E-Linear Circuits

The E-Linear circuit is another feedback method that can be used with  SE amplifiers that feature tetrode or pentode finals and UL output transformers.

Typically ,  there is a high gm pentode driver stage.  The B+ supply for the driver tube is taken from the UL tap on the output transformer.   This sort of feedback is said to be similar to plate to grid feedback that is used on the popular RH amplifiers.

One feature of the E-Linear feedback circuit that might be an advantage is that  the B+ for driver and output stages of a 2-stage SE tube amp can be taken from a single node of the power supply filter.  This might be a good attribute for "LOW DCR" SE tube amp builders utilize in order to get rid of the extra RC section in our PS filters.

Below is an example of the E-Linear feedback connection as used in a SE DC tube amplifier.   

Note : this schematic has only be developed in LTSpiceIV but I have not built or listened it. 

As always, proceed with caution.

DT 667   1/6/2020