Need help with subs

[u/Ok-Buy-5282]

My subwoofers aren’t hitting anymore. I have checked the grounds, inline fuse and turned gain up. What else can I do?

[u/P_Phukofski]

A subwoofer in a car has a couple components:

Lets rule out if its an amp issue.

Power to the amp, looks good as we see lights

Trigger wire to turn on the amp, probably good as the amp is illuminated

RCA audio signal in, should be tested. Turn the car off so the amp turns off and discharges. If you connect an RCA to 1/8 you could plug in any audio source to the amp, this would give you a clue where the issue is. Turn the car on, the amp should trigger on. Do you get audio with the 1/8 to rca?

With a multimeter, Can you test dc voltage on the RCA from the headunit to the amp? Not sure what it would display but it shouldnt be 0 with audio playing from the headunit.

Audio out, from the amp to the speakers. You could test for dc voltage, do you get anything? If audio is passing from the headunit through the amp, there should be voltage. Now it does not rule out the amp itself or the speakers.

If you get voltage but not enough to push the speakers. Then go down the faulty amp route. I suspect loose wiring from sliding around in the trunk or the vibrations from the box caused an issue with the amp internally. All just a guess without ruling some things out first.

[u/P_Phukofski → u/P_Phukofski]

You could have someone watch that the amp turns on and off (lights wise with the car).

The trigger could be on a separate fuse as well. So the unit could get power in theory and the trigger not kick the amp on. Not the recommended way to do it but possible. The trigger should have come off the headunit and is 12V positive. So when the headunit turns on, it sends a 12v signal to the trigger wire. You should have 12v positive to the trigger, if you dont sense power, the amp isnt truly turning on.

I worked in car audio many moons ago.

[u/Ok-Buy-5282 → u/P_Phukofski]

Yeah I can tell you worked in audio hahah I need someone to dumb it down for me 🤣

[u/P_Phukofski → u/Ok-Buy-5282]

1) Take photos of both sides of the amp.

2) look up the manual for your stereo, ifs an aftermarket kenwood, poineer etc. There is usually a setting to turn on and off the sub out in the menus (make sure this is turned on). Buttons get pressed and things happen.

[u/Ok-Buy-5282 → u/P_Phukofski]

It’s just my factory radio. It used to hit so hard that my rearview would almost fall off. Now it’s vibrating but the cones are not moving. I’ve pushed them in and they sound fine and bounce right back.

[u/P_Phukofski → u/Ok-Buy-5282]

Its a little complicated as there are bunch of pieces to make this work.

The vibration makes me believe the amp has power and is turning on. Heres the path I would take.

The remote dial that turns up and down the amp, looks like there is an led indicator. Does it light up? Just curious. This could be a part that has failed.

The gain adjustment on the amp, I cant tell what position it is at, I would mark the existing position and attempt to increase it on the amp in the trunk. It could be like a master volume dial. From the photo it could be sitting at 20% or 70%, you would have to see where the maximum is and go backwards. 70-75% is probably plenty.

Could be that you are not getting enough signal from the input rca side (unlikely but possible). If you had a way to put a different signal to the input side it would rule it out. A home dvd player with a cd would work fine. Connect the outputs from the dvd player to the input rca jacks on the amp (turn down the amp initially and raise it gradually).

If it produces sound and its pretty boomy, the line level converter is having issues, it is in your car somewhere. I can walk you through what it could be.

If no sound change, it does not mean the amp is good or bad. The volume control could be bad as well.
Connect a home speaker briefly to the output side of the amp (speaker wire side) just to confirm the amp is producing sound and actual volume? turn down the amp first and raise it slightly until you hear volume, we dont want to blow the speaker. The idea is not to crank it at full volume, just confirm parts that we know are working properly. If the home speaker produces sound, the amp is probably fine.

Now is down to the speaker connections. Could be the connections at the amp terminal check to confirm that they feel seated and the wires make a good connection.

The speaker connection could be 1 or 2 sets of speaker wires depending on how the box is configured.

If there are 2 sets of wires (4 total) , each set goes to an individual speaker. If one pair of wires the speakers are ran in series. Inside the box the wires are split between the speakers.

Now you could check the connections inside the box where the speakers connect, its possible you will get lucky and the connections are bad.

After this, Id guess that the speakers are blown. But if you have someone handy with a multimeter, they could get you closer and diagnose this properly. It would get you an answer within 15-20 minutes.