Rumble from subwoofer and amp recovery mode

[ampageg2]

Hi everyone, first post here, so hopefully this fine community can give me the answers I'm looking for.

I currently have an entry level sound system and have been having some issues with it. I have a 400W Dual amplifier and a small 8" MCM subwoofer. The head unit is a JVC Arsenal KD-AR555. The system was originally wired by my friend who has been into car audio for years. I know quite a bit about EE so I took a look at the loop myself and I don't see anything. I've had the system for around 5-6 months now.

A few weeks ago, I was getting some bad distortion with the subwoofer - a rumbling noise while playing music. I turned down the gain and that seemed to fix it for a few days, before the entire system just stopped. The fuse in the amplifier blew and I replaced it thinking that may have been the cause. Within minutes, that fuse also blew.

I wasn't sure if I had the subwoofer leads wired correctly, so I switched the polarity on the them and the fuse stayed intact - though I could've just had a bad fuse. My amplifier went out of recovery mode for a few minutes, so I turned down all the settings to try to tune the gain and frequency again. Almost as soon as I turned the gain up, the rumbling from a few weeks ago returned. I turned the settings back down. It is once again in recovery. I don't see any issues in the wiring.

I've also noticed a popping sound coming from the subwoofer even with no audio output. From what I've seen around the net, it seems to be a capacitance issue with the caps in the amp. They all look okay to me, but I'm not sure. I don't want to just start replacing things without having a good idea of the issue.

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[garychoffmann 10+ year member]

Check the voicecoil of the sub first to see if the sub is not blown. Use a dmm to see its resting impedance

 

[ampageg2]

How do you use a multimeter for that? I know how to use it, just not what to check.

 

[garychoffmann 10+ year member]

Put the leads on the speaker terminal and set it to ohms and see what it reads

 

[CrossoverOre 10+ year member]

id be looking at that amp as the problem

 

[ampageg2]

Took it to a local shop and they said it was a bad amplifier. I replaced the amp and it wasn't going into recovery mode like the old one, but whenever the bass should've been channeling through, the LED would flash red signaling recovery. I figured it was also (assuming the amp was bad to begin with) the subwoofer and replaced it today. The new amp isn't going into recovery at all now and the bass is pumping like it should be. I had some problems with my alternator a few months ago so that may have started the problems and they just gradually got worse.

I don't know what's wrong with the old subwoofer, because it's reading at 4Ω and when pushing on the cone it still scratches. Maybe something bad with the connections inside? I don't know, but the sub only cost $25 to replace (reused the old box).