[cathoderay57]

Hi Gabriel, well according to Ball's data the cathode current per valve for a 6K6 in push-pull can range safely between 32-36mA (the sum of anode and screen currents). If you are currently running about 29mA I would try raising a bit more so that you are within the published range which is likely to be determined as the best compromise between output power and distortion. I'll see if I can find a couple of suitable 560R resistors and stick them in the post. If the anode current then falls within range and sounds good I'd leave it at that. For negative feedback I'm not sure exactly how to calculate the component values. I'd start using the Mullard 5-10 values and see how it sounds. Circuit attached. Be ready to turn off quickly in case you've inadvertantly cross-connected the phase of the speaker output. Cheers, Jerry