How can i hook up a second battery to my MTX 4105d amp

You should always wire your amp directly to your battery. and an inline fuse of about 100 amp. about 3-5 feet from the battery.

Your basic crossover is going to have a power (+) and ground (-). Your power wire goes to the battery, and your ground goes to the frame. You will need to hook up your RCA or speaker wires to the input side. Then hook the other two RCA connections to your amp.

Ya. Just hook one sub to your amp (bridged) and hook the other sub (positive and negative) to the first subs positive and negative

could be not enough voltage or the settings on the amp are not correct for the sub you have its a feature that MTX put on thier new amps

Power hungry unit and the battery may not be enough for the amp, could be a bad cell in the battery.....

The more amp you are pushing the better. Better too much amp then not enough. How many watts per speaker? less then the amp I hope. When you need decibles the more air you push the louder it will be. Enclose in a MDFB enclosure or plexiglass and feed towards each other and port the box to the sides. This will cause some annoyance. We ran 2 rockforts @1000 watts and abtained 137dc before the back windshield blow out,,lol

Hello tonytone54, The ground should go directly to the vehicle frame, never through a cap, fuse, or anything else. Also, if you are connecting positive through a cap, make sure that you charge the cap before connecting it. Hope this helps.

this is a signal crash either your speaker wires are crossed (wrong wiring phase) or your RCA jacks need replacing also it could be inside your amp the solder lines may have fused. If after checking and replacing wiring problem persists return to MTX for repair.

my amp is blowing fuses?? any hints?

check your fuse up front first. some amps will turn the light on with only the remote wire (the 12 volt signal from the head unit). That may be your issue. If not you need to check your signal input. try hooking the rca's to a diffrent source, i.e. other radio your tv anything with Rca out put. If still you get nothing then pull your subs out and take a regular 9 volt battery and touch the leads to the positive and negative of the sub. Just for a moment though if the subs move when they come in contact with the charge from the battery then my last suggestion would be to take it to a store where you can have an authorized tech check out the equiptment. Good luck