EL34 push pull DIY project


Ultra Linear PP EL34 amp

This is Giannis Spathopoulos EL34 amp push pull diy project. It is a classic push pull amp design .
It is an ultra linear mode PP amp uses the EF86 (voltage gain) and the 6FQ7 (phase splitter )tubes at the driving stage. The output transformers are hand made (P&K audio). We build this amp in a ready-made chassis.It is all hard wired using silver Teflon cables in all critical paths. Listening this amp our first impression was very good. It has really excellent performance.

After some testings we publish the first draft schematic. Note that we apply no feedback at all. The plate-to-plate loading of the output stage is 5k Ohms and, the line voltage is 430 Volts. The Bias applied voltage is -47Volts ( -35V grid).
Input sensitivity measured at 1kHz is about 7.5 mV for an output of approximately 25 W with no feedback. Total harmonic distortion is about 1% when no feedback is applied.

Measurements and , data will be available soon.
We continue testing it and listening to it performing the necessary fine tuning.

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Giannis Spathopoulos