I have recently been given a half-built tube amp that was badly assembled and had really bad buzz and hum. When I got it it was in pieces, although the basic circuit boards were still intact.
It's two channel, with an fx loop and reverb. The caps are doghouse style (side by side in a line), every single one. However, the filter caps "split" into two strings after the power section caps. One string is the preamp channel filter caps and the other is the fx and reverb filter caps.
To try and reduce the hum i thought I would do the following (can someone check my theory, please)...
1) Connect power valve cathodes (2 x 6l6 fixed bias) and the CT at the power cap negative end and create a star ground nearby
2) Connect all the filter cap negatives on both strings using a bus bar and connect the bus bars to the star ground
3) Connect the ground points from each preamp to their respective filter cap negative point on the bus bar
Here is a jpg of the schematic (I can't post a picture of the layout as there's currently nothing to show except bits)... can someone check that I'm connecting the grounds of the right parts to the right places? I've been told that sometimes where in a circuit you ground MV pots etc can make a big difference wrt hum.
It's two channel, with an fx loop and reverb. The caps are doghouse style (side by side in a line), every single one. However, the filter caps "split" into two strings after the power section caps. One string is the preamp channel filter caps and the other is the fx and reverb filter caps.
To try and reduce the hum i thought I would do the following (can someone check my theory, please)...
1) Connect power valve cathodes (2 x 6l6 fixed bias) and the CT at the power cap negative end and create a star ground nearby
2) Connect all the filter cap negatives on both strings using a bus bar and connect the bus bars to the star ground
3) Connect the ground points from each preamp to their respective filter cap negative point on the bus bar
Here is a jpg of the schematic (I can't post a picture of the layout as there's currently nothing to show except bits)... can someone check that I'm connecting the grounds of the right parts to the right places? I've been told that sometimes where in a circuit you ground MV pots etc can make a big difference wrt hum.
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