The overall tonality of Mullard ECC88 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! Both tubes tested Strong NOS (110%+ nominal mutual conductance) on a Mercury 2000 tube tester with the following result mutual conductance measurements both in. UMhos and in percentage of nominal. Tube 1: 14,000/13,600 (112%/109%). Tube 2: 14,000/13,800 (112%/110%). Good tubes start at 7000 and new tubes incl. NOS/NIB 12,500 - 13,000, and the Mercury 2000's rated mutual conductance (nominal) for new tubes is 12,500.
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 stronger.Although one of the tubes (the IEC labeled one) has nearly half of the paint and lettering due to storage, the other tube is in excellent cosmetic condition, and the Blackburn date codes are perfectly visible on both tubes. B3C1 (B = Blackburn, 3 = 1963, C = March, 1 = 1th week of the month). B4L2 (B = Blackburn, 4 = 1964, L = December, 2 = 2rd week of the month). Customers outside the US please pay extra attention. Soundlumia sets extremely high quality standard for the products we deliver. Sound experience is a very subjective thing, and let's be real it's not that easy to run into compatibility issues between amps and tubes so that one won't fly, either. Secondly, if you are a tube roller looking to game the return system, Number One STOP. We have seen it all and we know what you're up to.