Constant "electric" hum on crack

[bottleheaduser3000]

Hi all
finished my crack 2 months ago (with speedball) and I've been loving it since.
Today I started noticing a little "hum" in the right ear pad (HD650)
He hum goes away if I lift the front of the plate 1cm (0.3 inch)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FtwGsH3f.png&hash=9b3256476222001443897435df084726e2943f3c)

It also goes away when I lift the back up

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FfN2v4SV.png&hash=2be528ff5db0b239fe499b767ddbe33b7f9b25b6)

What could this be ?

[Paul Birkeland]

This is very likely a loose connection in the amplifier that is responding to being moved physically.

We generally recommend reheating all of your solder joints in instances like these.

-PB

[bottleheaduser3000]

Could it be the big tube ?
When I tilt that one a bit it also stops.

[Paul Birkeland]

Could it be the big tube ?
When I tilt that one a bit it also stops.

Yes, that would suggest a loose connection on the octal socket, or a wire leaving the octal socket and going elsewhere.

-PB

[bottleheaduser3000]

checked everything. could it be the big tube? when wiggling it the humming goes away.

[Doc B.]

Based upon your description, it's more likely to be the tube pins losing contact with the socket or a loose wire on the socket than the tube itself. Try cleaning the pins of the tube with a scotchbrite pad or some really fine sandpaper.