Feedback
I'm building a lower volume variant of a classic guitar amplifier, and I'm keen to retain as much as possible the original circuits distortion characteristics. The stock amplifier circuit uses 2 x 6L6 in fixed bias push pull. My practice amp will instead use a pair of EL91's.
The original amplifier design uses the 4ohm OT tap to provide global negative feedback to the phase splitter, but for the EL91 valves, I only have at hand a transformer with one 15ohm tap.
The 15ohm tap would provide approximately twice the feedback voltage of a 4ohm tap.
Am I correct in thinking that because the drive voltage requirements for the EL91 valves is lower than that for the 6L6 valves that using the 15ohm output will somewhat correct for the lower drive voltage of the valves I'm using?
... or am I just going to end up with potentially too much drive for the EL91's but with less phase splitter clipping than if I instead obtained an output transformer with a 4ohm tap and split the anode load resistors of the phase splitter to tap off the required drive voltage for the EL91 valves?
|