So I finally got the 990 and 7500 and all my speakers and all my cables hooked up and ready to go!!! I get all the inputs set to go and turn the amp on for the first time. What do I hear?

THE DREADED GROUND LOOP HUM!!!!

I remember the 7500 manual having something about that. It says try unhooking the cable first. So I try that. Sure enough the hum is GONE. Thanks for the troubleshooting guude outlaw. Damn Cable.

I keep reading and the manual says I will need to insert a ground loop isolater. What is that? Can I do it myself? I also just got off the phone with the cable company and we tried just about every setting in the cable box. The hum got quieter but was still there. I'm having them send someone out.

There are isolators that you can buy from Radio Shack or Parts Express for about $15 or less (the Dayton from Parts Express is probably the most often recommended), and you can easily connect it yourself. The cable company would provide the same sort of device when/if they send someone out - or they might fix the ground connection on your cable service, of course.

There's also the Jensen VRD-1FF, which costs a bit more (around $60) but is probably one of the best around.

Ground loops can be a little deflating when you've got all that new gear just ready to sing. I can recommend the Jensen since I use it to eliminate a ground loop caused by my cable. The RS or PE models may work equally well for less money. Even better get the cable company to come out to your house and correct the problem.

Enjoy your system!

Good recommendation Gonk. I picked up a ground loop and had to put one of these in my system. Not only did it get rid of my hum, it improved the picture to my TV. I highly recommend this devise.

BTW, my system was free from hum and then one day it just started? No equipment changes, etc.

This is only my second post in the Saloon (Star Trek-like “Non-interference” doctrine at Outlaw). However I wanted to comment on the “dreaded ground loop hum”.

I too encountered the problem and at first, purchased an inexpensive ground loop isolator. While the hum was totally eliminated, I encountered countless digital freeze-ups of the picture on my HD cable box. In addition, the "music on demand" channels were unusable due to constant and lengthy drop-outs.

Scott recommended that I give the Jensen solution a try. I visited their site and after reading their technical data I recognized that ground loop elimination is one of their core competencies. I purchased the VR-1FF nearly a year ago. Like the inexpensive transformer it totally eliminated the hum. However, the digital freeze-ups were also completely eliminated by the Jensen piece.

My particular set of circumstances was pretty severe and while more expensive than most of the other transformers, the Jensen solution totally cleaned up my problem.

Are there other products that would have done the job? I am sure that some are out there. But in my case, I did not have the time for a lengthy science experiment. The Jensen piece removed a lot of frustration in my home and that means a lot (especially when my wife was watching Lost and the picture froze). Like anything else however-YMMV. Just my two cents.

Peter

My Comcast cable hum was cured from outside the house when I had my first HD cable box installed a few years ago. Twenty plus years prior the cable had been run from the pole drop into my house uninterrupted. The installer ran a new drop to a ground block which then ran into the house. He attached the ground block wire to the nearby service panel conduit.

That was a good day, HD and hum-free in one fell swoop.

Peter,

I guess nobody clued in to who you are!

So let me beat them all to it and say screw the Star Trek policy. Drop in more frequently and share your wealth of experience and wisdom with us.

No need to engage in debates on the merits of your products, but topics such as this one are fair game.

Hey, if you can't pee in your own sandbox...

Jeff,

I'll bite. Who is PeterT?

Bug

PeterT is Peter Tribeman.

Who's Peter Tribeman? Peter Tribeman is Outlaw's president.

Well then!!!!

PeterT, please drop in any time. You may not have much time for us, but we forum members do appreciate your comments and advice.

I also have a problem with a "ground loop hum" since adding the 7500. It seems from many of the posts I've read, the Jensen Transformer has been successful in the case of those who have Cable systems. I have DirectTV and when I tried the Jensen Transformer (VRD-1FF) it simply cut off the signal altogether...obvioulsy not compatible with Satellite bandwidths. Any suggestions for a similar device that works with Satellite feeds?

The cable guy came out and looked very confused when I explained the problem to him. So I brought out the manual and read it word for word highlighting the solutions provided in the manual. He still didn't seem to know what to do. He asked if I had any video problems and I said no. He said putting in a ground loop isolator usually fixes video problems but he had never heard my problem before. I suggested he try the isolator for this problem too. He didn't seem like he really wanted to do it but did it anyway. Lo and behold the problem is fixed. He still looks dumbfounded. I explain to him that it's probably the same issue that causes the video and audio problems.

I sometimes wonder about the techincians. Atleast my problem is fixed.

congrats getting your problem fixed. While the cable guys are pretty knowledgeable about cable hook ups.. they often lack a real electronics background.