60 hz hum is making me pull my hair out!

Do you have cable TV?  That's one of the biggest sources of a ground loop.  How are your TV and computer connected to the receiver?

I'm going to ride along on this one because I suspect my hum problem is related.  This is a new setup in that I've added two separate power amps for my Vandersteen 2Cs which now double as front L/R speakers, connected from the pre-outs on the AV receiver.  The hum is from these two speakers, and is volume-adjustable.

I've been able to troubleshoot to the extent that I know of two "sources" for the hum:  (1) the cable box and (2) a phono-stage for the turntable.  When I remove all of their connectors from the receiver, there's no hum.  (Actually there's still a very low one, at a level mostly covered by program material, but let's attack this one step at a time.)  Bottom line, I can only watch cable by keeping the two powered speakers turned off.  Likewise the turntable, and I can tell you that playing LPs through just center and surrounds is the perfect definition of half-assed solution.

So... I can have the amps on and enjoy full surround from the Blu-ray and DVD/SACD players, and there's no problem from reel-to-reel and cassette tape decks.  But having the cable box or phono pre-amp connected to the receiver renders the powered front speakers unusable.  These are my only sources, no computers or gaming or other devices, nor do I yet have a subwoofer in this setup -- the Vandersteens are set to "large" to handle the bass.

Prior to adding the two power amps, I never had a problem in the 15 years I've used all manner of equipment (including the cable, etc.) in this room.

Power cords:  Receiver is 2-pronged, power amps are 3-pronged, phono stage 3-pronged, cable box 2-pronged, tape decks 2-pronged.  These are spread across three power strips from outlets on two walls, and I don't as of yet have any power management or line conditioning devices.

Any pointers greatly appreciated.

You need a ground loop isolator on your cable box coaxial cable...

http://www.audioholics.com/tweaks/connecting-your-system/ground-loops-eliminating-system-hum-and-buzz

There are a number of solutions available from different vendors.

- Walter.

Quote:

Originally Posted by Chas in CT 
Power cords:  Receiver is 2-pronged, power amps are 3-pronged, phono stage 3-pronged, cable box 2-pronged, tape decks 2-pronged.  These are spread across three power strips from outlets on two walls, and I don't as of yet have any power management or line conditioning devices.

I had the same issue when I added my Behringer amp to power my subs.  I went as far as making sure all 3 of my 20 amp outlets in the room were on the same leg of the breaker box.  Still no help.  I went to Wal-Mart and bought a 3 prong to 2 prong adapter for 50 cents.  Worked like a charm.  No hum at all.
 

Incredible!  Because someone on the phone just told me the same damned thing.  I'll get some tomorrow and try it.  I'd go out right now, but I've spent the whole day running around, and I've got a fabulous new TV screen to swoon over.  Thanks -- I'll report back tomorrow.

Interrupting the ground may stop the hum, but it may also stop your ground wire from protecting you & your equipment. I had a ground loop issue and bought one of these:

http://www.amazon.com/Ebtech-Hum-Voltage-Filter/dp/B0002E4YI8/ref=pd_bxgy_MI_img_b

No more hum for 3 years now.

I'll have to look at that closer.  Will it work on a 20 am outlet?

I know I'm taking a chance with that adapter but it was quick and easy.

You'd use one of those for each 3-prong plug, in place of the 3-to-2 adapters?

Yes, they are designed to eliminate hum caused by the ground plug without removing the benefits of that 3rd plug.  But $65 compared to 50 cents makes you think about how many you will need.

Yes I am using mine on a 20A plug. In all honesty, I don't know how much the ground wire actually is used, but $65 is much cheaper that replacing my equipment. I had the loop in between my SVS, Receiver, Equalizer, and Projector. I only had to interrupt it in one place. I believe I put the HumX on the projector only.

Quote:

Originally Posted by Robert_J 

I'll have to look at that closer.  Will it work on a 20 am outlet?

 

I know I'm taking a chance with that adapter but it was quick and easy.

Well, I just applied the 50-cent solution (actually, they were 63 cents at Home Depot today) to the two front speaker amps, and VOILA!  It's a miracle!  No hum at all, though I'll check tonight in the quiet of evening for any stray noise that isn't evident over the neighbor's leaf blower.

I didn't put one on the phono pre-amp, and apparently don't have to.  So now, on top of everything else, I'm back in vinyl heaven again.  Thank you both.

If you spill any liquid on the floor, don't touch your equipment while you foot is in it.

Well the more I thought about this...... The ground wire IS being used to some extent as proven by the presence of the hum. By using a 3-2 adapter you are breaking the loop, but you are also not giving the "stray electrons" a place to safely go. In the least case, electronics do not like static discharges. Robert_J hinted to worst case.

 

I have no problem going to the $65 device (or two of them) as long as I know that it will fix the hum problem and, for certain, restore a basic level of safety.

By the way, these two amps are plugged into a power strip.  Not the typical el cheapo, but nothing terribly exotic either.  Is it going to be okay to plug those two filters into that as well?  Is it better (safer) if they're put directly into outlets?

I am not an expert, but I wouldn't think it matters.