mystery amp problem

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gitplyr
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mystery amp problem

Post by gitplyr » December 10th, 2011, 8:23 am

I'm having an amp problem and was wondering if anyone here would have any helpful input. I own two tube amps. One is a Kendrick Texas Crude and the other a 52 Fender Pro. Both have always worked quietly in my home. Recently both developed a loud hum when you plug in the guitar cable whether or not it is plugged into the guitar. The hum intensifies if you hold the guitar end plug against your body. I guessed it was a problem with my Monster cables and purchased new Klotz cables. No improvement. The hum shows a B flat on my strobe tuner so I then guessed it was a 60 cycle hum. I bought a Tripp Lite power conditioner/isolator with a Faraday shield. No improvement. I talked to Tripp Lite who said I must have a bad home ground. A licensed electrician checked out my home and found nothing. He isolated my amp from everything in my home with a test cable attached to my breaker box. Still hummed. He then pulled my meter and hooked the test cable in a way was as if my amp was hooked directly to the transformer that serves my home. Still hummed. He said there had to be a ground problem in the transformer or in the line between the transformer and my service entry. Power company came out, pulled my meter, replaced it with a meter like testing device, took their readings and said I had proper voltage and drop. I asked if that proved there was no grounding problem in the transformer or lines and he assured me that was the case. My amps both work perfectly at the shop that does my repair work. Any ideas?? The electricians did check my sockets the main ground rod connection, secondary ground to plumbing, etc.. The problem happens no matter where in my home I hook up.
Last edited by gitplyr on December 10th, 2011, 10:20 am, edited 1 time in total.

greybeard
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Re: mystery amp problem

Post by greybeard » December 10th, 2011, 10:03 am

It sounds to me as if everything has been tested, but your home earthing connections. It's all very well checking what happens at the entry point to your house, without checking what happens between entry point and consumption point (i.e. wall socket).
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gitplyr
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Re: mystery amp problem

Post by gitplyr » December 10th, 2011, 10:06 am

The electrician did check my outlets, the service panel itself, the primary ground rod as well as the secondary ground to the plumbing. The hum is there no matter where I hook up within my home.

Blue Jay
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Re: mystery amp problem

Post by Blue Jay » December 12th, 2011, 7:09 pm

That's weird, but I think it still may be a problem in the transformer that serves the house. I assume the amps worked well before, and then this hum thing just arose. And the amps still work good at a different service location? Blame the source.
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kent_eh
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Re: mystery amp problem

Post by kent_eh » December 13th, 2011, 5:29 pm

Have you tried taking the amp(s) to a friend's house or some other location?
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gitplyr
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Re: mystery amp problem

Post by gitplyr » December 14th, 2011, 7:52 am

The power company sent a more specialized team out yesterday. They didn't have an immediate answer but took some readings with their equipment at my meter, junction box in the front yard and at the transformer itself. They are to get back with me today. I would think the issue has to be somewhere in the power company lines or at the transformer. The electricians who checked my home completely shut off the power to my home, ran a heavy cable from the meter leads directly to my amp through a bedroom window. It was as if I were plugged into the transformer with only the power company buried cables and my junction box between the amp and the transformer. The hum still happened even with the Tripp Lite in line. The Tripp Lite would have corrected the hum unless there were a bad ground so it sure points to the transformer. The amps, my various guitars and cables all work perfectly at friends homes and my repair shop. We also tried a Furman PM Pro that my shop loaned me with no improvement. All update the thread after my power company gets with me today.

s1120
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Re: mystery amp problem

Post by s1120 » December 14th, 2011, 8:43 am

kent_eh wrote:Have you tried taking the amp(s) to a friend's house or some other location?
Or plugging diferent guitars, and cables into it?
Paul B

gitplyr
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Re: mystery amp problem

Post by gitplyr » December 15th, 2011, 3:23 pm

Yes, the amps, my guitar and cables all work perfectly at friends houses and at the shop that does my repair work.

gitplyr
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Re: mystery amp problem

Post by gitplyr » December 15th, 2011, 6:19 pm

yes..both amps, my cables and my various guitars work perfectly at the shop that does my repair work and at a friend's home.

kent_eh
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Re: mystery amp problem

Post by kent_eh » December 15th, 2011, 6:33 pm

I suppose another possibility might be that something nearby is generating an EM field, though it would have to be pretty substantial to have an effect at any great distance.

Is your neighbour running a welder, or a bunch of neon signs, or something odd like that?
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s1120
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Re: mystery amp problem

Post by s1120 » December 16th, 2011, 2:43 am

kent_eh wrote:I suppose another possibility might be that something nearby is generating an EM field, though it would have to be pretty substantial to have an effect at any great distance.

Is your neighbour running a welder, or a bunch of neon signs, or something odd like that?

Ya, thats my guess also. Neon signs, a lot of floresent lamps?? Maybe try killing the circit your plugged into, and plugging in somewere else in the house. that will see if its something on the same circit. Has it always done it or is it new?? What was added, or changed to the house before it started?
Paul B

gitplyr
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Re: mystery amp problem

Post by gitplyr » December 16th, 2011, 7:28 am

I've visited with my immediate neighbors and none have anything going on out of the ordinary. The amps hum no matter where I hook up in the house. The only commercial activity going on in the area is the laying of fiber optic cable several blocks from me. We have no new appliances that would account for the change in the amp behavior. The amps both worked perfectly in my home until a month ago and both still work perfectly anywhere but here.

kent_eh
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Re: mystery amp problem

Post by kent_eh » December 16th, 2011, 10:41 am

Hmmm, I'm stumped.

Any UFO landing areas nearby? :lol:
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greybeard
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Re: mystery amp problem

Post by greybeard » December 16th, 2011, 2:51 pm

I'd be interested to hear the results of encasing the amp in a faraday cage.

If you have some fine mesh chicken wire, you could create a faraday cage, which would not totally eradicate external emissions, but would noticeably reduce them.

If it made no difference, the disturbance is coming via the mains circuitry and not via such things as transformers or neon signs.
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kent_eh
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Re: mystery amp problem

Post by kent_eh » December 16th, 2011, 7:09 pm

greybeard wrote:I'd be interested to hear the results of encasing the amp in a faraday cage.

If you have some fine mesh chicken wire, you could create a faraday cage, which would not totally eradicate external emissions, but would noticeably reduce them.
I'd recommend metal windows screen, rather than trying to find chicken wire in a urban area. Plus the mesh is finer, and you can more easily buy reasonable sized pieces.
I wrapped a newspaper ’round my head
So I looked like I was deep

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