Greg70
New Head-Fier
- Joined
- May 24, 2014
- Posts
- 25
- Likes
- 25
fccn75
It sounds like you have a very microphonic tube in there, most likely one of the 12AU7s, and yes I've had it with a bad tube.
Remember the sockets, boards and chassis are all solidly attached to one another so tapping the chassis will transfer to that tube even without the socket directly touching the chassis.
You can generally locate the bad tube by lightly tapping it with a fingernail with no music playing.
Even a good pre-amp tube will give a slight ping when you do this, but you'll know the difference with a bad one.
It sounds like you have a very microphonic tube in there, most likely one of the 12AU7s, and yes I've had it with a bad tube.
Remember the sockets, boards and chassis are all solidly attached to one another so tapping the chassis will transfer to that tube even without the socket directly touching the chassis.
You can generally locate the bad tube by lightly tapping it with a fingernail with no music playing.
Even a good pre-amp tube will give a slight ping when you do this, but you'll know the difference with a bad one.