Number 5 is alive

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The basic structure

Before going into too much into detail I will discuss the original structure. This amp is/was available in two versions. In the first run it seemed to have poorly-done AC heating for the tubes which resulted in hum, made worse by poor filtering of the anode voltage.
How this problem is solved is described on many pages in the net.
The second version, which I have, and will use for the following modifications already has DC heaters, a better filtering and a simple but effective tone control knob. If you are planning to buy one of those amps, make sure you buy the second version, because it will save you the time for those mods.

The output stage consists of a EL84 tube used in a single ended circuit which gets its signal from one of the 12AX7 triode systems. The preamp itself consists of the second triode system of the 12AX7 which delivers the signal through the volume potentiometer to the driver stage. Add some resistors and capacitors for tuning of the different stages and that´s it.
The result is a simple and stable structure without experiments or bells and whistles.
The whole thing is powered from a relatively well dimensioned power tranny and an extended and optimised rectification in comparison to the first run version of this amp.

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