Perfectly matched & balanced pair of vintage HP Select Amperex 6DJ8(ECC88) audio tubes - Heerlen sound from 1959 - Super Strong NOS - Very Rare. These are the legendary "medical tubes" made by Amperex Holland for Hewlett-Packard's medical devices distributed around the world. Each tube had to go through rigorous test and selection processes designed, implemented and monitored by HP. What you get is the best from the best candidates in build quality and low noise. Despite the HP label, you get the "textbook" Amperex Holland midrange presentation that is transparent, natural and expansive, with a slight touch of warmth that illuminates your musical world.
The top end is super airy, smooth and nicely extended like one would expect from the best Siemens tubes. Vocals are intimate, sweet and forward (but not right in your face) and that always reminds me how the vocals sound on the best Mullard tubes. Bass is deep and well controlled and the accuracy feels very similar to the high end German ECC88's Siemens, Telefunken. This pair of Amperex 6DJ8's have same date code etched on glass: delta 9L delta = Heerlen, Holland, 9 = 1959, L = December. They also stand out aesthetically among the vintage tubes.Over 85% of the silkscreen is well preserved. Professional testing & sound evaluation.
Both tubes tested Super Strong NOS (120%+ nominal mutual conductance) on a Mercury 2000 tube tester with the following result mutual conductance in. Tube 1: 13,800/13,100. Tube 2: 15,300/14,000.
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 better. The pair worked wonderfully & sounded terrific in our test amp Liquid Platinum by Alex Cavalli. All the tubes I list for sale are guaranteed to work because we run professional tests and listening sessions on them before packing. I would really appreciate it. Secondly, if you are a tube roller looking to game the return system, Number One STOP.
So no tricks here please. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Parts & Accessories\Vintage Tubes & Tube Sockets". The seller is "frankshaohuawang" and is located in this country: US. This item can be shipped worldwide.