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Amperex Holland 6922 E88CC D-getter Matched Pair - 7L4 ⊿9D - Heerlen 1959 - NOS

Amperex Holland 6922 E88CC D-getter Matched Pair - 7L4 ⊿9D - Heerlen 1959 - NOS

Regular price $645.00 USD
Regular price Sale price $645.00 USD
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Sound Sample:

Product Summary

The "textbook Heerlen sound" has been referenced in several Soundlumia E88CC listings, and many tube enthusiasts asked what all that means. So here is the answer: the late 1950s and very early 1960s tone, the beginning of over a decade's excellence in sound, the classic tonal template for all the great (and greater) Amperex/Philips/Valvo/Miniwatt tubes to be made in the years to come, the timeless Philips radio tone that many of us grew up listening to. 

Sound Qualities

The most distinctive sound feature of Holland PQ 6922's is the transparent, natural and expansive midrange presentation, with a slight touch of warmth that illuminates your music. Every piece of music you play through these tubes sounds like from a vinyl record, whether your sound source is phono or not. The sound stage is spacious, deep and structured. Bass is incredibly deep but well controlled and feels as accurate as on super high-end German E88CC and CCa tubes. Thanks to the super rare d-getter on this pair, you get with fast response (as in the solid-state fast), overwhelming detail in sound and the realistic bass - this is truly the Holy Grail sound from the Heerlen factory.

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 

Both tubes tested Strong NOS (110%+ nominal mutual conductance) on a Mercury 2000 tube tester with the following result (mutual conductance in uMhos):

Tube 1: 16,200/16,200 (130%/130%)
Tube 2: 15,750/15,800 (126%/126%)

Good tubes start around 7000 and new tubes (incl. NOS/NIB) 12,500 - 13,000, and 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 tube's ability to amplify sound so the higher the numbers the stronger. 

Appearance & cosmetic condition

Beside the world-class sound characteristics, we treasure this pair because the pristine condition the two tubes are in - nearly 100% of the paint is intact, and the identical Amperex New York date codes etched on glass are perfectly visible:

7L4 ⊿9D (7L4 = 6922/E88CC production #4,  = Amperex Holland, 9 = 1959, D = April) 
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