amplifier hum

Gene E. Jones · Post by **Gene E. Jones** » 15 Dec 2005 4:09 pm

I have a nashville 400 amp and a mci d-10 steel. IF i flip the ground switch to the negative [down] then i have much less hum, way worse if the switch is positive or neutral. Can i do something to make it hum less? If you are on stage is the hum much of a problem? In general i do not think i have ever been bothered with it when i am playing in a band, but just if I am practicing at home. suggestions?thanks, gene

Jack Stoner · Post by **Jack Stoner** » 15 Dec 2005 4:12 pm

Does it hum with nothing plugged into it? or does it only do it with something plugged in?

If it does it with nothing plugged in, turn the reverb off (to zero) and see if still hums. If that fixes it, most likely there is a bad connection in the "molex" connector for the reverb that plugs into the chassis. Many times just unplugging that connector and then plugging it back in will "clean" the contacts.

If it's not the reverb then it may be bad power supplyu filter capacitors and a trip to the shop is needed (or better yet shipped to Peavey for repair).

If the hum is external to the amp, it could be a cable, it could be the pickups if they are not hum buckers, etc.

Ray Montee (RIP) · Post by **Ray Montee (RIP)** » 15 Dec 2005 5:33 pm

Excessive VOLUME on the amp along with too much presence and loads of volume on the guitar can produce a similar affect. Sometimes with feet on a cement floor or dampened wooden deck floating on a small lake in Kelso, Washington, can cause a similar affect as well as playing on the steel decking and gally benches on an ocean going Hawaiian tugboat name "O-NO" in the Columbia River.

Jeff Hyman · Post by **Jeff Hyman** » 16 Dec 2005 2:55 pm

http://www.monstercable.com/pro_audio...

This got rid of any and all problems I was having to date.<font size="1" color="#8e236b"><p align="center">[This message was edited by b0b on 16 December 2005 at 03:07 PM.]</p></FONT>

b0b · Post by **b0b** » 16 Dec 2005 3:08 pm

Moved to "Electronics" section of the Forum.

Steve Hackney · Post by **Steve Hackney** » 16 Dec 2005 7:15 pm

Gene
This may or may not apply to your situation at home, but I had the same problem. Turned out to be the flourescent lights in my garage where I practice. I killed the flourescents and the hum went away.

Steve

Curt Langston · Post by **Curt Langston** » 16 Dec 2005 7:38 pm

Gene, A friend of mine has an MCI with a stock Barcus Berry pickup. That baby hums! I think the Barcus pickup is a single coil, of lesser quality than a TrueTone. IMHO.

Jack Stoner · Post by **Jack Stoner** » 17 Dec 2005 3:37 am

All these suggestions are good, but the FIRST thing is to determine where the hum is. Is it in the amp or is it "external" to the amp. Until that is determined you can't logically troubleshoot the problem, all you are doing is guessing.

I am speaking as a former amp tech, the "shotgun" approach to troubleshooting really isn't the way to go.

Gene E. Jones · Post by **Gene E. Jones** » 17 Dec 2005 2:22 pm

Thanks to all for your help on this issue. As i began to investigate I got lucky this time. The amplifier did not hum with nothing plugged in. When i changed from number one to number 2 amplifier jack the hum stopped.thanks,gene