12AX7 ECC83 TELEFUNKEN Tested Pair Tubes – Smooth Plates Diamond Bottom Made in Germany

12AX7 ( ECC83 ) TELEFUNKEN Smooth Plates Diamond <> Bottom Tested Pair Tubes Made in Germany '60s

Description:

The 12AX7 TELEFUNKEN , in the prestigious Smooth Plates version with diamond logo <> engraved on the bottom , represents one of the most refined and sought-after expressions in the history of European valve production.
This tested pair, produced in Germany in the 60s , is distinguished by an extremely clean, neutral and stable sound, which makes it an absolute reference for top-level hi-fi applications, recording studios and professional audio equipment.

Bass : Fast, clean, and articulate. Low frequencies are present with surgical precision, without exuberance or slowness. Ideal for systems requiring timbre rigor and immediate response in the low range.

Mids : Extraordinarily transparent and neutral. Voices are centered, detailed, and natural, with a sober and faithful timbre. Acoustic instruments are rendered clearly, without any artificial coloration or emphasis. The midrange is this tube's undisputed strength.

Highs : extended, bright, and always under control. The upper end is airy, but never sharp or aggressive. The clarity is refined, contributing to the airiness of the soundstage without compromising listening comfort.

Dynamics : Impeccable. Transient response is fast yet fluid, with an expressive naturalness that enhances every dynamic nuance. Even the most sudden excursions are handled with balance and coherence.

Soundstage : wide, deep, and perfectly defined. The stereo image is clear, stable, and well-focused, with very accurate separation of sound planes. The scene opens up realistically and controlled, without artifice.

The 12AX7 TELEFUNKEN Smooth Plates – Diamond Bottom – Made in Germany '60s , is a valve with an analytical, balanced and highly musical character, ideal for those who want maximum neutrality without sacrificing detail and micro-dynamics .

🎧 Use in Headphone Amplifiers and Hi-Fi Driver Stages

Perfect for high-end preamplifiers, tube DACs, and reference headphone amplifiers. It offers transparent, quiet, and detailed performance, ideal with headphones like the Sennheiser HD800S , Focal Utopia , Beyerdynamic T1 , or ZMF Vérité . The spatial reconstruction and harmonic response are benchmark.

🎸 Use in Guitar and Bass Amplifiers

Highly prized in music for its tonal consistency and lack of harshness. Used in vintage Fender, Vox AC30, and Marshall Plexi amps, it delivers a defined, fluid, and harmonically rich sound, both clean and in controlled overdrive.

🎯 Note for audiophiles and technicians
One of the most neutral and musical valves ever made, recommended for those who want absolute transparency, dynamic balance and tonal refinement , without introducing character.

Test Results

Tested on AMPLITREX AT-1000 Tube Tester

Voltage Test: Va = 250V, Vg = -2V
Average 100%: Gm = 1600 ; Ia = 1.2 mA
TEST RESULT: STRONG / GOOD

Valve 1 :

• Section 1 : Gm = 1500; Ia = 0.9 mA
• Section 2 : Gm = 1400; Ia = 0.8mA

Valve 2 :

• Section 1 : Gm = 1400; Ia = 0.7 mA
• Section 2 : Gm = 1300; Ia = 0.6 mA

• Microphonics: Low Noise & Microphonics – Tested and compliant for use in hi-fi systems and guitar amplifiers.
• Output Quality: Excellent – Very strong and stable output, no fluctuations.
• Short circuits and GAS: Absent.

Conditions:

• Condition: Vintage tubes - Tested and in perfect working order. Shipped in our custom box for optimal protection.
  
• Functionality: Fully functional.
  
• Aesthetic condition: Very good – Clearly legible writing with minor signs of wear, no obvious defects. See photos for details.
  
• Manufacturing Code: Unreadable – Telefunken production, identifiable by construction features. 1960s

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