noise when I chopstick!

dast · Post by **dast** » Mon Jan 21, 2008 6:06 pm

hi,
I have a loud noise when I chopstick the green wire from the 470k mix resistors + cap to the 2nd tube pin 2.

The joints look good but I plan to resolder. Is there any other explanation or something I should look for besides cold solder joint?

thanks,
Dave

rockstah · Post by **rockstah** » Mon Jan 21, 2008 6:11 pm

how loud is the noise? do u mean you hear the chop stick tapping? that is a grid wire( input to the tube) after all.
it seems it would pickup noise of you tapping if you tapped on it with the amp on.

dast · Post by **dast** » Mon Jan 21, 2008 6:11 pm

I meant the 2nd preamp tube

rockstah · Post by **rockstah** » Mon Jan 21, 2008 6:12 pm

pin 2 and pin 7 are grids / inputs - again what kind of noise is it?

dast · Post by **dast** » Mon Jan 21, 2008 6:18 pm

it's a fairly loud hum. It is much louder on tube 2 than when I tap the grid pins on the 1st tube. And it's only pin 2 - not 7 of the 2nd tube
thanks,
Dave

dast · Post by **dast** » Mon Jan 21, 2008 6:24 pm

preamp tube #1 seems microphonic to tap - what I would expect, more or less. But tube 2 seems different, there is much more of a loud buzzing when I tap any of the resistors, cap, or wire or pin 2.

Perhaps I'm grasping at straws - I'm trying to reduce what I feel is abnormal noise in the amp. When I pull preamp tube 1 there is no change. When I pull tube 2, noise goes away.

thanks,
Dave

planetjimi · Post by **planetjimi** » Mon Jan 21, 2008 7:28 pm

Tap on it with a hammer the noise will go away!!

Sorry I had to say it, I was chopsticking my way throught the amp all weekend. I get noise on pin 2 also.

Metropoulos Forum

noise when I chopstick!

noise when I chopstick!

2nd preamp tube, I mean. no content in message

loud hum

preamp 1 seems microphonic to tap