Also the random (interval between two burst can be really long ... days) bursting pops are still unresolved.
---
What is interesting is that the wooden box reacts when i touch it with hand. Without instrument connected, when the master volume is approx on 2 the main buzz lowers and than I can make it buzz differently in more annoying fashion when I touch the top of the wooden box with palm. In the middle area over trebble and middle controls. It is over IC3.
Touching metal chassis do not make any change, but covering of the wooden top with palm makes 🙂.
---
What is interesting is that the wooden box reacts when i touch it with hand. Without instrument connected, when the master volume is approx on 2 the main buzz lowers and than I can make it buzz differently in more annoying fashion when I touch the top of the wooden box with palm. In the middle area over trebble and middle controls. It is over IC3.
Touching metal chassis do not make any change, but covering of the wooden top with palm makes 🙂.
Last edited:
it's got to be loss of ground somewhere in the pre-amp stage...and without being there i would think your hand is shielding rf introduced by the fault.
Hi everybody,
posting final status update to this Marshall tuning adventure.
I have replaced the non-original potentiometer with modern Alpha equivalent (little bit short threaded part I was able to fit it with some decent leg bending). Also main filter caps were replaced with axial type. Doublechecked everything else. Played some hours on it.
The intermittent burst pops were tracked down the static discharge from my office chair, the ampr or guitar somehow picks them up. Again not a real problem in standard playing situations.
The conclusion is (as it was mentioned by some commenters before) that the noise floor is irrelevant by real usage/playing. And it is more or less not worth the effort to modify the original design to make it hum/buzz less.
The amp sounds good and it is fun to play (good dynamics = reaction to right hand).
Thank you.
posting final status update to this Marshall tuning adventure.
I have replaced the non-original potentiometer with modern Alpha equivalent (little bit short threaded part I was able to fit it with some decent leg bending). Also main filter caps were replaced with axial type. Doublechecked everything else. Played some hours on it.
The intermittent burst pops were tracked down the static discharge from my office chair, the ampr or guitar somehow picks them up. Again not a real problem in standard playing situations.
The conclusion is (as it was mentioned by some commenters before) that the noise floor is irrelevant by real usage/playing. And it is more or less not worth the effort to modify the original design to make it hum/buzz less.
The amp sounds good and it is fun to play (good dynamics = reaction to right hand).
Thank you.