6J7G-GT / 6SJ7GT / 6K6

The valves of the 6SJ.. or 6J.. or 6SK.. series are excellent pentodes designed and produced between the early '40s and the end of the '70s, mainly for military use but easily used also in the civil sector. Due to their characteristics, they are perfectly suited for use in Low Frequency as pre-amplifiers or signal amplifiers, in fact already used, in the 50s-60s, in numerous particularly adventurous and alternative amplification circuits but with amazing results.