Mystery amp problem

[gitplyr]

I own two amps. One is a Kendrick Texas Crude and the other a 52 Fender Pro. Both have always worked perfectly in my home. Recently, both developed a loud hum when the guitar cable is plugged in whether or not the cable is plugged into a guitar. They both work perfectly at the shop that does my repair work. The hum shows A# on my strobe tuner. I thought I had a 60 cycle hum so I purchased a Tripp Lite conditioner/isolator. No improvement. I called a licensed electrician who checked my service panel, outlets, etc. and found no issues. The last test he did was to isolate my amp from every circuit in the house. Still hummed. He then bypassed my meter in a way where it was as if my amp were plugged directly into the power company transformer that serves my home. Still hummed. He thought there must be a grounding issue in the transformer or the line from the transformer to my house. The power company came out and pulled my meter, replaced it with a testing device and assured me the voltage and drop were perfect. He said that also proved there were no grounding issues at the transformer or between the transformer and my home. My home is grounded with a grounding rod and secondary ground to the plumbing. A friend loaned me a Furman PM PRo. It shows I have proper voltage, grounding, etc.. It does not improve the hum. One other curious issue is that when I have the Kendrick on stand by the light sometimes does not light up. It only lights up when I take it off stand by. This never happens when I take the amp to my shop. My cables are all good cables in good repair. The problem happens at all outlets in my home. Any thoughts??

[Ngr]

if power supply is good then it must be some EM field. are you near a power plant or an industry? did recently major changes happened in your neighborhood (new buildings, new companies or similar)? it seems that your guitar cable is picking a strong EM interference.

Originally Posted by gitplyr

I own two amps. One is a Kendrick Texas Crude and the other a 52 Fender Pro. Both have always worked perfectly in my home. Recently, both developed a loud hum when the guitar cable is plugged in whether or not the cable is plugged into a guitar. They both work perfectly at the shop that does my repair work. The hum shows A# on my strobe tuner. I thought I had a 60 cycle hum so I purchased a Tripp Lite conditioner/isolator. No improvement. I called a licensed electrician who checked my service panel, outlets, etc. and found no issues. The last test he did was to isolate my amp from every circuit in the house. Still hummed. He then bypassed my meter in a way where it was as if my amp were plugged directly into the power company transformer that serves my home. Still hummed. He thought there must be a grounding issue in the transformer or the line from the transformer to my house. The power company came out and pulled my meter, replaced it with a testing device and assured me the voltage and drop were perfect. He said that also proved there were no grounding issues at the transformer or between the transformer and my home. My home is grounded with a grounding rod and secondary ground to the plumbing. A friend loaned me a Furman PM PRo. It shows I have proper voltage, grounding, etc.. It does not improve the hum. One other curious issue is that when I have the Kendrick on stand by the light sometimes does not light up. It only lights up when I take it off stand by. This never happens when I take the amp to my shop. My cables are all good cables in good repair. The problem happens at all outlets in my home. Any thoughts??

[kafka]

Get an EMF meter or one of those clamp-on ammeters. Shut off all power to your house at your master breaker, and then measure the current running through your water main. You won't see zero, but anything over residual levels indicates a problem with the neutral at one of your neighbor's houses. If the problem is with the neutral from the transformer, you might be able to get the power company to do something about it. In my case, the power company replaced the underground power cabling to my house and every house on the block. If the problem is inside of one of your neighbors' houses, you'll have to find a way to track down whose problem it is. This can be hard to do because everybody on the block will show similar symptoms. If you're lucky, you'll find someone had some work done recently that is causing the problem. You'll then have to communicate to them that this is a dangerous situation that needs to be corrected.

[tyguy335]

