I have a 2009 528xi, I just did a trunk sub set up. Is there a high voltage cut out for factory amp. I did the standard ”Tap and play” where I tapped into the factory subs and remote wire.

The issue is and high volume the sub doesn’t stay on it shuts off at about half volume.
Anyone know how to fix it?

 

Did you "tap in" and add an additional sub amp, or did you just add a subwoofer powered off the speaker wires directly?

 

Sorry forgot to update it, I figured out that I had a 4 ohm amp, and the wires I tapped are 2 ohm. So if anyone else is going to put in a trunk sub and you tap factory signal wire to run a rca adapter, make sure you have a 2 ohm amp!

 

the Ohm rating only refers to the speaker hookup… not the signal going INTO the amp… speakers are 2/4/8 ohms and depending on how you wire them, it affects how much power the amps puts out… an amp rated to put out 50w at 8ohms might be able to put out 100w at 4ohm and possibly up to 200w into 2ohms if the amp is capable of using that resistance without blowing up or running too hot…

the input side of the amp has nothing to do with the Ohm rating of the amp… a 4ohm amp only means that it can’t handle being wired to 2 ohms or less at the speaker output… a 2 ohm amp can be wired to 4 ohms or two ohms once again, having nothing to do with the input stage

If you’re using the speaker wires, you just need to make sure you use a good Line output converter and make a solid connection when you tap in or use an amp that has speaker level (or high-level) inputs… I personally used the low-level wires in the amp harness which allowed me to run RCAs direct from those wires w/o needing the converter

don’t get me wrong… I’m super glad you got it worked out… just making sure you have the right info going forward (ex sound quality competitor and magazine editor)

 

Input impedance is also measured in ohms(Ω).