Members inscho Posted March 24, 2006 Members Share Posted March 24, 2006 I bought a 67 bandmaster from crusty cabs a month and a half to 2 months ago. When the amp arrived I didn't have a speaker cabinet, so I went to guitar center to plug it into a marshall cab of theirs just to see if everything was fine. Completely quiet. Everything working fine. Finally I got my speaker cab yesterday, hooked everything up and turned on the amp. when I switched it off standby there was a fairly loud 60-80 cycle hum. I turned it off unplugged my cable, turned it back on same thing. There was also a cracking/sputtering noise that faded in and out. I tried different outlets in different rooms, different cable, tried all 3 positions of the ground switch, etc. Still no luck. Even when its on standby you can hear hum faintly When I bought the cab I was told that it had been fully serviced, and he is a very respected cab builder so I wouldn't think it was a cap issue. And it hasn't been played on or moved in about a month. I have changed out tubes and no luck there. Here is what steve/crusty emailed me saying: "When I serviced it, I replaced all the electrolytics in the amp. They're usually the only ones you want to replace, because they dry out after a certain amount of time, and they don't affect the tone of the amp. Replacing tone caps is generally done only when one has drifted way out of spec, as to cause abnormal operation, or gone belly up completely. The hum I'm not sure about. Could be a tube. The crackling definitely sounds like a tube, or maybe the plate load resistors. I can't remember now whether I changed them out or not. I don't remember what I sent out in that amp. I gave it a good workout before I boxed it up, and it performed fine for me." Steve any advice would be helpful. Link to comment Share on other sites More sharing options...
Members Sir H C Posted March 24, 2006 Members Share Posted March 24, 2006 Is it a 2 prong plug? If so try turning it the other way. Sometimes that will do it. Also be sure your house wiring is okay, again sometimes that can hose it. Otherwise, could be something got jostled around and that is what you are now hearing. Link to comment Share on other sites More sharing options...
Members inscho Posted March 24, 2006 Author Members Share Posted March 24, 2006 its has a 3 prong cable now. any idea what price I should expect from an amp tech to check it out/fix? I don't have anyone reliable, and I won't to avoid getting raped on tech fees. Link to comment Share on other sites More sharing options...
Members dave esmond Posted March 24, 2006 Members Share Posted March 24, 2006 First thing to do. Take the whole rig to a friends house. If no hum you know it's your house. Hum is many timenot the amp but the circuit it's plugged into. That's why it would sound fine at GC and the shop but not at your place. It's easy and cheap to check at least. After that the cracking might be a tube. I'd start there. Tap 'em lightly with the eraser end of pencil and see if one of 'em noisey. Good luck. d Link to comment Share on other sites More sharing options...
Members inscho Posted March 24, 2006 Author Members Share Posted March 24, 2006 Originally posted by dave esmond First thing to do. Take the whole rig to a friends house. If no hum you know it's your house. Hum is many timenot the amp but the circuit it's plugged into. That's why it would sound fine at GC and the shop but not at your place. It's easy and cheap to check at least. After that the cracking might be a tube. I'd start there. Tap 'em lightly with the eraser end of pencil and see if one of 'em noisey. Good luck. d I tried it at 2 different houses on 3 different outlet. no changeone of the 6l6's is microphonic, but I replaced them one at a time and this did not stop the noise.plus I hear the noise when its in standby, its faint but if I put my ear up to it, I can hear it.it sound like its coming from the area circled. Link to comment Share on other sites More sharing options...
Members dave esmond Posted March 24, 2006 Members Share Posted March 24, 2006 Oh. That sounds normal. Get your ear off there. :^) Can you hear it if you're a few feet away? Transformers always hum a little bit. So you can't expect 100% silence. The hum doesn't get louder when you turn up the volume does it? d Link to comment Share on other sites More sharing options...
Members inscho Posted March 24, 2006 Author Members Share Posted March 24, 2006 Originally posted by dave esmond Oh.That sounds normal. Get your ear off there. :^) Can you hear it if you're a few feet away?Transformers always hum a little bit. So you can't expect 100% silence. The hum doesn't get louder when you turn up the volume does it?d no its a slight hum when in standby but its amplified like 20 times through the speakers when the standby is switched off. Link to comment Share on other sites More sharing options...
Members dave esmond Posted March 24, 2006 Members Share Posted March 24, 2006 Hmmmm. Sounds like you need a tech. I think that covered the easy/cheap fixes. It could be all kinds of stuff. And you did try new output tubes? Both of 'em at the same time? Did you try it with both power tubes out? Doesn't sound like that's it tho. Bummer. A good tech ought to be able to get you straightened out tho'. You're in Memphis? I bet there's a few good techs around. Ask some local players who they trust. d Link to comment Share on other sites More sharing options...
Members dave esmond Posted March 24, 2006 Members Share Posted March 24, 2006 Maybe call some studios in town like Ardent and see who they use as a tech. Good techs aren't cheap. But a good one is worth every penny.http://www.memphisguide.com/directory/dir00167.htm d Link to comment Share on other sites More sharing options...
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