compensation cap recommendation? is conventional Ceramic NP0?

[Ian Finch]

... mainly im interested to use copper electrodes than just aluminum and Wax paper in foil as dielectric.

Good luck with that one. You'd better seal it in more wax or resin because you are in for a surprise if the copper oxidises, it later shorts or the cap drifts, is sensitive to EMI and hums and whistles to boot

 

[davidsrsb]

The Vas compensation capacitor is the last place to risk using unreliable paper oil and wax. If this capacitor fails you are looking at new output transistors and maybe speakers