12AX7 / ECC83 GE Short Gray Plates Halo Getter Tested Tube Made in USA

12AX7 / ECC83 GE – Short Gray Plates – Halo Getter – Made in USA

AMPLITREX Tested – STRONG – Low Noise & Microphonics – Vintage American General Electric Production

Test Results:

Tube tested on AMPLITREX AT-1000 Tube Tester:

• Test Conditions: Va = 250V ; Vg = -2V
• 100% Average: Gm = 1600 ; Ia = 1.2 mA
• Test Result: STRONG

Tube :

• Section 1: Gm = 1400 ; Ia = 0.8 mA
• Section 2: Gm = 1430 ; Ia = 0.8 mA

• Burn-in / Stability Test: 48h – OK
• Microphonics: Low. Tested and suitable for use in hi-fi and guitar amplifiers, even in V1.
• Balance: Excellent - The sections are consistent and well-aligned, making the tube suitable even for use as a phase inverter in hi-fi and instrument applications.
• Emission Quality: Strong – Strong and even emission, suitable for any application.
• Short Circuits and GAS: None.

Description

Selected vintage specimen of 12AX7 / ECC83 General Electric, produced in the United States and dating approximately to the 1970s based on its construction features. The tube features the classic Short Gray Plates with Halo Getter configuration, representative of American GE production from this period. An authentic vintage tube, particularly interesting for audiophiles and musicians seeking original components, carefully verified and with documented electrical characteristics.

The measurements performed with Amplitrex AT-1000 show a transconductance of 1400 and 1430 µmhos in the respective sections, with an average of 1415 µmhos, compared to the nominal reference of 1600. The anode currents are perfectly uniform, equal to 0.8 mA for both sections, compared to the reference of 1.2 mA. Although the values are lower than the nominal references, the tube features an excellent internal balance, with a difference of just 2.1% in transconductance and identical anode currents. A particularly appreciable symmetry in applications requiring a good balance between the two sections.

The specimen passed 48 hours of burn-in and stability testing, maintaining a strong and even emission, without fluctuations, short circuits, or presence of gas. The tests also confirmed low noise and microphonics levels, making the tube suitable even for sensitive audio stages, including the V1 position in guitar amplifiers.

The 12AX7 / ECC83 General Electric tubes find application in hi-fi preamplifiers, compatible phono stages, and guitar amplifiers, both in the input stages and as drivers or phase inverters. American GE production is traditionally appreciated for a musical presentation generally described as clear, dynamic, and balanced, with good definition and expressive naturalness.

The value of this specimen lies in the authenticity of the American General Electric production, in the excellent electrical balance between the sections, and in the low-noise selection. The 188 marking identifies General Electric, while the dating code, not completely legible, does not allow us to establish the exact year of production. The good aesthetic condition, with partially preserved screen printing, completes the vintage character of an original GE 12AX7 / ECC83, tested and selected for those who want a vintage tube with documented performance and verified stability.

Condition:

• Condition: Vintage Tubes - Tested and perfectly functional. Supplied in our custom box for optimal protection.  
  
• Functionality: Perfectly operational.
  
• Aesthetic condition: Good – Lettering partially eroded, but still legible. Tube body in good condition. See photos for details.
  
• Manufacturing Code: ?? - 188 → two-letter code → Code not decipherable. Production attributable approximately to the 1970s based on construction features → General Electric Company, Syracuse 1, N. Y.

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