[rydenfan]

Right now I am knee deep in chasing down a ground loop  It is driving me a bit insane. I temporarily threw a "cheater plug" on my amp and that has corrected the issue. I know that in theory all this plug is doing is breaking the ground. But I am curious what other member's thoughts on the subject are?

[Big Red Machine]

Eliminated or reduced?  I had a noise from an unshielded cable once.  Put in a shielded cable and problem solved.  Aren't you using a monster conditioner?  Or is the amp to the wall plug solo?

DO you know if the amp is on a different circuit than the other items?  That could be it.

[Wayner]

I run my amp and preamp on separate circuits and they are very happy. Ground loops are a bitch, but you have at least found the offender. If I may ASSume, your preamp has a 3 prong plug? Then with the amp connected to the preamp via interconnects, the amp is grounded through the interconnect shields. That's really the problem. your grounded twice and there is a difference to potential from the 2 points. If your preamp is grounded, you may want to reverse the condition and put the cheater plug on the preamp, and ground the amp. I only say that 'cause the amp has a larger fuse and a bigger load.

Wayner

[rydenfan]

They are on different dedicated lines but if I put them on the same line I still have the hum. The cheater plug has not completely eliminated the hum but it has significantly reduced it. I am going to rip the entire system apart tomorrow and plug every cable in one at a time and try and isolate it as best as possible. I do not plan on leaving the cheater plug on the amp. As a last case scenario I would rather shut down the breaker and remove the ground from the outlet and just float it.

BRM, Yes I use the big running springs conditioner but I have the amp directly to the wall.

[Wayner]

If you come to a conclusion that it is a loop between the amp and preamp and their interconnects, one trick used is to remove the shield on one end of both left and right interconnects, then you can plug both amp and preamp with their 3-prong plugs into the outlets with no adverse (and safer) operating condition.

Remember, the best grounding system is called a "star system". that is where all ground points come to one location. Sounds easy, but it's tuff to do. You are on the right approach, tear everything apart to the amp, preamp and speakers and see if you have hum at that basic level (which it sounds like you do), then add components and keep checking systematically one at a time.

Here is a fun bit of info. I had an FM tuner that made noise (hum) in my system simply by being plug into an outlet. It didn't even have to be on, or have the interconnects connected to the preamp, just plugged into the outlet wound do it. The damn thing is gone!

Good luck and keep us posted, help if we can.

Wayner

[rydenfan]

Thanks Wayne. It will be a real pain to tear everything down to the basics but I am the type who has to know what it is and not just put the cheater on and be done with it. I believe Cardas builds their IC's the way that you speak of for this exact reason. I may borrow a pair from a friend just to experiment further.

As a last result what do you think of shutting down the breaker for the line the amp is on, taking out the outlet, and removing the copper run to float that outlet?

[drab]

If I may respond, I don't think you would have a problem by removing the ground wire from
the receptacle, but the NEC requires ungrounded receptacles to be changed to GFCI's.

[Wayner]

Leave your house wiring alone and use the cheater plug. You don't have your equipment on wet concrete do you? I didn't think so...or do you?   Anyway, that's my suggestion, until you get to solve the mystery of the hum and get it totally nailed down. Step one, find the real problem. Step 2, find the real solution to the problem. Altering house wiring is not one of them (in my book).

Wayner  

[jeenie67]

1.)Make a solid connection to earth ground. This may be established if you don't have PROPER three wire connections inside the outlet box (you have to pull it from the wall and visually confirm proper black-hot, white-neutral, and bare-earth ground) or run a wire to the receptacle and wire it accordingly
 See   Rane: Grounding and Shielding Audio Devices and Sound System Shielding Audio Devices.
   online   PDf files at  <rane.com>  Rane note 151 and 110
These files will completely explain in depth the proper way to connect, trouble shoot, and prevent ground loops.   Jeenie67@gmail.com if any ?