Wall outlet hum

[Patrick Huey]

I have a NV 400 and a Session 500 and play strictly at home. The house we live in now is an older one and both amps when plugged into the wall have a noticeable hum. Can anything be done to eliminate this? Thanks!

[Donny Hinson]

First things first...you need to buy an outlet tester, and that will tell you if the problem is in the house wiring. About $6 at Home Depot or Harbor Freight.

[Paul Arntson]

I agree the first thing you need to do is use one of those testers.

Another thing you can try is to turn (absolutely) everything else in the house off (including AC units and refrigerators) and see if the hum is gone. If it is, then turn things on one at a time and see when it comes back. This is kind of a radical procedure, but it will find whether it is coming from something in the house. Plus it doesn't cost anything to check.

Other more rare things can cause it, too. Let's see what you find before we go into those.

Also, you didn't say whether the amps themselves hum or whether the hum only comes on when the guitar is plugged in. This would help. Also, whether the pickups are single coil or humbuckers.

[Tony Prior]

several years back I went to a guys house to buy an amp he was selling. It had all sorts of AC hum. It was a brand new house.

I was gonna walk from the amp but he was insistent on me buying it, he dropped the price to a point where i just said..oh what the heck, so I bought it. It was a Marshal JCM 900/50 watter with a 4x12 cab.

I dragged it home, about an hour away, plugged it in to check it out and... ( drum roll please)

Uhhh.,.it was silent. I called the guy to let him know , left a message , but never heard from him again.

Moral to the story

CHECK THE HOUSE WIRING ! Check other rooms as well.

[Michael Maddex]

What Donny and Paul said. Also, try rotating the amp(s) with relation to the wall to see if there are any louder or quieter orientations. Good Luck.

[Craig A Davidson]

I live under a highline and anything I have with single coils hums. My Sho-Bud is one example as it has single coils. But when I am gigging with it the guitar is quiet as a mouse.

[Joey Ace]

All good advice.
Also check if any light dimmers are in use.

[Lee Baucum]

First things first...you need to buy an outlet tester, and that will tell you if the problem is in the house wiring. About $6 at Home Depot or Harbor Freight.

Everyone should carry one of these devices and test all the stage outlets at each venue before plugging in gear. I keep one in my pac-a-seat.

[Michael Mirabal]

Patrick, one of this issues with old homes is grounding. You might have a receptacle with a ground out but it might not be hooked up to anything. And, your panel might not be bonded to a ground or water pipe. There are a lot of devices out there, some cheap and some expensive that will eliminate the hum. A good one, for about $80 is Ebtech Hum X. If you have electrical problems, it wont fix them but at least it will eliminate the hum.

[Danny Harrell]

I carry an Ebtech Hum-X hum eliminator. They are expensive, but you can catch them on sale at times. It helps with the hum especially electrical hum. They are 3 prong inlet plug and 3 plug into wall socket.

[Al Evans]

Everyone should carry one of these devices and test all the stage outlets at each venue before plugging in gear. I keep one in my pac-a-seat.

This deserves repeating/ A buddy of mine blew up a rather expensive PA amp some years back, plugging it into an outlet that was wired sideways. I'm pretty sure he carries a tester with him nowadays.

--Al Evans

[Michael Hartz]

If you have any soldering skills at all you can make your own Ebtech hum eliminators. it's just qty.2 6A -1KV power diodes reversed with each other (parallel) soldered together with a 1k 1/2 watt resistor soldered across the whole thing. Then this whole thing gets soldered between the ground on your outlets and the green ground wire on your cord. Then electrical tape everything up and stick it in your outlet box. You can get the power diodes off ebay, thats what I did. This is exactly what a $90 Hum X is, nothing more-nothing less. 60 cycle hum that we hear is actually about 4volts. The power diodes wired in parallel filter out any voltages below 4.7 volts but still allow electricity to flow to ground if the hot were to ever short to ground. All the resistor is for is to show continuity if you were to check the outlet with a tester otherwise without it the circuit would show an open ground ( which it's not). I got under $20 wrapped up in building one. I’ve built several gang box electrical cords this way and they work amazing.

