12AX7 / ECC83 NOS Heinz & Kauffman – Gray Plates – Foil Dimpled Getter – Made in USA – AMPLITREX Tested
Description:
This NOS 12AX7 / ECC83 marked Heinz & Kauffman , made in the USA in the 1950s , belongs to the tradition of American signal tubes made to very high construction standards.
The Heinz & Kauffman brand was used by a well-known American distributor who selected and rebranded valves produced by major American factories of the time. The available examples feature internal construction typical of 1950s American production, characterized by meticulous mechanical engineering and high-quality materials.
The internal structure includes:
- Gray Plates
- Foil Dimpled Getter
- robust construction typical of American productions of the period
The valve is in showcase aesthetic condition , with well-preserved silkscreen prints and a perfectly intact internal structure.
It has been individually tested in our laboratory with AMPLITREX AT-1000 , checking emission, stability and operational behavior.
Sound Characteristics
The American 12AX7s from the 1950s are known for a balanced, natural and very musical sound presentation.
Bass: Precise and well-controlled. The low range maintains good depth without losing definition.
Mids: Rich and natural. Vocals sound very believable, and instruments like piano, strings, and acoustic guitar emerge with excellent harmonic balance.
Highs: Clean and well-extended. The high end maintains a fine grain that promotes smooth, natural listening.
Dynamics: Very responsive. The tube precisely follows the variations in the musical signal while maintaining good microdynamics.
Soundstage: Stable and well-organized soundstage, with natural separation of instruments.
🎧 Use in Hi-Fi Stereo Amplifiers
The 12AX7 / ECC83 is one of the most popular signal tubes in audio equipment design.
It is used in:
- tube preamplifiers
- phono stages
- amplifier drivers
- integrated amplifiers and vintage equipment
Thanks to its low microphonics and low noise , this specimen is also suitable for sensitive circuit positions , where stability and quietness are particularly important.
🎸 Use in Music Amplifiers
The ECC83/12AX7 is one of the most widely used tubes in musical instrument amplifiers.
Vintage American valves generally offer:
- excellent midrange definition
- good dynamic response
- great touch sensitivity
Qualities that allow for an articulate and musical sound in guitar circuits.
🎯 Note for audiophiles and technicians
- Heinz & Kauffman – USA production 1950s
- 12AX7 / ECC83 NOS
- Gray Plates – Foil Dimpled Getter
- Showcase aesthetic conditions
- AMPLITREX AT-1000 Tested
- Low Noise & Microphonics
- Rating: VERY STRONG
A vintage American signal tube , built to the quality standards of 1950s production, capable of offering operational stability, silence and a natural and balanced sound presentation , qualities that continue to make it highly appreciated by audiophiles, technicians and musicians .
Test Results:
Valve tested on AMPLITREX AT-1000 Tube Tester:
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Test Conditions: Va = 250V ; Vg = -2V
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Average 100%: Gm = 1600 ; Ia = 1.2 mA
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Test Result: STRONG
Valve:
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Section 1: Gm = 1600 ; Ia = 1.3 mA
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Section 2: Gm = 1500 ; Ia = 1.1 mA
Additional Tests Performed:
- Microphonics: Low. Tested and approved for use in hi-fi, phono stages, and guitar amplifiers, including V1.
- Balance: The two sections show coherent and well-aligned values, making the valve also ideal as a phase inverter in hi-fi and instrumental applications.
- Output Quality: Excellent – Very strong and stable output, no fluctuations.
- Short circuits and GAS: Absent.
Conditions:
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Condition: NOS - New Old Stock - Tested and working - Supplied in our custom box for optimal protection.
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Functionality: Fully functional.
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Cosmetic condition: Excellent – Excellently preserved lettering, minimal signs of wear. See photos for details.
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Manufacturing Code: Unreadable – Made in the USA, identifiable by construction features. 1950s
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