External USB2.0 HDD enclosure causing speaker/subwoofer hum

[Goi]

Hi guys.
I have 2 external USB2.0 HDD 3.5" enclosures that when powered on and connected to the PC causes my speakers/subwoofer to hum. It's more obvious on the sub since the hum is really low and I don't think my speakers are able to reproduce those frequencies well. It's probably a ground loop problem, but why would it be reproduced through my soundcard to the sub? Also, I notice seeking sounds coming from my speakers when there's any HDD activity on the external drives.

Does anyone know how to fix this? Thanks!

 

[PurdueRy]

I would try a different sound card(since you seem to have many) and possibly a add on USB card

 

[phisrow]

Try a few tests to see how the interference is getting into your audio subsystem. First, try moving the enclosures closer and farther away from the speakers, and see if there is any change. If yes, you probably have a stray EMI problem. Wacky games with grounded tinfoil are in your future.

If no, try running the enclosures without their cables connected to your machine. If that solves the problem, you might want to try using a hub to isolate the enclosures from the computer.

An isolation transformer on your audio line might also be a good idea.

 

[Goi]

PurdueRy, I actually tried both my Audigy2ZS and the onboard audio, and both are affected.

phisrow, I'll try those tests. My sub is on the floor below my table, on the RHS, and my monitor is dead center on the table, with the 2 drives to the left and right of the table. There's probably 1' and 3' between the drives and the sub respectively.

 

[Goi]

OK I just tried moving the drives further away, and it did jack. W/o the cables connected to my machine though there was no humming, so the cables are transmitting the humming noise to my computer. In addition, whenever the metal parts of the USB connectors touch, I hear humming and see really tiny sparks. Is that supposed to happen?

As for the hub, would it matter if it's a powered hub or not?

 

[corkyg]

Are the externals powered separately? 3.5 drives almost have to be. Have you tried grounding thos cases to a good earth ground? Sounds like A/C hum, and it usually stems from a grounding problem.

 

[Goi]

Yes the externals are powered separately with their own 3-pin power plug, so they should be grounded. What do you mean "grounding thos cases to a good earth ground"? It does sound like A/C hum, but I'm also getting seek noises when the HDD is active so I dunno...could be more than that.

 

[corkyg]

If it is according to code, your electrical outlets have a good earth ground. That means that the chassis and conduits are ultimately connected to Mother Earth. That is what the round pin in a three prong connector is for. Most boxes have a green screw that the female plug is grounded to. A wire to that ground - a radiator, or a water pipe, or a conduit connected to your external device can work. It you do not have three pronged A/C plugs, they may be polarized, and that helps. If they male plugs are the same size, try reversing them.