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Philips ECC83 12AX7 Matched Pair - 14mm Short Plates I65 - Heerlen, NL '62 - NOS

Philips ECC83 12AX7 Matched Pair - 14mm Short Plates I65 - Heerlen, NL '62 - NOS

Regular price $212.00 USD
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Tube Summary
The "textbook Heerlen sound" has been referenced in several Soundlumia ECC83/12AX7 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 Characteristics 

The most distinctive sound feature of the Heerlen ECC83'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 the high end German ECC83's (Siemens, Telefunken, Valvo etc.) We would recommend these as an excellent choice if you are seeking the high end ECC83 tubes that can deliver the legendary Philips house sound flawlessly. 

Professional Tube Testing

This set was tested and certified by RoeTest V11 tester with the following result: 

Tube 1: 

Measured transconductance (GM): 1.58/1.43 mA/V  - 99%/89%  (100% = 1.6 mA/V)
Measured plate current (IA): 1.172/0.94 mA  - 98%/78%  (100% = 1.2 mA)

Tube 2:

Measured transconductance (GM): 1.55/1.6 mA/V  - 97%/100%  (100% = 1.6 mA/V)
Measured plate current (IA): 1.067/1.142 mA  - 89%/95%  (100% = 1.2 mA)

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

Curve trace is also included in the original RoeTest report.

Appearance & Cosmetic condition

This pair stands out aesthetically among the vintage tubes. At least 90% of the silkscreen is well preserved and the acid-etched Heerlen date codes are perfectly visible on both tubes:

I65 ⊿2D1 (I65 = ECC83 short plates production gen #5, 
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