Russian 6N1P-VI tube high-quality double triode. Low noise and microphonic effect. Optimised for "pulsed" mode of operation. Equivalent to the 6DJ8, ECC88, 6922
Russian 6N3P-E double triode tube with separate indirectly heated cathodes, low frequency preamplifier. Extended product life. Near analogue: ECC42, 2C51, 5670, 6385