Hi to all, i just built a low watt amplifier using 2x miniwatt tube NOS Philips EL91 in push pull for a total output power of 4 watt. I used a Hammond 125B OT for 8 ohm secondary and 22.5K primary impedance. the ampli sounds great, as i aspected, but i canno get 4 watt out of my secondary OT, but only 2.3. I configured tubes as datasheet suggests for class AB push-pull amplifier, i.e. 250V on the plates, 560 ohm as shared cathode resistor for a grid-to-cathode bias voltage of -13.5. Power stage is driven by cathodyne PI with a 6C4 tube which is not overdriving for the moment. Now for power test, i followd this procedure: Inject 1 KHz signal into ampli and turn up volume before the clipping point, where the wave form is a clear sine. Then measure voltage at the leads of 8 ohm dummy load and apply formula P = (V*V) / R. I am puzzling myself to know why but i am not understanding, could you please give me any suggestion o what may i check ?