Makeshift rig - buzzing

[guit5iddle]

Hi there, this is my first post, top of the morning to you all

I'll get to the point; I'm running a Strat into a Boss GT-5, and then out of the left and right channels (all using standard 1/4" cables) into a Fender Blues Jr. and a Peavey Vegas 400. Whenever the Vegas is plugged into the board while the Blues Jr. is on, however, I'm getting a noticable buzzing noise (from both amps) that isn't affected by volume level, gain level, or seemingly even whether the Vegas is powered on or not.

I've spoken to a couple of people, and it was their view that it has something to do with the polarity of the speakers, i.e., the Blues Jr's speaker has a different polarity than the Vegas 400's speaker (I think that's what they said), but is there anything I can do to fix it?

Thanks for reading, be happy, be healthy, sing a song

[defaced]

Sounds like a possible ground loop. Test this by removing the plug from the vegas or the GT-5 and touching the outside of the plug or the sleeve to the chassis. If you hear the buzz, you have a ground loop.

[brandonnys]

I agree

Yep, sounds like a ground loop. You could put a ground loop isolator in your interconnects and that should get rid of that hum. You can get them online, or even at radio shack, I'm sure.

I built an inline isolator transformer with the help of this guy online, and it helped me get rid of some loop issues: Audio line isolation transformer

I'd try that.

[guit5iddle]

Sounds like a possible ground loop. Test this by removing the plug from the vegas or the GT-5 and touching the outside of the plug or the sleeve to the chassis. If you hear the buzz, you have a ground loop.

Gosh. I'm not really a techie...sorry...um...

The "plug" is the power cord that plugs into the surge protector?
What is the "sleeve?"
I know what a "chassis" is, but I'm not certain what part of the amplifier is the "chassis" or which amplifier's "chassis" you mean for me to test...

I do appreciate you getting back with me about this so quickly, and I apologize again for being a noob

[brandonnys]

You have Interconnect cables (1/4" cables that connect your GT-5 to each of the amps).

If you take the interconnect cable between the Vegas and the GT-5 and unplug it from the GT-5, just touch the sleeve of the plug (marked with an S in the image below) to the chassis of the GT-5. If the Vegas makes a hum, that's a ground loop.



** Note: The image shows a stereo plug. Yours is probably a MONO 1/4" plug, meaning the R isn't going to be there. Your just going to have a T (TIP) and an S (SLEEVE).

[defaced]

No worries. The plug I'm talking about is the phone plug (guitar cord plug): TRS connector - Wikipedia, the free encyclopedia (yours probably won't have a ring connector). The sleeve is diagrammed in that link.

With everything hooked up and buzzing sound coming out of the speakers, do the following:

1) Unplug the guitar cord from the Vegas. It will probably go nearly silent
2) Touch the sleeve of the guitar cord to some bare metal part of the amp's chassis (no paint or anything to inhibit conductivity - if the chassis is chromed, that's fine). If your guitar has a metal cover like most do, it is connected to the sleeve so that will work as well. I'm not familiar with that amp, so I don't know where would be a good place to do this at. If it buzzes, you have a ground loop.
3) OPTIONAL: If there is no place that is bare metal, plug a second guitar cord into the input of the Vegas, and touch the sleeve of the cord coming out of the GT-5 to the cord of the Vegas. This will likely be less effective because the amp's input will be "open" and probably noisy which might cover up the buzz you're looking for.

[guit5iddle]

Okay, ground loop confirmed, ty for being patient

My next question is, most of the ground loop isolators I saw in a google image search were coaxial or rca...are you guys saying they make them for 1/4" cables?

[brandonnys]

I made one or two back in the day, but now I use the CleanBox II. It works really well. Here's a link: ART CleanBOX II | Sweetwater.com

[guit5iddle]

Cool beans, tangerines

Thanks guys for all your help!