{"product_id":"6sn7gt-vt-231-rca-radiotron-smoked-glass-matched-pair-silver-logo-black-plates-foil-getter-amplitrex-tested-low-noise-tubes","title":"6SN7GT \/ VT-231 RCA Radiotron Smoked Glass Matched Pair Silver Logo Black Plates Foil Getter AMPLITREX Tested Low Noise Tubes","description":"\u003ch3 class=\"p1\"\u003e\u003cstrong\u003e6SN7GT \/ VT-231 RCA Radiotron Smoked Glass Matched Pair Silver Logo Black Plates Foil Getter -  Made In USA - 1940s\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eAMPLITREX Tested – VERY STRONG – Low Noise \u0026amp; Microphonics\u003c\/b\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eTubes tested on \u003cstrong\u003eAmplitrex AT-1000 Tube tester\u003c\/strong\u003e:\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eTest Conditions:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eVa = 250V, Vg = -8V\u003c\/li\u003e\n\n\u003cli\u003e\u003cstrong\u003eAverage 100% Gm = 2600 ; Ia = 9.0 mA\u003c\/strong\u003e\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eTest Result:\u003c\/strong\u003e VERY STRONG\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #1\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 1: \u003c\/strong\u003eGm = 2600 ; Ia = 9.6 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 2: \u003c\/strong\u003eGm = 2500 ; Ia = 8.0 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #2\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 1: \u003c\/strong\u003eGm = 2400 ; Ia = 7.2 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 2: \u003c\/strong\u003eGm = 2500 ; Ia = 8.3 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003ch3 class=\"p1\"\u003e\u003cb\u003eDescription\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp data-pm-slice=\"1 1 []\"\u003e\u003cspan\u003eExtremely rare vintage pair of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e6SN7GT RCA Radiotron Smoked Glass\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, made in the United States and carefully selected as a \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eMatched Pair\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. The set includes one \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eJAN CRC-6SN7GT \/ VT-231\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and one \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eJAN 6SN7GT\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, both featuring the same construction configuration: \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eBlack Plates with Foil Getter and smoked glass\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. This particular RCA version, now difficult to find, is among the most sought after by enthusiasts of early American 6SN7GT tubes. The original military markings and unmistakable internal architecture attest to its authenticity and historical appeal.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eMeasurements taken with the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eAmplitrex AT-1000\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e show a transconductance between \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2400 and 2600 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with averages of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2550 and 2450 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e for the respective tubes, close to the nominal reference of 2600. The anode currents range from 7.2 to 9.6 mA, with averages of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e8.8 and 7.75 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e respectively, compared to the reference of 9.0 mA. The results confirm good consistency of the average transconductances, while highlighting some differences in anode currents and the balance of the individual sections.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eBoth tubes have been subjected to careful instrumental checks that confirmed \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003every strong and stable emission\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, without fluctuations, short circuits, or gas presence. Noise and microphonics checks also yielded low results, an aspect that is particularly important for vintage tubes of this type, also intended for sensitive audio applications.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e6SN7GT RCA Black Plates Smoked Glass\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e are particularly appreciated in headphone amplifiers, hi-fi preamplifiers, and compatible driver stages. Historic RCA productions with black plates have traditionally been sought by audiophiles for a musical presentation generally described as \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003efull-bodied, refined, and natural\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with a rich midrange full of nuances, a pleasant expressive depth, and an engaging musical reproduction.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe value of this \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eextremely rare RCA pair\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e lies above all in the particular construction \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eSmoked Glass with Black Plates and Foil Getter\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, shared by both specimens. Although the different manufacturing markings, \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e7-52 and H3E\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, do not allow us to establish with certainty that the two tubes belong to the same year of production, their \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003econstruction characteristics are consistent\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, from the structure of the plates to the configuration of the getter. Two authentic vintage American tubes, with original markings, very good cosmetic condition, and documented electrical characteristics. A combination of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003erarity, historical authenticity, and instrumental selection\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, intended for enthusiasts who wish to own and use one of the most fascinating creations of the RCA thermionic tradition.\u003c\/span\u003e\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3 class=\"p1\"\u003e\u003cb\u003eAdditional tests:\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eMicrophonics and noise:\u003c\/b\u003e\u003c\/span\u003e Low. Tested and compliant for use in hi-fi equipment and guitar amplifiers, including the most sensitive audio stages.\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eBalance:\u003c\/b\u003e\u003c\/span\u003e Good. The sections show a consistent balance, fully compatible with use in hi-fi and musical amplifiers, in all applications where absolute symmetry between the sections is not required.\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eEmission:\u003c\/b\u003e\u003c\/span\u003e Excellent – Very strong and stable emission, without fluctuations.\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cb\u003eShort circuits \/ Gas:\u003c\/b\u003e\u003cspan class=\"s1\"\u003e absent\u003c\/span\u003e\n\n\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003ch3 class=\"p1\"\u003e\u003cstrong\u003eCondition\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eCondition:\u003c\/b\u003e\u003c\/span\u003e Vintage Tubes - Tested and perfectly functioning. Supplied in our custom box for optimal protection.\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eFunctionality:\u003c\/b\u003e\u003c\/span\u003e Perfectly operational\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eCosmetic condition:\u003c\/b\u003e\u003c\/span\u003e Very Good – Markings clearly legible with slight signs of age. See photos for details.\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eManufacturing code:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e7-52 → RMA\/EIA Open Date Code → manufactured in the 52nd week of 1957 - by Radio Corporation of America, Camden, N. J.\u003c\/li\u003e\n\n\u003cli\u003eH3E \u003cmeta charset=\"utf-8\"\u003e→ Undecipherable code. Production can be attributed approximately to the 1940s based on construction characteristics. The vintage construction, with black plates, bottom foil getter, and smoked glass, is fully consistent with this period.\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003ca href=\"https:\/\/vacuumtubestreasures.com\/blogs\/notizie\/perche-le-nostre-valvole-sono-diverse\" title=\"Why our tubes are different – the VTT protocol that improves sound, reliability, and longevity\" rel=\"noopener\" target=\"_blank\"\u003e\u003cstrong\u003eDiscover why our tubes are different →\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"RCA","offers":[{"title":"Default Title","offer_id":59734723428700,"sku":"03909","price":199.9,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/2_1d173bd7-095c-4e31-b537-f6a7b9ef4ce4.jpg?v=1793630381","url":"https:\/\/vacuumtubestreasures.com\/en-hr\/products\/6sn7gt-vt-231-rca-radiotron-smoked-glass-matched-pair-silver-logo-black-plates-foil-getter-amplitrex-tested-low-noise-tubes","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}