revered by audiophiles worldwide, these vintage hard vacuum matsu japan 6fq7 (6cg7) are top sonic echelon mullard alternatives
the rarest pure tone gold-grid editions w/ special communication codes are premium grade selected and screened, matched quad
take your listening experience to a higher level of dimensional engaging detail, immersive harmonic imaging and transparency
transform sound reproduction and realistic playback across multiple genres w/ rich bass depth and holographic textured resolve
translucent highs and warm mid-band tone euphony, live-concert style delineation between instruments vocals and percussion

the british supplied expert engineering via 'transfer of technology' tooling provides several critical audiophile advantages:
same anodes, micas, electrode geometry, glass envelope, spot welding, grid wire spacing and cathode processing chemistry
these 4 old stock audio tubes are carefully curated via direct japan import + twice tested for mutual gm + boxes included

full conductance test 104/102~104/104~106/104~104/105 % mutual gm (65% good) + life test pass (a key longetivity indicator)
our special gm output test applies real world 225vdc voltages w/ filtered dc + an impeccable gas test + leak/short check
we also pride ourselves on a proprietary complimentary value-added complete refurb screening deox process
give 100+ session hours w/ your specific amps voltage to fully settle in (break-in is important)
ships well packed worldwide w/ free economy postage

(a fan favorite top seller in 12ax7, 12at7, 12au7, we also have these in 5ar4, 6ca7, 6bq5, and more varieties available)

authentic vintage hifidelity audiophile / preamp / mic tube curation by caliacoustics, see our new website!
+ limited special editions + true-nos rare sealed box + pinched waist + high-resolution headphones