new sub problem

[nats]

I had a strong hum from my new sub. After much trial i found it was coming from the cable tv, Doesnt matter if its on or off. It stops if i unhook it from the wall or if i un hook the hdmi. It was the same with diffrent cables-swapped boxes ect... For the 1st time ever i hooked the cable into a power conditioner and the humming stopped. My question is am i now just hiding a problem or is this the proper design solution of the conditioner?

 

[Towen7]

Classic ground loop issue. It's not dangerous. The outer shield of the cable line is supposed to be grounded. The electrical inputs to your components are also grounded. What's going on is that the outer shield of the cable tv line has a different electrical potential than the others. It common and what you've done to solve the hum is sufficient.

 

[Flint]

Towen7 is 100% correct - it is a common ground loop (very, very common). That's one way to solve the problem, and if it works, you are all set.

Another way, if that method is inconsistent or insufficient, is to buy a specialty product to specifically lift eh ground between the cable line and the cable box. I use one solution from Jensen transformers.

http://www.audioxpress.com/bksprods/products/pj-vrd1ff.htm

 

[MatthewB]

Rat Shack also sells an inexpensive groud loop isolator that I use on my sub.

 

[Flint]

Rat Shack also sells an inexpensive groud loop isolator that I use on my sub.

That may solve the subwoofer hum, but it does not address the root problem of a ground loop issue from the cable TV line. If you don't address the root problem, then it can manifest itself in other areas like noise in the TV image, poor black levels, hiss and hum in the rest of the audio signal, and stronger thumps when switching inputs or turning on and off devices.

 

[Batman]

Flint do they make one that works on Sat signal? Still have that interference on my image over component distribution on secondary TVs in the basement...doesn't do it over HDMI...

 

[Flint]

Flint do they make one that works on Sat signal? Still have that interference on my image over component distribution on secondary TVs in the basement...doesn't do it over HDMI...

They do, but they are much more expensive since the satellite receiver has to power and communicate with the LMB.

 

[Batman]

Link? I can check Parts-Express too...

 

[Towen7]

If your problem is on the component output and not HDMI than it's more likely being caused by induction on the component cables and not the input from the LNB.

 

[Batman]

Depending on the price figured it'd be worth a try and I might get lucky so I don't have to pull 3 50+ foot hdmi cables...

 

[yromj]

Depending on the price figured it'd be worth a try and I might get lucky so I don't have to pull 3 50+ foot hdmi cables...

Just pull the HDMI cables already!! You know you're going to have to do it one day.

John

 

[Batman]

It's not the labor it's the $ since the TVs don't really get used but for 1-2 times per month unless there's a party, most people don't notice it. I will eventually pull the HDMI cables I'm just in no hurry. Then I'll need an hdmi splitter too...

 

[Towen7]

I have a monoprice 4x2 HDMI matrix switch that I'm not using.

 

[Batman]

That could be of some use, was it reliable when you used it? Any hiccups or handshake issues introduced by adding it to the chain?

 

[Towen7]

It was good, not perfect. Every now and then I'd have to turn it off or switch inputs to get it to sync up. But I left it on the same inputs 99% of the time so it didn't bit her me much.