had a customer w a 98 expedition got an amp/sub package (profile 700m w pioneer tsw 12's, entry level package). Used a line level converter off factory speaker leads, (had factory sub but I'm not sure which exact speaker leads were tapped by line level) and bass sounds good but there is a somewhat loud hum when the key is turned off (turn on wire is fused at ignition) and a very loud hum when the radio is turned off while the engine is still running.
My tech say every one he has ever done like this does that but I just can't accept that. He tried to add a relay on turn on wire but I think it is coming from line level.
any suggestions?
He tapped into the rear speaker wires for signal. The problem is when the woofer moves it creates bass and the rear speakers see the bass and they move which makes them produce voltage and the converter sees it as sound so it sends signal to the amp and the cycle starts all over again. A simple fix may be to reverse the polarity of your sub. the other fix is to put the LOC on the front speakers.
So is this still possible when the amp is "turned off" by the remote turn on wire? I mean that if the remote wire "loses" its 12v (through a relay to interupt), can the converter producing voltage still send it through the amp when the amp is figuratively "off"? thereby producing the loud hum?
If it had the factory sub there is a remote wire in the harness of the factory amp. If he gets remote there the amp will turn off when the radio is off.
If the amp is off the cycle can not continue.
Hey dude I had the same problem when I put my system into my 05 Neon. I figured out that my problem was that I had tapped into the rear output with them still connected to the factory speakers. When I unplugged the rear speakers it worked fine, so I installed a separate amp to run the factory front and rear speakers. I too had installed a loc. All is well now.
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05 Neon SXT/infinity 311a/2 Polk db104 subs/vr3 400 watt to factory front and rear