Perfectly balanced vintage Mullard 12AX7 ECC83 audio tube - Made in Gt. Britain - Blackburn 1967 - Super Strong NOS - Ultra Rare. No other tubes can deliver vocals like the Blackburn Mullard's, and that's a fact. These ECC83's are extremely hard to find today and are becoming every serious audiophile's darling. And this tube, with the Telefunken logo & "Made in Germany" lettering, is even more special - the warmest sound plus the most prestigious label in the tube world!The overall tonality of Mullard ECC83 tubes is warm and lively with a very spacious sound stage. Like a warm British jacket of the finest tweed, these glorious tubes have an attractive sweet warmth in their midrange and lower regions.
The top end is silky and pleasant and doesn't get rolled off. They retain a fine sense of "air" at the top, and the upper midrange is smooth and liquid. These tubes reproduce the human voice, especially female voices, with haunting realism. The Mitcham Mullard tubes are also known to have an attractive sparkle at the top with rich bass...
Now we know where that "warm British jacket" comes from! Nearly 100% of the paint and lettering is intact on this tube, and the upside down Blackburn date code is perfectly visible: I63 B8K1 (I63 = ECC83, B = Blackburn, 7 = 1967, H = August, 3 = Week 3 of the production month). The tube tested Super Strong NOS (120%+ of nominal mutual conductance) and 100% balanced on a reliable Mercury 2000 tube tester with the following result mutual conductance both in. UMhos and in percentage of nominal. Good tubes start at 650 and new tubes incl.
NOS/NIB 1,000 - 1,050, and the Mercury 2000's rated mutual conductance (nominal) for new tubes is 1,000. Test result can also be seen in the pictures.In case you wonder what all these numbers mean to your sound experience, it's actually quite straightforward: mutual conductance directly translates to a tube's ability to amplify sound , so the higher the numbers the better. It's the least expensive option but it may take longer than other carriers.