|
Post by stratosphere on Mar 17, 2008 22:14:13 GMT -7
What are the most common causes of increased 60hz hum, just from the amp with volume all the way down, no guitar plugged in?
I have an 65 fender doing this not my Z. I swapped out preamp tubes, but nothing changed. It does this through a power conditioner or straight into the wall. Could something need to be replaced other than the tubes?
Thanks
|
|
|
Post by dixiechicken on Mar 18, 2008 0:25:32 GMT -7
DC here!
Can be several things:
1) Bad wiring in your house or on the stage. 2) Light dimmers on the same power group as your amp-juice. 3) Grounding loops in the amp 4) Grounding loops in your house. 5) The shielding in your amp has been been broken for some reason at some point.
Cheers: Dixiechicken!
|
|
|
Post by benttop (Steve) on Mar 18, 2008 5:40:30 GMT -7
You might want to have a tech look it over because bad filter caps can also give you some hum.
|
|
|
Post by Lefty on Mar 18, 2008 7:11:00 GMT -7
+1 caps
|
|
|
Post by Phil (aka Phil) on Mar 18, 2008 7:14:13 GMT -7
If it's a '65 Fender I'd bet it's the Philter caps too
|
|
|
Post by stratosphere on Mar 18, 2008 18:09:03 GMT -7
Thanks guys, I took it to an amp tech today. He echoed the cap theory.
|
|
|
Post by Curt on Mar 18, 2008 20:08:44 GMT -7
Just found this thread, but Caps wuz my first reaction too. BTW, '65 Fender what? Luv 'em here !
|
|
|
Post by myles on Mar 18, 2008 20:10:36 GMT -7
You might want to have a tech look it over because bad filter caps can also give you some hum. You bet on the caps, especially with their age in his amp. Mismatched output tubes will do this too and if one is dead it will be worse than bad caps.
|
|
|
Post by stratosphere on Mar 20, 2008 18:44:01 GMT -7
Ok, here's where it gets weird. My Maz started making noises nasty distorted sounds when playing, crackling kind of sounds and then more hum then usual and the hum increases as the volume is increased. Turn the volume all the way down and the hum goes away. The kind of sounds I would expect from a bad filter cap. I changed the tubes but it's still there. Two amps in one week. Ouch!
|
|
|
Post by benttop (Steve) on Mar 20, 2008 18:47:40 GMT -7
That's interesting, but hum that goes away when you turn the volume down seems to indicate something in the preamp, like maybe a bad tube or maybe a bad guitar cord. Does it do it with the guitar unplugged?
|
|
|
Post by stratosphere on Mar 20, 2008 21:24:56 GMT -7
Thanks Benttop, It was a tube I had just replaced in the reverb circuit a short time ago that was the culprit. It went microphonic. Boy, never assume... I had another post a little while ago about going through alot of 12at7's in the same spot. They all went microphonic in a relatively short time. First i thought it was just bad luck, but it 's too much of a coincidence. Myles had recommended I take it to a tech and I'm going to do just that.
|
|
|
Post by benttop (Steve) on Mar 20, 2008 21:55:25 GMT -7
Sounds like good advice from Myles, as usual.
|
|