Woofer meltdown (1 Viewer)

[AndrewKC]

Yesterday after I had finished watching a movie, I left my receiver and external amps (which drive the woofers on my front speakers) on, but with no signal. Perhaps half an hour later, I smelled melting plastic. I had no idea what was happening so I turned everything off and disconnected it. I touched my receiver and amps, and I found the amp driving my left front speaker was sizzling hot (this is 15 minutes after it was turned off). So I assumed my amp was fried.

Today, I decided to reconnect my main speakers without the woofer amps, so I would power them only with the receiver. I expected the bass to be weaker, but it was really pathetic. I discovered the front left speaker's woofer wasn't moving at all, so I took the grille off and noticed the dustcap was melted. I took the woofer out, and I think I'll see if I can buy a new one or have this one repaired.

Anyway, my question is if anyone has heard of anything like this before, or if anyone has any idea how to determine if it was the woofer that was bad or the amp? I have some reservations with hooking the amp to my other speaker to test it out, that's why I'm asking.

 

[Michael R Price]

Maybe the amp got damaged and started putting a DC rail voltage on the speaker output. That would definitely heat up both the speaker and amplifier. But if it did happen, you probably would have heard a loud "pop" noise at some point. I damaged an amp once and that happened, sort of a brief static and loud pop (woofers jumped out at me) and then the fuses on the amp blew. There was 45 volts DC on the output.

How powerful is that amplifier? Is it rated as DC-coupled (frequency response extends to DC)?

 

[AndrewKC]

Michael, the amp in question is rated at 120 watts at 8 ohms, 165 at 4 ohms. I'm assuming the driver is 6 ohms or less, because the whole speaker (woofer+ 2 midranges + tweeter) is a 6 ohm load. I looked at the manual, and its only rated to 25 Hz, so I don't think it will go to DC. And no I didn't hear a pop, but it may have happened while I was watching the movie and I couldn't tell. Also I noticed the part of the amp that got the hottest was the power supply.

This whole thing is annoying me, I had to replace my receiver less than a month ago, now my amp/woofer? How did you damage your amp when you did it? I don't really turn my system up unless I'm watching a movie, and even then, it's well below the limits of my speakers. I hope the woofer doesn't cost too much to replace or repair, but I fear it may cost over 100 dollars.