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

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

Description:

The 12AX7 TELEFUNKEN , in the prestigious Ribbed Plates version with the 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.

Sound Characteristics

Bass: The low range is dry, precise, and very controlled . There is no artificial emphasis: the bass is uncluttered, fast, and legible, contributing to a solid, stable foundation, particularly suited to systems that prioritize clarity and articulation.

Mids: The strong point of this design. The mids are extremely linear, transparent, and neutral , with vocals faithfully reproduced to their original timbre. Acoustic instruments emerge with great clarity and lack of coloration, making this tube ideal for high-resolution systems.

Highs: Clean, extended, and finely refined. The high end is airy yet controlled , with a very fine grain and no harshness. Listening is open and stable, without fatigue even over long periods.

Dynamics: Measured and coherent. The response prioritizes microdynamics and the continuity of the musical message, avoiding any dramatic effects. Transients are rendered with precision and naturalness.

Soundstage: The soundstage is tidy, stable, and well-focused . The separation of planes is clear, with believable depth and a rational imaging, typical of the Telefunken approach.

🎧 Use in Hi-Fi Amplifiers

Ideal for preamplifiers and input stages of hi-fi systems that require neutrality, transparency, and tonal accuracy . Particularly suitable for already balanced systems, where you want to preserve signal fidelity without introducing coloration.

🎸 Use in Music Applications

They are also popular in instrument amplifiers and studio equipment, especially where definition, quietness, and predictable response are required. They offer a clean, controlled sound with great detail readability.

🎯 Note for audiophiles

This pair of 12AX7 / ECC83 TELEFUNKEN Ribbed Plates – Diamond Bottom is intended for the experienced audiophile who appreciates a technical, balanced and rigorous approach.
Selection and testing ensure stability and operational consistency, without resorting to promises of absolute numerical symmetry. An honest, defensible, and musically correct proposal, in line with the Vacuum Tubes Treasures philosophy: the valve as an instrument of fidelity, not as an artifice.

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 / VERY STRONG

Valve 1 :

• Section 1 : Gm = 1700; Ia = 1.3 mA
• Section 2 : Gm = 1500; Ia = 0.9 mA

Valve 2 :

• Section 1 : Gm = 1600; Ia = 1.0 mA
• Section 2 : Gm = 1700; Ia = 1.2 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.
  
• Cosmetic condition: Good – Lettering partially eroded, but still legible. Valve body in good condition. See photos for details.
  
• Manufacturing Code: Unreadable – Telefunken production, identifiable by construction features. 1960s

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