6SN7GT RCA Radiotron Matched Pair Silver Logo Black Plates D Getter AMPLITREX Tested Low Noise & Mic Tubes

6SN7GT RCA Radiotron Matched Pair Silver Logo Black Plates D Getter - Made In USA - 1950s AMPLITREX Tested – VERY STRONG – Low Noise & Microphonics – Vintage American RCA Production Test Results: Tubes tested on Amplitrex AT-1000 Tube tester: Test Conditions: Va = 250V, Vg = -8V Average 100% Gm = 2600 ; Ia = 9.0 mA Test Result: VERY STRONG Tube #1 Section 1: Gm = 2500 ; Ia = 8.2 mA Section 2: Gm = 2500 ; Ia = 7.8 mA Tube #2 Section 1: Gm = 2600 ; Ia = 7.6 mA Section 2: Gm = 2300 ; Ia = 8.0 mA Description Interesting vintage pair of 6SN7GT RCA Radiotron, produced in the United States in the 1950s and carefully selected as a Matched Pair. Both specimens feature the characteristic Black Plates with D Getter construction, a configuration particularly appreciated in American RCA production. The famous silver RCA Radiotron screen printing, still clearly visible on one of the specimens, recalls the charm of the original tubes from this period. The manufacturing markings date the pair to 1954, with a completely legible date on one tube and partially preserved on the other. The measurements performed with the Amplitrex AT-1000 confirm overall well-matched electrical characteristics. The transconductance of the four sections ranges between 2300 and 2600 µmhos, with averages of 2500 and 2450 µmhos for the respective tubes, close to the nominal reference of 2600. The anode currents range from 7.6 to 8.2 mA, with averages of 8.0 and 7.8 mA, compared to the reference of 9.0 mA. Although there are some differences between the individual sections, the pair shows a good overall match, particularly evident in the closeness of the average anode currents. Both tubes have been carefully checked for emission stability, noise, and microphonics, with results confirming strong and stable emission, low noise levels, and no shorts or gas. Important checks to assess the actual condition of used vintage tubes and select reliable specimens for even sensitive audio applications. The 6SN7GT RCA Black Plates find use in hi-fi preamplifiers, headphone amplifiers, driver stages, and compatible phase inverter circuits. This American production is traditionally appreciated by audiophiles for a musical presentation generally described as full-bodied, natural, and rich in nuances, with an expressive midrange and balanced reproduction, characteristics that continue to fuel interest in tube listening. The charm of this pair lies in its historical authenticity and 1950s RCA construction, accompanied by documented electrical characteristics. The different conditions of the screen printing and signs of use testify to the history of these specimens, without compromising their verified functionality. A carefully selected vintage RCA Radiotron pair, interesting for enthusiasts who wish to rediscover original American production through tested tubes ready for new use. Additional Tests: Microphonics and noise: Low. Tested and suitable for use in hi-fi equipment and guitar amplifiers, even in the most sensitive audio stages. Balance: Good. The sections show a consistent balance, fully compatible with use in hi-fi and musical amplifiers, in all applications where absolute symmetry between sections is not required. Emission: Excellent – Very strong and stable emission, without fluctuations. Shorts / Gas: absent Condition Condition: Vintage Tubes - Tested and perfectly functional. Supplied in our custom box for optimal protection. Functionality: Perfectly operational Aesthetic condition: One tube in sufficient condition, with the screen printing almost completely absent and obvious signs of use, the other in Good condition – Partially eroded lettering, but still legible. Tube body in good condition. See photos for details. Manufacturing codes: 4-0? 274 → RMA/EIA Open Date Code → manufactured in the ??th week of 1954 - 274 → Radio Corporation of America, Camden, N. J. 4-09 → RMA/EIA Open Date Code → manufactured in the 9th week of 1954 - by Radio Corporation of America, Camden, N. J. Discover why our tubes are different →