rectifier tube, Resistors on which side ?

[Colas LeGrippa]

Hi,

is it best to put resistors on the AC or DC side of a rectifier ?

Colas

[tubeswell]

either way will work, but neither is absolutely necessary

Merlin recommends them on the plate side (as a belts and braces approach) to enhance the longevity of a tube rectifier (at the expense of a bit of B+ voltage) http://www.freewebs.com/valvewizard/fullwave.html

Others use them in the B+ rail to create sag

[Colas LeGrippa]

Do the diodes toward the recto tube remove the ''tone'' of the tube, the voltage being already rectified ?

Colas

[HotBluePlates]

Do the diodes toward the recto tube remove the ''tone'' of the tube, the voltage being already rectified ?

No.

If the solid-state diodes are nearly zero resistance when that particular tube rectifier plate is conducting, then the apparent resistance of the tube (which causes the voltage sag you want) dominates the situation.

The solid-state diodes only come into play if the tube rectifier is short-circuited. If the sand diodes weren't there, filter caps will pop due to high negative voltage being applied to them (which the tube rectifier would have blocked). The solid-state diodes keep the amp working. *If* you can hear a difference between the tube and solid-state diodes, then you know to go back and check the health of your rectifier.

[tubeswell]

The forward voltage drop of a 1N4007 is about 0.6V, which makes diddly squat difference to the power output when combined with a tube rectifier. I use SS diodes for protection against tube rectifier shorting on all my tube-rectified amps. Makes no difference in sound or power output and is only a few cents worth of extra insurance.

[HotBluePlates]

What Tubeswell said. 

[Colas LeGrippa]

thanks for the explanations !