Description

very rare old stock 1959 hard vacuum 12bh7a matsu/mullard national japan preamp audio tube w/ box seam top special gold-grid edition w/ square (d) getter and w/ most precious tube-era metals = better sound reproduction national tubes feature uniform noise-free characteristics, quality and long service life, superior sound reproduction + more literature tells us these had legendary mullard quality / tone influence via 'transfer of technology' license agreement carefully curated and screened direct japan import, popular 12au7 ecc82 alternative tuning choice ~ full amplification test 105/105 % mutual gm (65-130 % good) + useful life test didnt move the meter! our unique mutual gm output test applies 225 vdc simulating actual circuits plus filtered dc simply put the higher gm scores = amplification capability via gain and bass response also supplier tested via tv7 for conductance, while your results will vary the circuit test = best test ~ give 100+ session hours w/ your specific amps voltage to fully cure (break-in is important) ships well packed worldwide, combined postage available ~ ~vintage hifidelity audio curation by cali acoustics~