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Amperex 6DJ8 ECC88 Matched Pair Yellow Tip - HP Select - Holland 1961 GA0 - NOS

Amperex 6DJ8 ECC88 Matched Pair Yellow Tip - HP Select - Holland 1961 GA0 - NOS

Regular price $154.00 USD
Regular price Sale price $154.00 USD
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Sound Sample:

Perfectly matched & balanced pair of vintage HP Select Amperex 6DJ8 ECC88 audio tubes - Heerlen sound from 1961 - Super Strong NOS - Very Rare

Tube Summary

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. 

Sound Qualities

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.) To see how these sound differently from their German counterparts, please feel free to take at a look a wonderful pair of Siemens 6DJ8's we recently sold here:

Professional Sound Evaluation

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.

Professional Tube Testing

NO short, leakage or gas. NO noise or microphonics.

Both tubes tested Strong NOS (110%+ nominal mutual conductance) on a reliable and regularly calibrated Mercury 2000 tube tester with the following result (mutual conductance in both uMhos and percentage of nominal value):

Tube 1: 14,500/14,000 (116%/112%)
Tube 2: 14,200/14,000 (113%/112%)

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. 

Appearance & cosmetic condition

Besides its remarkable sound characteristics, we also treasure this pair for its near pristine cosmetic condition given the tubes' age - at least 90% of the paint is still intact on both tubes, and the very close (practically identical) acid-etched date codes of the Heerlen factory are perfectly visible on both tubes: 

delta 1F2 (delta = Heerlen, 1 = 1961, F = June, 2 = Week 2 of the production month)
delta 1E5 (delta = Heerlen, 1 = 1961, E = May, 5 = Week 5 of the production month)
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