Odd feed back...car and HU off, amp on

[snuffdubunny]

Hi! New here. I tried searching, but my problem is very specific.

Amp is connected correctly, 4ga power and ground, it's a boss r1100m monoblock. The remote turn on is set up with a switch to manually turn it on or off. One dayton audio rss315hf 4 and another, crappy xplod from the 90s in its own box of course, wired for a 2ohm load. I know it's not good to have 2 different drivers, and plan on replacing the xplod with another dayton, but this is my current setup. Both subs are fully functional, as well as the amp.

My problem is this, listening to music, thumping along pretty good, pull up to a stop and turn off the car. Amp is still on, as I have not hit the switch yet to turn it off (which I always do before getting out of the car), head unit turns off with the car, and suddenly the subs start to feed back a 55hzish tone that builds to as loud as the amp will go. It doesn't do it indefinitely, within a second or so of reaching full volume it stops suddenly.

Any ideas? I want to figure this problem out/correct before I drop another dayton in there. Any help would be much appreciated!!

Click to read more...

 

[snuffdubunny]

Suppose i should add a couple things, car is a 2012 mazda 6, ground location is a passenger side seat bolt, paint scraped off, and not only the power wire but the remote turn on lead have fuses (60 for power, 15 for remote)

 

[brian84corvette 10+ year member]

manualy turn off the switch 30 seconds before you turn off the car. when the headunit is turned off - id imagine that feedback of some sort or electrical interference noise is being generated to your amp. pretty much no way to stop that. so remember to toggle off before you turn the car off.

 

[snuffdubunny]

Thank you. I suppose I could have figured this out for myself hah. But I did notice with the amp on one sub, 4ohm load it did not do what I described above, ever. Probably something to do with the increased power on a lower ohm load. Anyways thank you for your help!

 

[CrossoverOre 10+ year member]

If you are still using the factory head then it is a simple feedback issue. I would guess the reason it doesnt do it with only one is there is not enough sub cone area to start the feedback. Whats happneing is the subs are pushing the mids which are feeding signal back through the loc to the subs and this perpetuates. Either turn amp off first or connect to an acc source so it just turns off with the key.