Originally posted by Tom Phillips
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Here's the thing... At this point I'm inclined to think that the problem going away on a different outlet may not be directly related. But rather, that particular area of the house doen't have as much noise that the pickups can hear. The absolute fact is that if you can turn your guitar down to zero and the buzz stops then the buzz is coming from the guitar. Not the AC line, it's not a poor ground, not the amp. Have you tried a new instrument cable?"Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by Jazz P Bass View PostThe fact that ' amp turned down & no noise ' does not eliminate triac light dimmers injecting crap directly into the line.
BTW, I just tested my house wiring with my meter and got zero ohms between the AC wall plug center pin and the cold water piping. Not that your post above said it COULDN'T be that way. But I think it implied that it doesn't need to be that way."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Guys, i think maybe i need to elaborate a bit before you go barking up the wrong tree. If i insert the guitar at the second stage it's dead quiet. Granted, theres one less gain stage to amplify any noise, but from this to dead quiet seems to indicate theres something going on at the input. And also if i touch places with AC signal i get a loud hum just like you'd expect touching say the tip of the jack. But after the 1st stage i can touch any part of the signal path and it makes zero noise. The input is very sensitive. Even as my finger is just right up on a part but not quite touching it you hear hum starting. If i grab the body, not the leads but just the body of the 1M ground resistor at the input it gets loud.
heres another things thats odd and maybe will be a hint. I used to use those russian mullard reissue 12ax7's and they worked fine. At some point after some tweaking i'm sure, they no longer worked right. It sounded like a bad ground resistor at the grid when i'd try them. The note would die and static...you know the scenario. All other tubes i've tried work fine but those. I'm thinking the issue is related.
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Originally posted by daz View PostThe input is very sensitive. Even as my finger is just right up on a part but not quite touching it you hear hum starting. If i grab the body, not the leads but just the body of the 1M ground resistor at the input it gets loud.
Originally posted by daz View Postheres another things thats odd and maybe will be a hint. I used to use those russian mullard reissue 12ax7's and they worked fine. At some point after some tweaking i'm sure, they no longer worked right. It sounded like a bad ground resistor at the grid when i'd try them. The note would die and static...you know the scenario. All other tubes i've tried work fine but those. I'm thinking the issue is related.
I know you've checked your input circuit carefully and even tried isolating the jacks. Maybe try your rig side by side with another amp set to similar gain in place of yours. Then at least you can rest knowing the problem is not your gear. I'm still thinking EMF. That's all that's left when you burn it down."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz
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Originally posted by Chuck H View PostThat's normal IMHE
I hate to say it... I've had a lot of trouble with the rusky tubes. Noisy out of the box or funny intermodulations. NOS tubes are a crapshoot half the time anymore. I'm actually considering Chinese preamp tubes!?! I've used up my stock of RCA's and there's only one Russian tube that sounds "right" IMHO. The Sovtek 12ax7LPS. And those sound great but they're all way too microphonic for the first preamp slot. So I may try the Shuguang 12ax7 for V1.
I know you've checked your input circuit carefully and even tried isolating the jacks. Maybe try your rig side by side with another amp set to similar gain in place of yours. Then at least you can rest knowing the problem is not your gear. I'm still thinking EMF. That's all that's left when you burn it down.
My only other amp is another build that i sorta cannibalized the preamp on so it's just a PA that i use with a insert point at the PI for a effects return amp. But in any case it's far less noise at that certain mains socket to i gotta think theres something in that room. I patched a few cords together last nite so i could leave the amp there and walk into the room with the "good" outlet and i couldn't get that far. But i got close enough that i don't think theres EMF causing it or it should have gotten quiet when i went in there
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