NOTE THERE IS A TYPO IN THE TITLE WHICH SHOULD READ ECC82 AND NOT ECC83. Unfortunately the title cannot be edited.
I have a very large box of 12AU7's I tube rolled over the last decade and in my opinion this is the very best sounding 12AU7 ever made. I used one in my Hovland HP100 and also in a Minimax pre-amp. In both pre-amps, across the musical scale top to bottom, this tube just sounded more musical and natural than all others. I also tried the gold version of the 10M ECC82 Mullard and found it to be to softer with a slight loss of detail. I have two of these left, one is NOS in the box, the other is used but tests quite good. These tubes were rated for 10,000 hours of service and the used tube has quite a few years of use left.
Both tube are marked "Master 10M Series", "Made In Great Britian" and have the following individual markings:
NOS 10M: GF2/B5L1 and 1022-701. tested @: 2350/2350 (a New tube is listed as 2200/2200)
Used 10M: GF2/B5L2 and 1022-625 tested @ 1910/1900
There is only one tube box and both tubes will be shipped in this box and wrapped for protection. Shipping will be via a priority mail box. Shipping only to the USA and included in the price.