Need help fast with hum

[BC Dave]

Hi,

I posted a question within a post below and have received no response. I have a system problem that's driving me nuts. A few days ago, while listening to TV through my home theater system, my sub started humming very loudly. I think it was a 60 cycle hum and it started out loud and got louder by the second. I unplugged the sub, plugged it back in and everything was fine, for a day, till it happened again. It's not a problem with the sub, because I bought a new sub on the weekend and also replaced the cable with a Monster Cable patch cord. So last night, with the receiver off, or in standby mode at least, I stuck my hand into a port on the sub to feel how large the driver magnet is and as soon as I touched the magnet this huge hum came through the system. I must have activated the sub's auto-on function. Now every time I plug the sub in there's an instant superloud hum and it won't stop. Before I go to all the trouble of disconnecting my Denon AVR-1603 receiver (still under warranty) and driving it 40 miles back to the shop, can someone shed some light on what's causing this problem and why it is suddenly occurring after many months of flawless operation? Many thanks!

[gonefishin]

At first, just tryo to eliminate various things. When you make a change...try to only make one change at a time. This way you can be sure what was causing the problem, when/if it goes away.

I imagine this is a powered sub? I would try keeping everything the same...but plugging the sub into a different outlet/circuit. See if this changes anything. If not, you could try to lift the ground using a 3prong to 2prong adapter (cheater plug). You don't really want to leave things like this...but at least you can narrow in on where the problem is. Are there any changes you've made to your system? Anything? new component, new interconnect, a change of location or outlet use? Have you had any lightning storms in your area recently? Another area to try is swapping interconnects.

well, this should get you started...along with the advice left by others as well.

good luck!

[BC Dave]

Thanks for your suggestions. The sub is powered and brand new (Paradigm PS1000v.4). The problem started the day before I bought it. I wanted to see what difference having two powered subs in the system would make so I brought my Mirage BPS150 into the room and used a y-adaptor to use both subs simultaneously. After operating for a minute or two, both subs started humming like hell. I quickly shut everything off and unplugged both subs. Then I carefully plugged one sub back in and everything worked perfectly, for one day. It happened again the next day, then everything worked great for two more days, until last night. The power cord on the Paradigm has two prongs, one of which is wider than the other. No lightning lately. System works fine with sub unplugged. I replaced the RCA plug from LFE out to the powered sub, but the problem persists. cheers.

[cam]

Thanks for your suggestions. The sub is powered and brand new (Paradigm PS1000v.4). The problem started the day before I bought it. I wanted to see what difference having two powered subs in the system would make so I brought my Mirage BPS150 into the room and used a y-adaptor to use both subs simultaneously. After operating for a minute or two, both subs started humming like hell. I quickly shut everything off and unplugged both subs. Then I carefully plugged one sub back in and everything worked perfectly, for one day. It happened again the next day, then everything worked great for two more days, until last night. The power cord on the Paradigm has two prongs, one of which is wider than the other. No lightning lately. System works fine with sub unplugged. I replaced the RCA plug from LFE out to the powered sub, but the problem persists. cheers.
Maybe it is an appliance in your house. Could be a fridge, a deep freeze in your basement, furnace or air conditioning, or maybe something small like a toaster or a light switch. Next time it starts humming, unplug them right away and try another outlet in your house. If another outlet doesn't make your sub hum I would go to your breaker box and find out what else is on the curcuit that does make your sub hum. Trouble shoot your house before the sub.

[Smokey]

Couple of thing you can check out.

Move around you [IC] cables, especially the ones that are close to [back of] TV or power cords. Also sometimes RCA accommodate dirt inside the contacts, so unplug all of audio IC, clean them and push them back in securely.

Also alot of Hums can be caused by Cable TV or satellite that is feeding the TV. Try disconnect the cable to the TV see if hum is effected.

Good luck.

[kfalls]

Hi,

I posted a question within a post below and have received no response. I have a system problem that's driving me nuts. A few days ago, while listening to TV through my home theater system, my sub started humming very loudly. I think it was a 60 cycle hum and it started out loud and got louder by the second. I unplugged the sub, plugged it back in and everything was fine, for a day, till it happened again. It's not a problem with the sub, because I bought a new sub on the weekend and also replaced the cable with a Monster Cable patch cord. So last night, with the receiver off, or in standby mode at least, I stuck my hand into a port on the sub to feel how large the driver magnet is and as soon as I touched the magnet this huge hum came through the system. I must have activated the sub's auto-on function. Now every time I plug the sub in there's an instant superloud hum and it won't stop. Before I go to all the trouble of disconnecting my Denon AVR-1603 receiver (still under warranty) and driving it 40 miles back to the shop, can someone shed some light on what's causing this problem and why it is suddenly occurring after many months of flawless operation? Many thanks!
I'm a bit confused. You say you had the receiver off when you put your hand through the port to touch the magnet and suddenly you heard the hum through your system. Do you mean through your entire system (with the receiver off), or just the sub? You say you have already replaced the input cable between the sub and receiver. The first thing I would do is unplug the receiver from the sub. If it still hums, the problem is within the sub. My guess, especially since you state the problem can go away for a day or two, is either you have a bad capacitor in the power supply which is slowly loosing its charge no longer filtering out the AC, or you have a loose internal signal wire which is getting grounded when vibration makes it touch a grounded surface.

[BC Dave]

To clarify, the receiver was not powered up but is always receiving power when plugged in because a red light stays on all the time. The sub has an auto-on function so I guess I triggered that upon touching the woofer magnet. The hum came only from the sub, which was brand new. Also to clarify, I had TWO other subwoofers plugged in the night before I bought my latest sub and the problem happened with them too, so it's not my new sub. Last night I unplugged the sub cable, reattached it and plugged the new Paradigm sub back in. At that point everything was dead quiet when I powered the receiver up. No problems since then, but I'll bet it will happen again.