nnnggg

Hi, i just install a amp and sub in my trunk today. 12V power directly from car battery with inline fuse, ground wire I used a hole in the trunk, i sand the surface to remove the paint and tight it down with a screw. Audio from the headunit and the remote cable to the headunit 12V power. I notice that my subwoofer sound more powerful before the engine start, after the engine started the subwoofer sound weaker. After i stop the engine the subwoofer sound powerful again. It had a significance different between the engine started and stopped. Can anyone tell me is that normal all i do something wrong of the install??

grumblemarc

iTrader: (4)

Before start, amp pulls straight from battery with no competition from other components. Once car is on, other components AND the amp are drawing power from battery. Weak alternator is probably not able to keep up with keeping the battery fully charged. That's my theory anyway.

People will recommend you get a capacitor.

nnnggg

Is it the only way to fix this problem is add a capacitor??

grumblemarc

iTrader: (4)

You could get a high output alternator.

If you're looking for a cheap and easy fix, there isn't any.

Acu

+1

nnnggg

I check today, the amp have a red light on when the engine started and no bass from the sub. 1-2second after the engine stop, the sub turn green light and the sub is working, I double check the remote wire is go connect. Is there any reason why this happen? Thanks

grumblemarc

iTrader: (4)

What have you done since the first post? Double check how you have that wired and grounded because first you said it was weak and not it won't operate while the car is running?

nnnggg

Before I put the sub in the trunk so when the car started it sound weaker and i feel it with my hand is vibrating. but i think the weak bass i hear was from my rear speaker and the vibration also from the rear speaker. Today I check the sub and amp at night, i move the sub to the rear seat, and try to feel the sub with my hand when engine started but is not work. I saw i red light on the amp, is not a bright red light so I miss it on daytime. The fact is the amp is working when engine no running and stop working as soon as the engine started and it working work again after engine stopped. Hope you can understand what I'm trying to say. thanks

grumblemarc

iTrader: (4)

Recheck how you have wired it up.

nnnggg

I checked voltage is normal, good ground and power, remote wire is good connect.

grumblemarc

iTrader: (4)

"Good" doesn't tell me anything. Explain or draw, in detail, how you have everything wired up.

nnnggg

Before the engine start is 12.47v after the engine start 14.4v. I check the voltage from the amp power input, i also measure the voltage from the battery and the are same as above. I test all wire again, by remove the speaker wire, is green light before engine start and red light after engine started. I do the same things for relocate the ground wire, connect the remote wire to the amp power input and other 12v wire. It is same before engine start is green light, turn red after engine started. But i found a thing is when I'm not using power directly from the battery, I took remote wire from head unit connect to power input of the amp and run a wire from the amp input to the remote of the amp. You know what, is green light before and after engine started. It working if I'm not using power from the battery. Is it possible the battery have to high voltage for the amp, so put the amp in protection mode?? Or is it the power cable/ fuse have problem?? Is it ok/ save to take power from the head unit remote wire??

underrated

iTrader: (3)

Where are you getting the constant 12v to the amp from? What brand is the amp? What size wire are you using?

linkarmy09

Take the amp out put it next to the batter with a short cable put it to the 12v and ground and see if the issue is still there. If its not the problem is in the wireing and if it is still there then its going to be the amplifier.

linkarmy09

"took remote wire from head unit connect to power input of the amp and run a wire from the amp input to the remote of the amp. You know what, is green light before and after engine started. "

OK im having a hard time understanding. Did you jump the remote turn on input to a to the 12v input? instead of using the remote turn on from the HU?

nnnggg

I took the wire from HU remote connect to amp 12v input. have another wire from amp 12v input to amp remote.

grumblemarc

iTrader: (4)

WHAT CAR IS THIS IN?!!!!!

This should be less than simple so I don't understand this weird problem you're having. Did you wire the amp straight from the battery? Is it fused? Where did you ground the amp? What gauge wire did you use? Is the gauge of the amp power wire the same as the amp ground wire?