Dave, can I get your feedback on this post?

randog · « **on:** 29 Mar 2006, 08:31 pm »

Hi Dave,

I posted this in the Odyssey forum but would be very interested in your feedback as well. Here is what I posted:

I have 2 Stratos. One that drives my left monitor and sub and one that drives my right monitor and sub. This is in an audio/HT system. When my preamp is on, I get a hum through the monitors... both of them have a similar hum through both the tweeters and drivers... again - they are hooked up to different amps.

I had the amps plugged directly into the walls, then plugged them into my BPT conditioner (along with all the other components)... same. I then bought a Monster HTS-3500II to get all my HT off the BPT and into the Monster and allow me to filter the satellite and phone cables... same. Today I unplugged the Monster which unplugs the TV, satellite, DVD, HT receiver, satellite feeds, phone feed... same.

I can hear the buzz from a couple feet away from the monitors.

1. Is this causing any harm to my tweeters and drivers? (Ellis 1801's)

2. What could be causing it?

3. Should I continue to seek out a solution or give up? You can't hear it under normal listening situations.

Thanks!
Randy

gitarretyp · « **Reply #1 on:** 29 Mar 2006, 09:14 pm »

You've probably already tried this, but working backwards from the amp is the best way to find ground loop problems in my experience.

Start with the amp hooked only to the speakers (ie, preamp and amp disconnected). If no hum, plug your preamp into your amp with no sources connected. If still no hum, plug each source in individually (ie, only have one source connected at a time). This way you can isolate which component is the culprit. If by chance it's a ground loop from cable tv, keep in mind several sources could be effected by the cable ground loop. Tv, vcr, dvd player, etc will all be affected because they will be sharing a common ground.

randog · « **Reply #2 on:** 29 Mar 2006, 10:17 pm »

gitarretyp,

Excellent ideas, thank you!

Randy

Al Garay · « **Reply #3 on:** 29 Mar 2006, 10:53 pm »

I recall having a similar problem biamping the 1801s. The source of my ground loop was the Comcast Cable.

randog · « **Reply #4 on:** 30 Mar 2006, 01:32 am »

Hi Al,

How did you fix that?

Randy

MemphisJim · « **Reply #5 on:** 30 Mar 2006, 03:38 am »

Sounds like a classic ground loop to me. These are very tough to work out. I had the same problem and cheated a little. I used one of those thingies that goes on the end of the power cord to lift the ground prong off of all equipment, and that solved the issue. I am NOT recommending that anyone do this, but it did work for me. I am lazy and haven't tried to work through the loop issue. I believe my issue stems from some of my equipment using plugs with a ground prong and some of my equipment using plugs without a ground prong.

Jim

Al Garay · « **Reply #6 on:** 30 Mar 2006, 05:26 am »

I had a spare TrippLite surge protector that had input and output for coax cable. I took the Comcast coax cable from the wall and plugged it into the surge protector input and ouptut going to the Comcast cable box or TV.

That was after having the Comcast technician out to make sure their cable was properly grounded.

By the way, do not plug your amplifiers into a Monster surge protector. I tried with my AKSAs and Hypex and killed their dynamics. I bought a BrickWall surge-filter to plug my sources, TV but not the amps.

randog · « **Reply #7 on:** 30 Mar 2006, 03:59 pm »

Thanks everyone. Al, I hear ya. I only bought that Monster for the stuff I'm not too finicky about... all my audio is on the BPT. I was hoping the Monster would help isolate the 75 ohm satellite cables.

Jim, thanks for the tip on the cheater plug. I have a copy of this post in the Odyssey forum and that was mentioned there as well... excellent way to troubleshoot. Thanks.

David Ellis · « **Reply #8 on:** 7 Apr 2006, 02:54 am »

Don't worry about any harm to your speakers. I believe the ground loop information above to be the causal factor. Or... maybe those amps just hummm a bit. This is certainly true with AC heaters in tube amps. At idle they make a little noise.

Dave

ooheadsoo · « **Reply #9 on:** 7 Apr 2006, 07:26 am »

I've got one of those amps and there is next to no hum at all with your ear 1 inch from the drivers. It's definitely from something else.

AKSA · « **Reply #10 on:** 12 Apr 2006, 11:26 am »

Randog,

If your amps hum, just give them the score; they've probably forgotten the words.......

Seriously, it's an earth loop, nothing more (or less

)

Cheers,

Hugh