Pickup hum

[bcbrian]

Has anyone solved pickup hum on a Kramer 450B or any other Kramers with humbucker pickups? When I point the neck in the same direction that the amp and cabs are facing, all is quiet even with the gain elevated but when I rotate the guitar 90 degrees, too much hum. It's similar to a feedback. Has anyone had success shielding with copper or aluminum tape? My 450B has an aluminum base plate in the cavity already but that's it for shielding. The farther I play from the system, the hum decreases. Basically, the more gain the more hum. It doesn't seem to be a ground loop problem.

Thanks for any effort to respond.

From bcbrian in British Columbia Canada.

 

[RSBBass]

Does it matter where you are playing? Shielding helps with 60 cycle and RF hum. These tend to vary with location.

That said, shielding is hard to mess up to the point where you make things worse.

One last thought, is the aluminum plate grounded?

 

[bcbrian]

My first reply on this forum, thanks! The hum is quite audible within a 10 foot radius of the system but fades out farther away. Again, the hum comes and goes with 90 degree rotations of the guitar and yes, the control cavity base plate is grounded. I tried using a Hum X made by Ebtech but to no avail.

 

[uOpt]

The hum is 50/60 Hz cycle hum, right?

If it is strongly directional it is almost certainly magnetic interference and you can't use shielding to fight it.

Question is, why does your humbucking not work?

 

[Audere]

Max both volumes and Tones.
Does it happen equally with each pickup soloed and with both pickups on?

Does the bass have original Schaller pickups?
These were normally in a series wiring and had relatively good cancellation.

If your amp is outputting a VERY large amount of magnetic field hum or overtones then you might be getting cancellation but just not enough.

 

[bcbrian]

Okay, thanks guys!
I'm not familiar enough with humming to say that it's a 60 cycle hum but it seems like it is. It's a familiar sounding hum that I've heard in the past, so probably. I maxed out the knobs, tried the pickups as suggested and still getting the hum. The pickups are the originals. They're Mighty Mites single humbucks. I'm running an Eden WT550 amp that's fairly new and never gigged.
I'm sure impressed with this forum.

 

[Audere]

Maybe I am out confused this bass is from pre 1980 correct?
I thought a Kramer 450B had Schallers in it...

Anyone know if Mighty Mites are this old?

I also expected a Les Paul type switch with settings of Bridge, Both, Neck pickups.
If the noise is the same in all positions then the pickups must be humbucking and the magnetic field is still larger than your pickups can cancel.

If you are sure it gets less as you move in a circle from your amp.
Then the amp or something close to it is probably the noise source.
Check to make sure their are no wall warts etc. plugged in behind the amp.
Move the amp setup to a different location using a different wall plug.
If you still have a problem and the same circular noise pattern as you move away from the amp then the most logical answer is still the amp.

David

 

[mellowinman]

So many people never think of the obvious reasons pickups hum.

They don't know the words.

 

[Low Commotion]

Does this happen all the time (everywhere you play)? The reason I ask is that when I have the guys over to my place, I get hum from my P-bass when I stand about 10' from the power panel. I can have the hum increase/decrease as I turn 90 deg. We now practice in the other room.

 

[bcbrian]

Okay! I finally found the source of the interference. I live in a large log house and the living room is 20'X30' with a vaulted ceiling with two light fixtures about 15' above the system that have three spiral fluorescent bulbs each. I shut off the fixtures and the hum is gone. Now I'll have to figure out what lighting to use. My girlfriend has LED's throughout her house and one of the bulbs in her bathroom screws up some TV channels. I think the next step is get up there, unscrew the bulbs, turn on the switch and see if i get the interference back... Maybe candle power...?
To answer the questions asked, the model of Kramer I have is around 1978/79. The switch is a 3 position. Electrical fields....what can I say. I guess the next step is to contact the high end electrical boyz. I want to add that my Kramer has Pyramid Gold strings, a Hipshot brass bridge and is run through Eden/DNA cab system and the sound is beauuutiful. My many thanks to all of you for showing your interest.

From Brian in Beautiful British Columbia.

 

[Audere]

The good news is you found it.

You should check for an external ballast before plugging other types of lights in.
Try nothing in the sockets.
Then try regular light bulbs. Regular bulbs will be a resistive load and the least likely thing to cause extra noise assuming your wiring is correct.
Well assuming you do not go for solar or candle power...

Most current fluorescents use a high frequency switching design which improves the efficiency and reduces the size/weight/costs.
For example, my electronic bench lights work at 75 KHz +/- 10% depending on the bench.
There is some lower frequency noise emitted but not a lot.

 

[bcbrian]

I wasn't accurate when I said that I had two overhead "light fixtures". Actually, the "fixtures" are ceiling fans with three light sockets each. Okay, there's a fan motor up there. I have two wall switches, one for the fan and the other for the lights. I don't have hum with the lights off and don't get hum when the fan is running, but perhaps the fact that there's a motor up there when the lights are on maybe creates some kind of magnetic field? I may have to take the fan down and replace it with just a fixture? Well, getting closer to resolving this. Who knows, maybe down the road this thread will help others with interference problems. Thanks for continuing on Audere.