6SN7GT SYLVANIA Metal Base Tall Bottle Black T-Plates Chrome Top - Made in USA '47

6SN7GT SYLVANIA Metal Base Tall Bottle Black T‑Plates Chrome Top - Made in USA '47 AMPLITREX Tested – STRONG – Low Noise & Microphonics Test Results: Tubes tested on an Amplitrex AT-1000 Tube tester: Test Conditions: Va = 250V, Vg = -8V Average 100% Gm = 2600 ; Ia = 9.0 mA Test Result: STRONG Tube Section 1: Gm = 1900 ; Ia = 7.2 mA Section 2: Gm = 2100 ; Ia = 7.0 mA Additional Tests: Microphonics and noise: Low. Tested and compliant for use in hi-fi equipment and guitar amplifiers, even in the most sensitive audio stages. Balance: Very good. The sections are consistent and well-matched, making the tube suitable for use as a phase inverter in hi-fi and instrumental applications. Emission: Strong – Strong and steady emission, suitable for any application. Shorts / Gas: none Description Rare US-made 6SN7GT Sylvania, manufactured in the 52nd week of 1947 and featuring the prestigious metal base, Tall Bottle, Black T‑Plates, and Chrome Top configuration. An instantly recognizable construction, belonging to the early Sylvania productions and highly sought after for its historical interest, build quality, and reputation in audio applications. The code 752 identifies a Sylvania production from the 52nd week of 1947. The green markings are excellently preserved and allow for full appreciation of the tube's original aesthetics, including the distinctive metal base with the classic Sylvania logo. The tube has been carefully measured with an Amplitrex AT‑1000. The two sections recorded Gm 1900 / Ia 7.2 mA and Gm 2100 / Ia 7.0 mA respectively, confirming strong and steady emission. The plate currents are very close, and the transconductance maintains good overall consistency, offering very good balance for a vintage tube of this era. The test also confirmed low noise and microphonics, as well as an absence of gas or shorts. It is therefore recommended for hi-fi preamplifiers, headphone amplifiers, driver stages, and guitar amplifiers, even in the most sensitive audio positions. The good alignment of the sections also allows for its use as a phase inverter in applications that do not require absolute symmetry. In terms of sound, early 6SN7GT Sylvania tubes with T‑Plates are appreciated for an open, fast, and natural presentation, with a well-focused midrange, detailed highs, and articulated, controlled low frequencies. The reproduction maintains notable liveliness without sacrificing musicality, favoring definition, instrument separation, and a wide, organized soundstage. An exceptional offering for those desiring an authentic 1947 Sylvania in the rare Metal Base version, with Tall Bottle, Black T‑Plates, and Chrome Top: a cosmetically well-preserved specimen, carefully tested and ready to enhance quality audio equipment. Condition Condition: Vintage tube - Tested and perfectly functional. Supplied in our custom box for optimal protection. Functionality: Perfectly operational Cosmetic condition: Excellent – Markings excellently preserved, minimal signs of aging. See photos for details. Manufacturing code: Manufacturer Sylvania Electric Products Inc., Emporium, Pa. - 752 → 7 (from three digits) → 1947 - 52 → 52nd week of the year Discover why our tubes are different →