Amp troubleshooting

[ougrad02]

I am using an onkyo 705 receiver and using the preouts to connect the front three channels to three outlaw monoblocks. Just got done hooking it up and when I turn the amps on I get a loud humming/buzzing noise from the speakers. The actual sound from whatever I am listening to is there but quieter than the hum. Any ideas?

 

[Adam]

Might be a ground loop issue.

Try disconnecting all of the inputs from the amps (after unplugging the amp power cords), but keep the speakers connected. Then, power the amps up and see if you get a buzz or hum. You could even try them one at a time, seeing as how they are monoblocks. If you get a buzz/hum without anything connected to the amps except for the speakers, then you know that it's not your inputs that are causing it. Be sure to double-check your speaker wire connections, too.

Please let us know the results of that.

Once you get it set up and don't have this issue, I'd appreciate reading your opinions of the Outlaw monoblocks. I've looked at those myself. Thanks.

 

[ougrad02]

Ok I tried some unplugging and the buzz/hum stops when I disconnect the coaxial cable from my cable box. I researched that a bit I found I may need a ground loop isolator? However all the ones I can find seem to use rca type cables instead of the coaxial like my cable line.

 

[Adam]

Cool, at least now you know the source of the problem.

I recommend checking out this article from Audioholics on ground loops and how to fix them. They describe a cable TV ground isolator that seems to be what you'd want.

Others here know a lot more about ground loops than I do, and hopefully they'll chime in. I haven't ever run into a problem with one.

 

[ougrad02]

I will check that one out thanks. Anyone know where I could pick up a cable tv ground loop isolator locally instead of online?

 

[Adam]

From my web searching, I haven't seen one at a major chain, yet. If you have any local stores that sell TV antennas, you could give them a call to see if they carry any. Also, your cable provider might have them, and they might even install one as part of your service contract - certainly wouldn't hurt to ask them!

 

[ougrad02]

Alright I'll try those ideas and if all else fails order one. I don't mind ordering, was just hoping to get it up and running today! ha ha. Anyway I will let you know what I think of the monoblocks once they are up and running. Thanks for the help.

 

[Adam]

Something else that I would try, if you haven't already, is a surge protector/power conditioner that has coax cable inputs and outputs. I honestly don't know if it would work, but one of those might tie the coax lines to the same ground as the power outlets - and that might just get rid of your ground loop problem.

You can get those in a wide range of prices, but I've seen them start at around $30.

 

[ougrad02]

Adam,

I tried your suggestion of the surge protector and it worked like a charm. once I have everything running I let you know what I think. Thanks.

 

[Adam]

Fantastic!!! It's always great to find a quick, inexpensive (hopefully it was) solution. Sorry that approach didn't come to mind sooner.

Did you get the 2200 model with their free shipping offer on a purchase of three? I almost bought that last year, but I didn't want to use up three outlets.

 

[ougrad02]

No I was actually able to find a deal on ebay on some 4 monoblocks. I was going to get an extra and run them on all five channels but decided to just use 3 for the mains and center. I'm actually going to sell the extra one.

 

[tdamocles]

I will check that one out thanks. Anyone know where I could pick up a cable tv ground loop isolator locally instead of online?

Not sure about locally but this will solve the problem (Holland isolator).

Adam,

I tried your suggestion of the surge protector and it worked like a charm. once I have everything running I let you know what I think. Thanks.

Do you have Comcast On Demand?

 

[mtrycrafts]

I will check that one out thanks. Anyone know where I could pick up a cable tv ground loop isolator locally instead of online?

If your video cable TV line from the cable box uses the screw type F connector, Radio Shack should have an F type to RCA in one connector. You need two such adaptors and that isolator you found.
Or, if RS doesn't have it in stock, perhaps a local electronics parts store?

 

[ougrad02]

Tdamocles,

Yes I have comcast on demand. Why do you ask?

 

[tdamocles]

Tdamocles,

Yes I have comcast on demand. Why do you ask?

Which surge protector with coax f type connectors did you use? I have a Monster surge protector (HTS2000) which I could not get my On-Demand to work with.

 

[ougrad02]

Hmm I haven't tried the on-demand yet so I will check that out later. Thanks for the heads up.

 

[ougrad02]

Nope the on demand isn't working. I'll get one of the transformers and try it.

 

[tdamocles]

Nope the on demand isn't working. I'll get one of the transformers and try it.

The isolator that I recommended works like a charm......

 

[ougrad02]

I have actually ordered and tried both the jensen and the holland cable isolators. Both of them get rid of the hum but both of them cause some of my hd channels not to work. So I guess I have to try something else.

 

[ougrad02]

Figured it out.