Axiom Home Page Forums General Discussion Technical Questions Humming JBL subwoofer.

Will,
As you've said, it hums even when disconnected, so it cannot be a relative grounding issue between components. Done with that one.
You've also said that it has a 2 wire plug, which I think some of the other responders have missed. Using a cheater won't change the grounding worse than it already is - it's not using the dedicated ground pin. If the 2 wire plug is not polarized, then just try flipping it and see if the hum goes away. (I bet not). But I assume it is polarized and you cannot do that. If you can use the cheater and IT is not polarized, then you can try the same thing. Perhaps the JBL is wired wrong inside. At least it would be easy to check with the cheater routine. You won't set the house afire with that test.
Good luck

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You've also said that it has a 2 wire plug.

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Whoops... I missed that on the first readthru.

Bren R.

You might have some other electrical device plugged into another outlet in the house causing the problem. Anything with a large motor, or even a small stepper motor, can cause noise to be induced on the line.

2 things to try:

Turn off every circuit breaker (or remove every fuse) in the main panel, except for the one that the sub is plugged into. Make sure that the sub is the ONLY thing plugged into the 1 remaining circuit. If the hum goes away, turn the breakers back on one by one until the hum comes back. Then, you will have an idea where to look (if your panel has labels).

Second (maybe 1st) verify that your main electrical panel has a thick, bare, copper wire coming out of it that attaches to either a water pipe on the inside of the house, or a copper rod stuck in the ground on the outside of the house. If you don't see one, or if the connection you see looks bad, call an electrician. Your whole house could have a floating ground. If you have cable TV, it should also be grounded. Noise can come in on the ground (shield) as well.

(I forgot to ask... Are the AC grounding requirements in Canada similar to those in the U.S.?)

Good luck,

Thanks guys. I'll study those suggestions in the morning when I'm more coherent. I know the plug had one blade larger than the other (polarized?), so that's out. Before trying the circuit breaker I may just take her sub back to my house and see if it hums here. Should that be the case... I'll sell her my EP350 and get an SVS 20-39+.

I forgot to ask... Are the AC grounding requirements in Canada similar to those in the U.S.?

Don't quote me on this but I don't believe code here allows for a direct earth ground rod. I've seen them in pics from the states, only time I've seen them here is back in the aerial days for grounding antennas (and grounding camper trailers)

Bren R.

Just dug out the Canadian Electrical Code (the wife's a Sparky ... sorry, Electrical Engineer). You can use a grounding electrode (rod) or, as in many cases, the ground wire is tied to the water main. As long as the wire from the panel to the ground point is continuous - no breaks, no joins.

Sean

Hate to rip this one off topic Sean, but I think the original question has been answered... was going to pick your wife's brains on something.

Started replacing plugs in the garage - four of them plus five light fixtures and the GD opener are on one circuit, one single plug (the natural place for you to plug in a block heater) is on another and is currently dead for whatever reason - I didn't look too closely yet.

Traced back the wiring - it's all 14-2 or 14-3 copper... all the way back until the buried cable coming into the garage from the house, which is, of course, aluminum (did anything GOOD come out of the 70s?).

Since I'm paranoid about AL wiring, I ran out and got a specifically listed CU/ALR duplex outlet for that one. So I have - 12-3AL coming up into the garage, the red conductor energizes the outlet I'm replacing with an ALR listed outlet and continues from there as copper as I explained. Since I usually replace aluminum wiring and have never really tried to make it safe, unsure how best to deal with it.

I'm under the assumption that the safest way to make a connection between AL and CU is through an AL rated outlet rather than pigtailing with a marrette. So the red conductor as it sits should be reasonably safe. Now the black side is pigtailed with a Marrette in the same box onto the copper run that takes it to the box it feeds, which if I understand correctly, can lead to fire (oxidation occurs, resistance goes up, hot spot, marrette melts and the spring turns into a cigarette lighter). Does it make any more sense to use the top and bottom plugs in the duplex (with the hot tab broken) to make the transition? Or will this lead to overloading the neutral? Would it be any safer than the way it's pigtailed now?

Bren R.

Bren

Katherine is off at a guide camp for the weekend so I won't be able to pick her brain until Monday. Besides, for some reason, I'm the one that does all the wiring around the house (unfair I say!!). However, in the meantime try the following link that deals with that exact issue. If you have any further questions, send me a PM and I'll see what I can do for you.

http://www.region.halifax.ns.ca/Fire/pages/wirebasics.html

On a different note to the board. My family and I will be moving shortly to Alberta, I'll have to pick up the Axiom board from there.

Sean

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pigtailing with a marrette

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hehe... I had to look this one up - I'd never heard that before.

Oh, you mean a warnut? (that's good ol' boy for wire nut).

Is the electrical connection box on a motor called a "peckerhead" in Canada?

Marrette, wire nut.....I'd heard it called a Dutch lock before but have no idea why.