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set of 4 direct import matsu japan 6bq5 el84, revered by audiophiles and made w/ mullard tooling expertise and engineering

these '60s production utilized transfer of technology agreements resulting in several critical audiophile advantages from mullard:

same anodes and micas, electrode geometry, glass envelope, spot welding, grid wire spacing and cathode processing chemistry
the hard vacuum japan tone is sought after by listeners for their translucent imaging and smooth warm rich sound reproduction
this matched set of 4 is twice tested and carefully curated, includes plain or branded boxes, and ships w/ free postage worldwide

full amplification test pristine quad: 100~100~101~102 % mutual gm (65 % good) + important life test pass

our life test is a key longetivity indicator, and our unique gm output test applies 225 vdc simulating actual circuit load

all tubes are also checked w/ an impeccable gas + leak/short check, and a proprietary complimentary refurb deox process

give 100+ session hours w/ your amps voltage to fully cure (breakin is important)

~ authentic vintage hifidelity audio curation by caliacoustics ~

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