Amp buzz conundrum

There is a Guild punch line to this question, but it's a sound system issue and I'm hoping one of the many techies here may have a quick answer. I've attached a (rough) drawing of my home studio. Apologies that some lines are power and some are signal and I don't differentiate, but hopefully it's obvious what's what. My Tone King MK II Imperial amp has a loud buzz, 60 Hz I assume. My Fender Princeton '65 reissue amp does not. The buzz disappears if I'm holding the guitar and touch a vocal mic at the same time. All devices are on the same Furman "power conditioning" power strip. If I unplug everything on the circuit breaker and only plug in the amp, the buzz exists. The Tone King buzzes to a varying degree with all my guitars except my Guild X-500, which is dead quiet. Thanks in advance for any suggestions.

Hi

There are no visible ground loops - but since everything needs to be grounded - I'd say the TK-amp seems to be not !!!!!

When you touch the microphone - then YOU BECOME THE GROUND WIRE !!!!!

Does the amp have a 3-prong power-cable? And wall outlet ground is ok??


Things to check otherwise.

If you and the other guitarist switch sides - bringing your leads with you - does the buzz stay on TK ? If yes - then it is really something wrong with that amps grounding - and better have it checked before it gets fatal.

Hi Nuuska,

Thanks for taking the time to look at this. That all makes sense. The amp has a 3-prong cable. I've also tried changing the amp power cord. I've moved the amp to various outlets and there is always a buzz. Touching either mic, when the amp is plugged into the system power strip, kills the buzz. When I first created the studio, I had components on multiple outlets and I got zapped holding a guitar and touching a mic at the same time. Putting everything on a power strip solved that problem, but the TK amp has always had a slight buzz which recently got worse. I only recently noticed that touching the mic kills the buzz. The amp has also started making a popping noise on start up.

The piece I don't understand is why my X-500 is dead quiet in the TK amp.

Anyway, I will stop using it and get it checked. Thanks again so much.

Modern equipment should never zap you. Either your amps got problems or your house wiring does.

Vintage amps can shock you and should always be upgraded to 3-prong plugs.

Longnose Gar said:

The amp has a 3-prong cable.

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GAD said:

Vintage amps can shock you and should always be upgraded to 3-prong plugs.

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Is this just a restatement of generic, and good advice, or is there something about the amp in question that I missed.

"Your amp should never have more of a buzz than you do." , said an an old music gear seller way back when...

fronobulax said:

Is this just a restatement of generic, and good advice, or is there something about the amp in question that I missed.

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This amp is not vintage. It's two years old and came with a 3-prong.

Now I'm stumped on this again as I plugged in a different amp and got the exact same behavior. Then I scrutinized my seemingly quiet Fender amp, and it's doing the same thing to a lesser volume. I'm going to get the multimeter out and poke around. Maybe I just have a really noisy power supply and an effective RC filter is created when I touch the mic or plug in the X-500.

Longnose Gar said:

This amp is not vintage. It's two years old and came with a 3-prong.

Now I'm stumped on this again as I plugged in a different amp and got the exact same behavior. Then I scrutinized my seemingly quiet Fender amp, and it's doing the same thing to a lesser volume. I'm going to get the multimeter out and poke around. Maybe I just have a really noisy power supply and an effective RC filter is created when I touch the mic or plug in the X-500.

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Never assume an outlet is properly wired. Outlet checkers are cheap and available at your favorite big box hardware store.

fronobulax said:

Is this just a restatement of generic, and good advice, or is there something about the amp in question that I missed.

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Probably just general good advice Nobody wants to suffer the fate of Les Harvey, guitarist with Stone The Crows

GAD said:

Never assume an outlet is properly wired. Outlet checkers are cheap and available at your favorite big box hardware store.

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Good tip. I will get one. I know I at least have ground loop problems across outlets that I should fix.

I think I've made sense of the buzz now, and the amp is normal. I found this page helpful. I noticed that turning off lights reduces the buzz. Holding the guitar increases buzz (added capacitance between guitar and wiring), but touching the strings or mic reduces/eliminates buzz (grounding the body and creating a Faraday shield). I guess in the end this is all studio 101 stuff I'm just figuring out now because the buzz was getting bad. Thanks everyone for your help.

Did you check switching amps AND cords ?

Next - try that amp with another guitar.


BUT - on post #3 you write : " When I first created the studio, I had components on multiple outlets and I got zapped holding a guitar and touching a mic at the same time. "

THAT sounds like some serious problem - apologies for not noticing it at first reading.