Originally Posted by gitplyr

I own two amps. One is a Kendrick Texas Crude and the other a 52 Fender Pro. Both have always worked perfectly in my home. Recently, both developed a loud hum when the guitar cable is plugged in whether or not the cable is plugged into a guitar. They both work perfectly at the shop that does my repair work. The hum shows A# on my strobe tuner. I thought I had a 60 cycle hum so I purchased a Tripp Lite conditioner/isolator. No improvement. I called a licensed electrician who checked my service panel, outlets, etc. and found no issues. The last test he did was to isolate my amp from every circuit in the house. Still hummed. He then bypassed my meter in a way where it was as if my amp were plugged directly into the power company transformer that serves my home. Still hummed. He thought there must be a grounding issue in the transformer or the line from the transformer to my house. The power company came out and pulled my meter, replaced it with a testing device and assured me the voltage and drop were perfect. He said that also proved there were no grounding issues at the transformer or between the transformer and my home. My home is grounded with a grounding rod and secondary ground to the plumbing. A friend loaned me a Furman PM PRo. It shows I have proper voltage, grounding, etc.. It does not improve the hum. One other curious issue is that when I have the Kendrick on stand by the light sometimes does not light up. It only lights up when I take it off stand by. This never happens when I take the amp to my shop. My cables are all good cables in good repair. The problem happens at all outlets in my home. Any thoughts??

Move!

[gitplyr]

I sincerely appreciate the feedback. One of my neighbors did have to call the power company out to his home about the same time my problems started. In his case, his lights were working in part of his home but not others while none of his heavy appliances were working. The power company subcontractor replaced his junction but claimed to have a problem locating his transformer. I believe he would be on the same transformer as me.

[kafka]

Originally Posted by gitplyr

I sincerely appreciate the feedback. One of my neighbors did have to call the power company out to his home about the same time my problems started. In his case, his lights were working in part of his home but not others while none of his heavy appliances were working. The power company subcontractor replaced his junction but claimed to have a problem locating his transformer. I believe he would be on the same transformer as me.

Bingo. That's the one. His return current is going through his ground (i.e. the water main), through your water main, and returning to the transformer via your neutral. The correct path for the return current to the transformer would be via his own neutral. Ground is only a safety measure should there be a fault with the neutral. Otherwise, ground shouldn't generally be conducting. Electricity spreads out in all directions in a circuit, so there will always be some current on the water main. However, it should only be a residual amount.

The hum comes from the fact that that the circuit is unbalanced. All conducting circuits produce a magnetic field. However, if the hot and neutral are close together, then the field from the two conductors almost totally cancels itself out. The one place where hot and return aren't in the same package is the ground, and only when ground has become a path because the neutral has a fault.

[drbob1]

Stupid question: you have tried a different, high quality guitar cable and a different guitar to make sure it's not an input problem, right?

[nedorama]

Loud hum could also be filter caps - on a '52 Fender, it's way past due for filter caps to be replaced. Keep the originals in a baggie for those purists. On your Kendrick, may be worth checking.

As a simple check, get an eBtech HumX which is an isolated power transformer - Tripplite makes good stuff, but unclear if your product has isolated power transformers - you need to decouple it. I have 1 at home and 1 in my gig bag. Great for bad power houses, bars, etc.

[gitplyr]

In reply to the latest two replies. Yes, I have tried different guitars and my cable is a new Klotz. I would have assumed a cable or input issue as well if it were not that the amps, cables and my guitars work perfectly at other locations. My amps are both in perfect working order. The 52 Fender was totally overhauled recently as well as the Kendrick and both work perfectly elsewhere. The Tripp Lite is one with a Faraday shield. Their representative said the unit would not solve a ground loop issue if there were a grounding issue in the home. My electrician verified there are no ground problems, primary or secondary, in my home. The Tripp Lite also didn't work when my home power was cut off and my electrician hooked my amp in direct line with the power company transformer that serves my home. That is why the power company is trying to trace any issues in the line back to the transformer and the transformer itself. I also tried a Furman PM Pro that was loaned to me. The power company sent another more specialized team out yesterday. They are supposed to be back with me today.

[nedorama]

At least that's ruled out. wish I could help more. The Ebtech is designed specifically for ground hum. We have the same issue at my house - my Bandmaster will hum at home, not anywhere else. With a HumX on the outlet, it's as quiet as can be.

Worth $60.

[gitplyr]

I'm going to get the HumX and try it if the power company has no answers. It won't hurt to have one around anyway at the price.

[gitplyr]

Excuse me..Ebtech

[teleharmonium]

A secondary ground could be causing a ground loop. Can you disconnect it (the one on the plumbing system) and test ?

Other common culprits are dimmers on lights.

[gitplyr]

The Hum X didn't work either. I'm still waiting to hear back from the power company. I ordered an EM meter to see if my plumbing could have an abnormal current traveling to my home from a neighbor with a possible loose neutral. I may have to call an exorcist!