I have done some research lately for this issue and while I think I have a lead on it, I need some help. I have only had one system before, which I knew almost nothing about. I missed having a little bit of bass in my wrangler, so I ordered a small 10 inch shallow mount MTX sub, I believe the terminator. Its 150 RMS and 300 MAX. great. small sub, not alot of room in my jeep, makes sense. I have a Kenwood KAC606 (the 2 channel, 75x2) laying in my basement, its old but I think it still works, and its bridgeable. through a little research its supposed to be at 4 Ohms when bridged, so I got the 4 ohm sub. okay. good so far.
My old wiring kit was for a system pushing around 1000 watts, so it was too big to use most of the parts. I ordered a new wiring kit for like 20 bucks. okay. I did reuse my old RCAs (monster cable) because the new ones I got looked like junk. So I get it all wired up, Build my box. my speaker wires are soldered to the sub, and I think two are connects were soldered because the crimps were garbage that came with the kit. anyways. everything is a good solid connection there. I wired the main ground wire the same place I had my old system wired. However the tub of my wrangler is bedlined, so I may have to scrape some more off of that for a better ground. I also ran the ground from the head unit to the same spot, as per instructions from MTX.
I noticed there was a small ground for the amp itself, I had never seen that before and I didn't have a wire for it, so I didn't bother with it. yeah go figure, I was in a rush. I am going to add that. anyways, the power I tapped into the ACC power, for the on, and went straight to the batter for the amp power. everything is hooked up correctly.
I never sealed my box completely because I wanted to make sure the amp worked properly first. so I wired it all up, and sure enough it plays. sort of. It sounds trashy (small box, not sealed well, etc.) and it makes a strange pulsing feedback noise maybe 1-2 times per second. I kept all my gains low, and messed with gains on both the amp and HU. messed with the low pass and hi pass, tuned the HU to 80 hz, for the lows, turned the amp from L to stereo, etc. turned everything down to try and get rid of feedback. Nothing. It will play the bass, but sounds choppy because it will cut out and thump every second or whatever. and at higher volumes it will completely stop playing, and only thump.
I messed around with all connections some more, made the ground a little better. etc. and nothing. I am going to really get to some good bare metal and ground out that amp next when I get some sunshine. I am also going to swap RCA cables. I am really hoping the amp is faulty. Other than that, my thoughts are that maybe my ground is not connected correctly to the HU, because there is a mess of wiring behind my head unit from the PO. I did my best to find the ground using a voltmeter. but who knows. my electrical knowledge is a bit shaddy, I am not expert.
I would be thankful for any insight or suggestions anyone can give.