[Erv Niehaus]

Try plugging the two amps into two different circuits in your house and see if that helps.
Erv

[Bobby D. Jones]

I would suggest check voltage in outlet too. If the pole supply transformer has a short it may be supplying over 120 Volts which will cause lots of problems.

[Lee Baucum]

Are you running your guitar through both amps at the same time? That can cause a ground loop / hum.

[Greg Cutshaw]

https://www.youtube.com/watch?v=CuvDMjxhE68

Video of hum eliminator without the RF bypass capacitor. I would think that at least 35 amp high thermal mass diode should be adequate. The resistor never sees much voltage or current so it can be low wattage. There are other hum elimination devices that eliminate hum from sources other than the all outlet and you may need one of these instead:

https://www.amazon.com/EBTECH-HE-2-Ebte ... words=humx

[George Redmon]

The EBTECH's are pricey but boy are they worth it. They have a nice round one out that i leave connected on my Furman strip. A life saver. Sometimes you can git lucky and land a nice used one.

[Clyde Mattocks]

Several years ago I bought a Peavey Session 400 for 100.00 because it hummed. I knew I could come out on it by either sending it back to Peavey or troubleshooting it myself. I opened it up and with a plastic pen started moving wires around. I quickly found that by simply rerouting a couple of wires it quieted right down. I fastened the bundle in place with a plastic tie and its been good ever since. Usually hums in Peaveys are a fairly simply fix unless its filter caps.

[Murray McDowall]

Hi Michael,
If you could show us a simple diagram, that would be much appreciated.
We have 240v mains here in Aust., so I guess double the value of the resistor (2k ohms) would be about right?
Many thanks & regards,
Murray.

[Michael Hartz]

The first time we played at a particular casino, they didn’t have a 220v outlet to plug our distro in so we had to plug our PA and amps into various outlets along the stage. This caused a loud hum in the PA that we couldn’t get rid of. Before the next time we played there I made several of these hum free outlet boxes and made sure nothing was plugged into their outlets that didn’t go through these hum free outlet boxes first. Everything was dead quiet after that, no hum whatsoever. Made a believer out of me then on. I’ve probably made 10 to 12 of these since then. By the way the gentleman on the forum I found this on said he took a part a Hum X and carefully cut away all the goop covering the circuit ( manufacturer doesn’t want you to see how simple it is) and this is what he found.

[Robert Leaman]

Before you go for any of the mentioned play toys, you must check the ground system for the house wiring. Some one mentioned a pole transformer short. If you have a poor or non-existent wiring system ground, you have a potential accident waiting to happen. A badly grounded house system wiring in New Jersey nearly caused the death of a family.

A wiring system ground on the secondary side of the pole transformer is there to protect against high voltage entering a home. If the pole transformer has a primary to secondary short, the ground house wiring system will cause the pole transformer primary fuse to blow thus opening the high voltage supply. This is the real reason to have a grounded neutral wiring system in a home.

The neutral must be connected to good earth ground system. If you are served by a municipal water supply, you have means to properly ground your system. The ground bond must connected on the incoming side of the water meter. If is not possible to be connected on the incoming side, then the meter must be by passed with a good wiring bond that is connected from the incoming side around the meter and then bonded to the meter outlet side.

If there is not a municipal water supply, then a good ground can be obtained with solid copper rod driven into the earth at building's exterior. Sometimes, a small amount of copper sulfate is put into the bottom of the small hole that is produced by the rod. This chemical attracts water and increases conductivity for the ground rod.

Please be safe and check this before you go for any the afore mentioned devices.

[Steve Sycamore]

Don't the proper Ebtech devices have a transformer inside? I have several and they generally work very well. Maybe I'll try taking one apart if they aren't riveted (which is quite possible).

[Murray McDowall]

Many thanks Michael!
I'll give it a try.
Regards,
Murray.

[Stefan Robertson]

isn't that why "hum-bucker" pickups were invented? to solve the single coil hum.

Change your pickup.