I have a Alpine MRP-M500 that I'm going to power a 10" Alpine SWR-10D4 with @ 2ohms.

This amp has a turn-on feature using the speaker level input so it eliminates the need for running a remote wire.

My questions are

1. Can I tap it into the stock rear sub + and - to get signal, or does it have to be a speaker?

2. The harness has up to 4 channels, so do I use the CH1 + and - leads and leave the other ones blank?

I removed my system from my car 2 years ago and still have a LOC in the trunk still tapped in to the stock wires. I had a friend install my setup years back.

The reason I want to use the speaker level input is because it has the remote turn on feature built into it and also I heard using a LOC isn't good and shouldn't be used.

I'm hoping I can just tap into some of the rear deck wires instead of having to go all the way to the amp

 

yes and yes

 

Thanks.

Will I be able to reach the stock subwoofer + and - wires from inside the trunk?

Or will I have to remove the rear seats and rear deck just to tap the + and - wires?

Where did you guys ground your wire for the amplifier? I see there's a ground bolt in the trunk but the fuel pump is grounded to that bolt. I'm afraid of using that ground just incase anything shorts out I don't want a dead fuel pump..

 

So to answer my own question yes you can reach the stock subwoofer + and - wires from inside the trunk without removing the rear seats. You just have to pull down the trunk liner and you'll see a red and red / black wire. That's for the rear sub.

And for the ground I ended up bolting it near the fuel pump ground. Theres another circular opening about 2-3 inches to the right of the fuel pump ground and I found a bolt and nut that fit it perfectly. I sanded it down to make sure it was bare metal. Checked continuity from that ground to the fuel pump ground and another star ground in the trunk by the navigation disc and all was good.

 

1 thing to keep in mind: a lot of signal sensing turn ons need a decent amount of AC voltage to kick on the amp. Especially when using a signal that is ~100Hz and down so you may run into situations where if you have the volume relatively low the Alpine amp will turn off.

If it were me, I'd just run a standard 12v turn on. It's not like this car has some crazy MOST amp turn on.

 

Thanks for the heads up.

The whole reason I wanted to go with the speaker level input was because of the "auto turn on" feature but now it sounds like I might just need to use the standard 12v remote turn on wire anyways.

I'll just wire up a remote wire just incase the amp kicks off in low volume situations like you mentioned.