My daughter complained of getting shocked in her room while playing guitar. I went in to check it out and the problem was an interesting one: While holding the guitar and playing along with her iphone, she'd get a shock when she pushed the button on her phone. I got the outlet tester out and discovered that the outlet she had her phone plugged into had a ground fault, so when she held the guitar that was connected to an amp in a different outlet that was on a different circuit, then pushed the physical button on her iphone, she because the ground path between the two circuits. Not cool!

The scary part is that we re-sheetrocked the entire room so I had access to all the outlets and they're all wired perfectly. I even replaced all the outlets and there's still a ground fault on that side. I then traced the other outlets on that circuit in different rooms and they all have a ground fault - a ground fault that I cannot find. We're likely moving in the next year so I'll have an electrician figure it out, but for right now I've put childproof caps in all of those outlets as a reminder to not use them or to ask me first if whatever's being plugged in is OK.

GAD: did you check for a loose ground connection on that circuit, at the breaker panel?

Nuuska said:

Did you check switching amps AND cords ?

Next - try that amp with another guitar.

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Yep, those were the first things, hoping for an easy answer! The fact that my X-500 was the only guitar that had zero buzz helped me figure out this is all EMF interference. So if we want another reason to praise the X-500, it appears to have excellent shielding. On the other hand, my 1999 FMIC X-170 is the worst offender

BUT - on post #3 you write : " When I first created the studio, I had components on multiple outlets and I got zapped holding a guitar and touching a mic at the same time. "

THAT sounds like some serious problem - apologies for not noticing it at first reading.

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Indeed, and I bypassed that problem by putting all equipment on a single outlet. But now I'm reminded I need to get it fixed.

geoguy said:

GAD: did you check for a loose ground connection on that circuit, at the breaker panel?

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Not yet. I'm not afraid of electricity, but I tend to leave the panel to the people with licenses.

Longnose Gar said:

Yep, those were the first things, hoping for an easy answer! The fact that my X-500 was the only guitar that had zero buzz helped me figure out this is all EMF interference. So if we want another reason to praise the X-500, it appears to have excellent shielding. On the other hand, my 1999 FMIC X-170 is the worst offender

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I'd be very surprised if the X500 had any shielding. If this is an outlet problem it's it's ground not EMF. If it's a ground problem the X500 could be clean because it's not properly grounded.

When the guitar hums does it get better or worse when you touch the strings?

Also, just because it’s a fairly new amp, don’t assume the fault is in the outlet(s). It could be a cold or broken solder joint in the amps ground wire. You said you tried changing cords, so I assume it has an IEC power cord jack. I’d start looking at that and make sure the grounding is good, with nice shiny solder.

GAD said:

I'd be very surprised if the X500 had any shielding. If this is an outlet problem it's it's ground not EMF. If it's a ground problem the X500 could be clean because it's not properly grounded.

When the guitar hums does it get better or worse when you touch the strings?

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Better if I touch the strings. Better if I touch the mic. I also plugged the sound system (amps, mixer, mics, etc) into an outlet on a different circuit from the lights in the room. When I turn on the LED lights in the room, the buzz increases 3X. This happens whether the sound system is on the same circuit as the lights or a different circuit. All this behavior seems consistent with EMF, per this article, but I could be missing something.....

AcornHouse said:

Also, just because it’s a fairly new amp, don’t assume the fault is in the outlet(s). It could be a cold or broken solder joint in the amps ground wire. You said you tried changing cords, so I assume it has an IEC power cord jack. I’d start looking at that and make sure the grounding is good, with nice shiny solder.

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I'm getting the same buzz behavior on 3 different amps. I removed the original amp of concern and plugged in a different amp and got the same behavior. The other amp I have on the circuit also buzzes, but at a lesser volume. This makes me think it's not the amp.

If you've got a floating ground then when you touch the strings you become the ground. If you also happen to be touching something with a proper earth ground then you become the path to earth and that's when things get frightening. That's what happened to my daughter in the above post.

A combination of multiple grounding problems can make everything more difficult to figure out. For example if your LED lights are on the same circuit as your guitar amp and there's a floating ground, then you could be hearing buzz from the lights that isn't EMF if the path to ground decides to have something to do with your amp.

Ground loops can be small (within a guitar) or huge (entire rooms or more) and can be a royal PITA to resolve. If your X500 is the only properly wired guitar then that could explain why it's not picking up EMF, while the others do. You may have EMF *and* ground problems.

AcornHouse is correct in that a bad solder joint could be causing your issue as could 100 other things which is why these problems can be maddening, especially with a bunch of know-it-alls trying to diagnose it over a forum.