And the award of "the quietest tube on the planet" goes to...Amperex Holland 7025! Virtually identical to ECC83/12AX7 but with nearly non-existent hum and noise thanks to the unique spiral wound filament design that effectively packs two tubes in one glass envelop, the Holland made 7025 tubes preferred by audio professionals and hardcore enthusiasts.
Sound Qualities
We have evaluated at least 10 different versions of Orange Globe tubes and the mid-1960s' Holland sound is clearly among the best. 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 ECC83's (Siemens, Telefunken.)
Professional Tube Testing
NO shorts, leakage or gas. NO noise or microphonics.
This set was tested and certified by RoeTest V11 tester with the following result (percentage of nominal plate current [mA] ):
Tube 1: 108%/109%
100% = NEW/NOS
Curve trace is also included in the test report.
Appearance & cosmetic condition
we treasure this pair because the pristine cosmetic condition the two tubes are in - over 90% of the paint is intact. The identical Heerlen date codes etched on glass are perfectly visible on both tubes. What a rare find!
⊿1I1 ( ⊿ = Heerlen, 1 = 1971, I = September, 1 = 1st week of the month)
