Blackburn or Heerlen, and that's a fact. These E88CC tubes are particularly special because they have the very rare yellow print and Cossor label and are being hunted to near extinction by audiophiles and sound professionals. And yes the "British Made" lettering is a BIG deal not only because it certifies the tube's true Gt. Britain origin but also because it appeared on select batches of Mullard tubes from select years of manufacturing only. 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 human voice, especially female voices, with haunting realism. Full disclosure from your peer audiophile: Mitcham E88CC's are my go-to tubes for listening to Maria Callas and Frank Sinatra and I refuse to use other tubes.
Mitcham Mullard's are also known to have an attractive sparkle at the top with rich bass... Now we know where that "warm British jacket" comes from! The pair worked wonderfully and sounded terrific in our professional studio setup for monitoring.
Input: Cambridge Audio CXC V2 dedicated CD transport + Schiit Audio Bifrost 2 Multibit DAC. Amplification: Liquid Platinum Tube Amplifier by Alex Cavalli. Output: Focal Clear MG Pro open-back headphones. Our full tube sound review was written 100% based on the actual listening experience while this pair of tubes were running in the system described above.
Both tubes tested Strong NOS (110%+ nominal mutual conductance) on a Mercury 2000 tube tester with the following result (mutual conductance in uMhos and percentage of nominal). Tube 1 (Left): 13,000/1. Tube 2 (Right): 14,000/14,200 (112%/114%).
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 would 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. We treasure this pair also because of the pristine condition of both tubes - over 90% of the paint and lettering are well retained. The Mitcham date codes painted glass are also visible on both tubes. 7L1 = change code, R = Mitcham, 0 = 1960, H = Sep, ? = unknown week of the month. 7L1 R1B4 (7L1 = change code, R = Mitcham, 1 = 1961, B = February , 4 = 4th week of the month). We set 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.