12AX7 / ECC83 Webcor by RCA Matched Pair Long Black Plates Square Tilt getter Made in USA '55

12AX7 / ECC83 Webcor by RCA Matched Pair Long Black Plates Square Tilt getter Made in USA '55

Description:

The 12AX7 / ECC83 Webcor , Made in USA 1955 , is a signal tube of great historical appeal, made by RCA for Webcor to the highest construction standards of American production in the mid-1950s.

The configuration with long black plates and square tilt getter identifies one of the most appreciated versions for its mechanical solidity, operational stability and authoritative sonic character. The proposed pair is selected as a Matched Pair , with coherent behavior between the two specimens and uniform sound output, fully respecting the original RCA character.

Sound Characteristics

Bass: Deep, full, and well-controlled. The low range offers body and support without overpowering the musical message, always maintaining good articulation.

Mids: This version's strong point. Rich, dense, and textured, with very present vocals and acoustic instruments delivered with the realism and harmonic depth typical of '50s RCAs.

Highs: Sweet, refined, and well-integrated. The highs are extended but never aggressive, with a naturalness that favors prolonged, non-fatiguing listening.

Dynamics: Smooth and authoritative. Excellent microdynamics and natural transient response, with a sense of continuity and control that enhances the overall musicality.

Soundstage: Wide and stable, with a well-layered soundstage and natural separation of levels. The image is credible and coherent, without artifice.

🎧 Use in Hi-Fi Amplifiers

Ideal for input and preamplification stages in medium-high and high-end hi-fi systems, where you are looking for tonal body, naturalness and musicality . Particularly suitable for jazz, vocal, classical and acoustic music.

🎸 Use in Music Applications

They are also popular in vintage and boutique guitar amplifiers, where they offer rich harmonics, expressive mids, and an authentically American character, without harshness.

🎯 Note for audiophiles

This 12AX7 / ECC83 Webcor – Long Black Plates – Square Tilt Getter – Matched Pair (1955) represents a very high quality American production , with a warm, full and deeply musical timbre.

A selected pair for those who want the classic RCA sound of the golden years , balanced and authoritative, in full coherence with the Vacuum Tubes Treasures philosophy.

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: GOOD / STRONG

Valve 1 :

• Section 1 : Gm = 1600; Ia = 1.0 mA
• Section 2 : Gm = 1600; Ia = 1.0 mA

Valve 2 :

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

• 274 535 → 274 indicates the manufacturer, i.e. RCA Victor Div., Radio Corporation of America, Camden, NJ - 535 → 5 (out of three digits) → 1955 - 35 → 35th week of the year
• 274 530 → 274 indicates the manufacturer, i.e. RCA Victor Div., Radio Corporation of America, Camden, NJ - 535 → 5 (out of three digits) → 1955 - 30 → 30th week of the year

Find out why our valves are different →