Bass amp noise(hum) in mains ?

[Hotrodmick]

I use a small Ampeg, 115, that hums through the mains when not playing. It doesn't always do this. The last bass player had the same problems with his rig. This happens a lot when we are doing set up and everything is on also.

Just a thought, I'm not an electrician but could this be dirty electricity ? I do use the line out on the amp and it doesn't happen all the time. If it is the power, can I get something to plug in to?

I hope this make sense and thanks.

 

[s0c9]

Sizeof the amp is not relevant.
If it hums when powered, it's likely a ground loop.. If it happens at one venue and not at others, it's NOT likely dirty power but how the building is ground wired.
If you plug into one circuit and the PA is in another.. the hum can be REALLY bad if both circuits are hooked to different grounds. Often, the venue is running refrigerators or other "noisy" devices on the same circuit you plugged into.

DO NOT USE ground lift devices to remove the hum, especially when using a tube amp.
Power will go to ground when something breaks, and lifting the ground means it will likely go thru you.. you probably won't survive that!

Try different outlets.. and try to make sure you and PA are on same circuit,

 

[RustyAxe]

Sounds like a ground loop. We run all our gear on one 20A circuit through a Furman 20A power conditioner.

 

[Zooberwerx]

Read this: Hum going to FOH

Even a compromised XLR mic cable can introduce hum. Start with the easy stuff and work your way up.

Riis

 

[Hotrodmick]

Thanks. I must of missed that thread.

I unplugged the direct input and guess what, the hum went away. I'm going to try using a mic on the amp and see what happens, then the cable, or vice versa.

As always, you know it's the bass players fault. ;-)

 

[RustyAxe]

I've gone nuts trying to find a hum, only to find that there was an unconnected cable laying on the floor, but connected to the PA. Never leave a cable hanging with nothing connected to it.

 

[s0c9]

I unplugged the direct input and guess what, the hum went away. I'm going to try using a mic on the amp and see what happens, then the cable, or vice versa.

That's a ground loop... check that your bass and PA are on same circuit and see if that fixes it.. I sometimes have this issue at one venue we play at.. I move the power supply to another outlet, and it will go away.

 

[Zooberwerx]

Thanks. I must of missed that thread.

I unplugged the direct input and guess what, the hum went away. I'm going to try using a mic on the amp and see what happens, then the cable, or vice versa.

As always, you know it's the bass players fault. ;-)

You're on the right track. Couple of steps that may pinpoint the culprit...not all-inclusive, mind you:

*Try another known-to-be-good XLR cable.

*Run your bass straight into a DI > mixer, no other peripheral devices. If the hum is gone, add the devices one-by-one (before the DI!) and see if the hum re-appears. Add the amp last.

*If you're absolutely certain the amp is the source and the suggestions provided so far (thanks, guys!) don't remedy the situation, consider snagging the isolation and lift devices cited in the linked thread above.

Riis

 

[Maddmaxx1]

I'm having the same problem and I know it's the lights, but they are needed, I'm going to try changing the power location and see if that helps there's a Furman power conditioner that the mains are hooked up to I'll try that. Both my Fender Jazz basses are caged and active one has a Audere jz3 the other has a J retro

 

[s0c9]

I'm having the same problem and I know it's the lights, but they are needed, I'm going to try changing the power location and see if that helps there's a Furman power conditioner that the mains are hooked up to I'll try that. Both my Fender Jazz basses are caged and active one has a Audere jz3 the other has a J retro

The gear used is not relevant.. it's power related.. try changing out the XLR cable, then power source.. hum is ground loops.

 

[Jules Meuffels]

In my experience, lights (especially dimmer switches) are the problem 9/10 times, when in the same circuit. In occasion a badly placed amp transformer can cause a hum, when tilted 90 degrees, hum's gone.