Ground loop hum nonsense

[jr_spyder]

Warning - this is kind of a rant.

I just installed a nice shiny new JL Audio F113 sub in my family room (thanks Ivan!). It replaced a monstrous Klipsch sub that I've had for years. Ohhhh, it's so much better, but that's no surprise.

When unplugging the old sub and removing the dusty cheater adapter from the power cord I was really hoping I wasn't going to have put it on the big fat JL stock cord, especially since I'm using a balanced input from my pre now, replacing the unbalanced cable the Klipsch used. Also, this tag on the JL cord sounds ominous:



To my great disappointment all my speakers throughout the system had a ground loop hum as soon as the connections were made. The JL sub can even be powered off and I still get the hum. Naturally the cheater adapter was then employed and the hum went away.

I'm not looking for any explanations here. I've fought this battle for years like everyone else has. I get it. I understand it. I also know people have tried to follow every rule including rewiring their houses and it didn't work.

When I look at the back of my highly regarded Bryston BIT20 power conditioner I see many cheater adapters on almost every power cord, and certainly all the amps. Really?

But why does the ground loop issue still exist? This is all top end gear from long standing manufactures and yet none of them can figure out how to internally eliminate the ever-so-likely ground loop problem? And JL (and maybe others) has the audacity to tell you not to remove the ground pin?

I just don't get it. Luckily the solution is quite simple with the cheater, but wouldn't it be better it all our gear was properly grounded?

Rant off. I feel better, I love my system, and I'm quite sure I won't be getting electrocuted.

Cheat away,

John

[redm]

Does it still occur if you pipe the electric through AC regenerators?

[jr_spyder]

Haven't tried just because it's a little too far away for the stock cord, and I'm not hopeful. Nonetheless I'll try it with a simple three-wire extension cord just as a test for the hum. That being said I don't want to plug this (delightfully) power sucking amp into the same source/circuit as the rest of my gear. I also don't want to invest in a standalone power conditioner for a sub. I plan to put one of those noise reducing outlets in the wall where I plug in the amp, but that's it for conditioning, and that won't fix the ground loop. Maybe I'll sneak and not connect the ground wire to the back of the outlet so I don't need the cheater on the front! (joking of course)

[jdandy]

John.......Ground loop issues are not caused by your audio components, It's not a manufacturing issue that can be solved with some power supply change, short of not grounding components at all. There's no reason to blame the gear or the manufacturers for electrical deficiencies in your homes circuitry or an issue that may be caused by an improperly grounded video component such as the notorious cable box with DC injected on the coaxial cable that feeds a signal to it. I would not be the least bit surprised to discover the issue is coming from a video cable box or satellite box that is then connected to your preamp or processor. You may want to try installing a cable TV ground loop isolator like the one from Viewsonics. Install it with a short coaxial jumper to your cable TV boxes that have audio or HDMI cables connected from it to your audio gear, even if it's to the TV first before a connection to your audio gear. This may solve the ground loop issue.

One way to trouble shoot this problem is to remove the incoming cable company coaxial cable or satellite coaxial cable from you video boxes. If your ground loop hum disappears then you have found the culprit. Install the Viewsonics ground loop isolator on the incoming coaxial cable and you should be good after that.




http://www.amazon.com/Viewsonics-VSI...+loop+isolator

[jr_spyder]

Thanks Dan, but I solved that issue a long time ago and routinely use a TV coax isolators in my systems. Sure enough without it I get hum.

I guess the part that surprises me the most is that all my gear in this system, except the sub, plugs into the Bryston BIT20, which plugs into a dedicated 20amp circuit. I would think/hope all the outlets on the conditioner would have the best chance at not creating any ground loops in the power lines of the components, and no DC noise if that's an issue. Nonetheless my two MC2301's, MC205 and some other gear need their grounds lifted or else I get hum. I can't say I'm blaming the manufactures on my bad wiring or whatever the cause, but I've got to believe this is solvable at a component level but the expensive stuff we all own doesn't do it.

I know I'm not alone in this and I'm not picking on Bryston by any means. People get this problem no mater their conditioner, as I have with other products in the past.

I'm curious - do you have any cheaters on any of your power cords? If not what's your secret? It seems every home theater I've ever seen has cheaters liberally deployed.

John

[jdandy]

Originally Posted by jr_spyder

I'm curious - do you have any cheaters on any of your power cords? If not what's your secret? It seems every home theater I've ever seen has cheaters liberally deployed.

John.......I do not have any cheater plugs on any of three separate systems that include two separate audio systems and one 5.1 home theater system. I guess my secret was being an electrical contractor and wiring my own home, studio and home theater. I know everything is 100% correct from panels to outlets. All three systems are on dedicated circuits. Each system's circuits share the same phase and the same cable length runs back to the panel. The studio system and the HT system are fed from a subpanel with the dedicated circuits for each system, all on the same phase. All three systems are silent. It is something that requires attention at the installation point. Once a structure is closed up and finished it is difficult to determine what was done behind the walls and whether or not every electrical connection was terminated properly.

[GaryProtein]

Originally Posted by jdandy

John.......Ground loop issues are not caused by your audio components, It's not a manufacturing issue that can be solved with some power supply change, short of not grounding components at all. There's no reason to blame the gear or the manufacturers for electrical deficiencies in your homes circuitry or an issue that may be caused by an improperly grounded video component such as the notorious cable box with DC injected on the coaxial cable that feeds a signal to it. I would not be the least bit surprised to discover the issue is coming from a video cable box or satellite box that is then connected to your preamp or processor. You may want to try installing a cable TV ground loop isolator like the one from Viewsonics. Install it with a short coaxial jumper to your cable TV boxes that have audio or HDMI cables connected from it to your audio gear, even if it's to the TV first before a connection to your audio gear. This may solve the ground loop issue.

One way to trouble shoot this problem is to remove the incoming cable company coaxial cable or satellite coaxial cable from you video boxes. If your ground loop hum disappears then you have found the culprit. Install the Viewsonics ground loop isolator on the incoming coaxial cable and you should be good after that.




Amazon.com: Viewsonics VSIS-EU Cable TV Ground Loop Isolator: Electronics

Does ONE of these on the incoming cable to the house solve the problem or do you need one of these going to every cable box and component?

[jdandy]

Gary.......I would assume that a single ground loop isolator installed where the cable first enters the home before any distribution would be sufficient.

[GaryProtein]

Thank you!

I purchased TWO a while ago when you recommended them but haven't connected them yet.

What am I going to do with the second one!?!?

[jdandy]

Gary.......Until you are positive the isolator is working for your particular issue I would keep both. You may have to install them directly behind each cable box in question. If a single one works for everything downstream then become a benevolent benefactor and give the other isolator to someone in need or throw it in the junk drawer in the kitchen.