Mullard 12AX7 ECC83 Matched Pair Blackburn 1959 Heath + Philips Labels NOS

Mullard 12AX7 ECC83 Matched Pair - Blackburn 1959 - Heath + Philips Labels - NOS. 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 pair, with the rare Heath and Philips labels, is even more special - the warmest sound plus two of the best known tube brands in the 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 British made 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! Both tubes have nearly 100% of the paint and lettering remaining, and the close Blackburn date codes are perfectly visible.

B9I (B = Blackburn, 9 = 1959, I = September). NO shorts, leakage or gas. One tubes tested NOS (100%+ of nominal mutual conductance) on a reliable Mercury 2000 tube tester with the following result mutual conductance both in. UMhos and in percentage of nominal. Tube 1: 1,000/1,000(100%/100%).

Tube 2: 1,080/1,050(105%/103%). 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.