2 NOS Matched'63 Mullard Blackburn ECC81 12AT7 Preamp AudioTubes + Free Postage

Audiophile crown jewels, revered worldwide for their rich holographic sound stage imaging. Set of 2 vintage mullard blackburn 12at7 ecc81 audio / preamp vacuum tubes. Pristine matched pair w/ authentic b3a2 / b3j4 etch codes and mullard boxes, old production 1963. Carefully curated screened and twice tested, plus complimentary proprietary refurb deox process.

Full gm conductance test 104/110 106/107 % gm (65) + important life test pass! (life check = longetivity indicator). Our special gm output test applies real world 225vdc voltages w/ filtered dc, plus an impeccable gas test and leak/short check.

Mutual gm conductance scores are the ability to transfer current especially important for push-pull preamps. Also double checked (twice tested) for mutual gm conductance via supplier tv7 / hickok 539c.

Give 100+ session hours w/ your specific amps voltage to fully settle in (break-in is important). Authentic vintage hifidelity audiophile / preamp / mic tube curation by caliacoustics. Including limited special editions + rare true-nos sealed box + pinched waist. Also high-resolution headphones + premium vocal stage and studio mics. 6dj8 7dj8 6922 7308 / ecc88 pcc88 e88cc e188cc cca.

12ax7 12at7 12au7 12bh7 / ecc83 ecc82 ecc81 e82cc. 6bq5 6au6 6267 6ca7 6ca4 6aq5 / 6v6 6l6 6sl7 6sn7 5y3 5u4 5ar4. 5814 5751 5965 6189 6201 7062 7189 / cv2492 cv4004 cv455 cv4085. El34 el84 ef86 ef94 ez81 ecc85 e180cc gz34.