Buzzz goes the gainclone(ground loop)

[AJ Bertelson]

I moved into a new house a couple of weeks ago. Finally got the chance to hook the gainclone up(briangt design) to the HTPC again. At my old house the gainclone worked perfectly with the HTPC.

Hooked all of my equipment up and turn on the gainclone and I am treated to a nice buzz. Just to make certain nothing had happened to the amp I tried a portable radio hooked up the gain and didn't get any buzz.

I have plugged the power cord into different outlets but haven't had any luck.

any more advice?

[carlosfm]

Do you have more than one device earthed?

[BrianDonegan]

Also, are your outlets properly grounded (grounded at all)? May be worth a test.

[AJ Bertelson]

Originally posted by WorkingAtHome
Also, are your outlets properly grounded (grounded at all)? May be worth a test.

this is something that I was starting to wonder also. They are the standard 3 prong outlet. How do I go about checking to see if they are properly grounded?

[homer09]

Originally posted by AJ Bertelson
this is something that I was starting to wonder also. They are the standard 3 prong outlet. How do I go about checking to see if they are properly grounded?

hmmm, i guess one way of testing if the grounds are not just floating is checking with a DMM. set it to 150VAC or more, shove one probe in the hot, one prob in the cold. you should get something near 120VAC. then just move the prob from cold to ground, and you should get the same reading. (hot is the right hole when facing a plug) if your ground isnt grounded, you wont get 120VAC.

careful though, these are high voltages!

[carlosfm]

Originally posted by carlosfm
Do you have more than one device earthed?

AJ Bertelson,

My question was if on your system there's more than one device with a ground connection.
It's important to know this.

[BrianDonegan]

I agree with Carlos, as his point is more likely to cause a problem. The outlet ground is still important, but much less so. Relative ground is more likely the problem (most components don't have a mains ground).

The most reliable (safest) way to test is to use an outlet tester (available from home depot, etc). Plug it in to your outlet and indicator lights tell you what is wrong, or if everything is okay.

Search on "GFI-501A" onthe HopeDepot.com page. You are looking for the Gardner Bender GFCI Circuit Tester Model GFI-501A. Under $8.

[carlosfm]

What I mean is that if there are two components with a "safety" earth connection, there will be a ground loop.
Take for instance a preamp and a power amp, both earthed.
There will be a ground loop, noise will be very noticeable.
Because there will not be one single ground connection between the two devices, as it should be.
Ground will return to the preamp by two different paths: the interconnects AND the earth wire on the electrical system.

I'll stay by here before I go to Texas for "safety" reasons.

[chris ma]

Originally posted by carlosfm
What I mean is that if there are two components with a "safety" earth connection, there will be a ground loop.
Take for instance a preamp and a power amp, both earthed.
There will be a ground loop, noise will be very noticeable.
Because there will not be one single ground connection between the two devices, as it should be.
Ground will return to the preamp by two different paths: the interconnects AND the earth wire on the electrical system.

I'll stay by here before I go to Texas for "safety" reasons.

Yes! when using true mono block the ground loop goes from either left power amp thru the speaker to the right power amp thru the speaker and back or left power amp thru the preamp to the right power amp and back

even thru the wall ground to complete a loop via the amps

[AJ Bertelson]

well I picked up the tool and it said that all outlets were wired correctly.

wonderfull, where do I go from here?