphones... They converter electricity into sound or can do it the other way and turn sound into electricity.

Amplifiers have a remote/system turn on connection which is used to turn it on... Your amp is not being turned off when you turn the head unit off, so connect a switch to the remote wire and do it manually. Mount it somewhere near the drivers position so you can flick it while driving.

[AmmoJammo]

wouldn't this result in feedback?

how can it not? the output from the subwoofer will be picked up be the rear speakers, and fed back into the subwoofers amplifier, resulting in feedback.

might I suggest you remove the rear speakers?

[willy_manilly]

Well i have tapped into the back parcel speakers, i have grounded the amp in the boot from a bolt thats up the top, it all works, when i turn off the headunit the amp doesn't turn off. However when i turn off the car the amp does turn off.

If i tap on the rear speaker i get bass through the Subwoofer.

Its just stupid, i can't seem to work it out, and if i just go straight into the LOC and not go into the speaker i get no output from the amp.

Im stuck for ideas.

EDIT: I just found out the rear parcel shelf speakers are already amped by a mini amp, so i need to tap into them before this amp, or use the rear door speakers.

[holdenboy]

Yeah i was about to mention that......the parcel shelf speakers are actually stock subs. Tapping into these wires probably wouldnt be the best idea, take the signal from the rear speaker (door) wiring.

So i assume youve taken the power for the remote wire from a source of accessories then......it may help if you took it from the stereo's acc wire, it may not.
Do you get any on/off "thumps"?

[StoneX]

wouldn't this result in feedback?

how can it not? the output from the subwoofer will be picked up be the rear speakers, and fed back into the subwoofers amplifier, resulting in feedback.

might I suggest you remove the rear speakers?

Nah, a speaker acts as a really inefficient microphone. He's just hearing noise because he's pushing on the speaker cone. The humming is because his amp is on constantly and picking up noise in the wiring. This would not be audible with music playing.

Already explained how to fix it... Make the amp turn off at the same time as the stereo with either a manual switch or find something that turns off when the stereo goes off... Power antenna wire would work unless the stock head unit turns the antenna off on CD.

[AmmoJammo]

Nah, a speaker acts as a really inefficient microphone. He's just hearing noise because he's pushing on the speaker cone. The humming is because his amp is on constantly and picking up noise in the wiring. This would not be audible with music playing.

I've seen parcel shelf speakers abused by the pressure created by subs in the boot to the point where they bottom out, with no signal being fed to them.

I don't see how you can have a microphone (speaker) that is effectively feeding a signal to the amplifiers input not cause feedback....

I guess if the signal path is too short it may not be an issue..

[willy_manilly]

Nah, a speaker acts as a really inefficient microphone. He's just hearing noise because he's pushing on the speaker cone. The humming is because his amp is on constantly and picking up noise in the wiring. This would not be audible with music playing.

Already explained how to fix it... Make the amp turn off at the same time as the stereo with either a manual switch or find something that turns off when the stereo goes off... Power antenna wire would work unless the stock head unit turns the antenna off on CD.

When i tap on the rear parcel shelf, i get the thump through the subwoofer, its actually kind of cool, however when the thumb starts, then the sub just goes nuts and produces this loud constant humming noise.

Im going to try to tap into the door speakers today, any diy's on removing the doors?

Cheers

[MiggzvsC0MM0D0RE]

Here's an idea run new wire. don't tap into the wire's from other speaker's. Brain's people!