CV4024 VALVO Hamburg, Germany, interchangeable with 6201, E81CC, ECC801S, 12AT7WA, M8162.
Extremely rare "super ECC81" with GOLD Pins and 17mm tall anodes, made in Germany tube code Df6 = 6201, factory code (see picture, might vary with available stock) D3E4 = VALVO Hamburg, 1963, May, 4th week.
