Subwoofer Amp "popping" - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 10 Old 02-20-2011, 09:44 AM - Thread Starter
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I have an NHT SA-3 subwoofer amp. Recently it has developed an issue that I'm trying to troubleshoot. Whether on and idle or playing material, it will periodically "pop" similar to a turn-on thump. I have not had a chance to take the cover off to peek inside but am trying to get ahead by learning about common/potential component failures that would cause such a condition. I'm hoping it's as easy as dust bunnies inside the chassis that need to be blown out or something. Any thoughts appreciated.
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post #2 of 10 Old 02-21-2011, 08:45 AM
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After several years, the amp on one of my subwoofers would make an occasional pop sound. I chose to ignore it but after a few more years the popping sound was occurring relatively often. At that point, I purchased a new subwoofer amp.

An alternative is to get the service manual, a volt/ohm meter, and suitable soldering equipment. You might get lucky by replacing the main power capacitor (and have that solve the problem).
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post #3 of 10 Old 02-21-2011, 02:28 PM - Thread Starter
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I was wondering if it might be a cap failing. I'm nervous that continued use may cause damage to the woofer. I'll get into it tomorrow to see what I can find.
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post #4 of 10 Old 02-22-2011, 03:44 PM
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I doubt if the popping would damage the woofer but then I don't claim to be a real expert or EE. From my experience the popping could be a lot of things; a failing ground; a bad cap or transistor; a loose wire (ants like to chew on electric wires); or a bad connector. It could even be a bad cable; be sure the cable interconnect or wires are in good condition and tight, with no exposed wires. Always check the cheap stuff first (cable,wires).

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post #5 of 10 Old 02-23-2011, 07:06 AM - Thread Starter
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Well I didn't get a chance to pop the cover off but did a little troubleshooting. The sound occurs regardless of whether upstream components (BFD/Yamaha receiver) are powered up. It also occurs when the upstream components are disconnected from the amp. It seems to take about 5 to 10 minutes after powering up the amp before it first happens. It also seems to happen more frequently at idle/low output usage than when I'm wailing on it with heavy club/bass music. Will hopefully get under the hood soon to see if there are any obvious physical signs. Power cord and speaker wire are fine.
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post #6 of 10 Old 03-07-2011, 10:43 AM - Thread Starter
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I finally had a chance to take the cover off this amp and look around inside. There were a lot of dust bunnies as suspected. I blew it out with some compressed air and inspected the board and some components for obvious signs. The only things I noted were a discoloration in several places on the board that "looked" heat related (I'm no expert), a copper looking coil that was barely touching the component next to it and some kind of black adhesive/paste looking substance at the base of the big caps. I gently nudged the coil to separate it from its neighbor on the board. The black substance at the base of the caps may well be normal and have existed since initial construction or may be some kind of leakage, my lack of familiarity leaves me only guessing. I took the opportunity to re-seat all removable connectors from the board/jacks to freshen up contact points and reassembled. Six hours later and I've not heard a pop out of it. I did also reroute all of the signal/speaker/power cords in an effort to minimize any potential issues there, though I feel I had previously eliminated this as a source for the problem.
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post #7 of 10 Old 03-07-2011, 01:16 PM - Thread Starter
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post #8 of 10 Old 03-07-2011, 03:45 PM
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Unplug the sub from the audio source and see if it still does it. Many times the pop is another appliance cycling on or off (in my house it turned out to be the tankless hot water heater) in the household and the noise is induced in the cable.

Lot's of low rent stuff stacked up into a medium rent pile.
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post #9 of 10 Old 03-08-2011, 03:10 PM - Thread Starter
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Quote:
Originally Posted by digital desire View Post
Unplug the sub from the audio source and see if it still does it. Many times the pop is another appliance cycling on or off (in my house it turned out to be the tankless hot water heater) in the household and the noise is induced in the cable.
The problem has been solved. See above.
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post #10 of 10 Old 03-16-2011, 01:04 PM - Thread Starter
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I spoke too soon. I made it about a week and then was missing the bass from my music. I power cycled the amp and it came right back. Five minutes later it popped loudly several times and stopped working, accompanied by burning smell. Now no sound at all. Have not looked inside but thinking it's time to move on.

Now I need a 250W sub amp (not a plate amp) for modest money. So far I've seen Pyramid and Pyle, not what I had in mind. Maybe a Dayton or small Pro amp from PE? Any thoughts?
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