{"product_id":"6sn7gta-nos-sylvania-chrome-top-matched-pair-same-production-code-low-noise-microphonics-amplitrex-tested","title":"6SN7GTA NOS SYLVANIA Chrome Top Matched Pair - Same Production Code - Low Noise \u0026 Microphonics - AMPLITREX Tested","description":"\u003ch3 class=\"p1\"\u003e\u003cb\u003e6SN7GTA NOS SYLVANIA – \u003cmeta charset=\"utf-8\"\u003e \u003cspan\u003eShort \u003c\/span\u003e\u003cspan\u003eBase \u003c\/span\u003e\u003cspan\u003eChrome \u003c\/span\u003e\u003cspan\u003eTop\u003c\/span\u003e – Matched Pair – Same Data Codes – Made in USA 1955\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eAMPLITREX Tested – VERY STRONG – \u003cmeta charset=\"utf-8\"\u003e \u003cspan\u003eGreen Dot \u0026amp; Gray Dot \u003cmeta charset=\"utf-8\"\u003e– \u003c\/span\u003eLow Noise \u0026amp; Microphonics\u003c\/b\u003e\u003c\/p\u003e\n\u003ch3 data-start=\"3046\" data-end=\"3436\"\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eTubes tested on an \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 #36\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = \u003cmeta charset=\"utf-8\"\u003e2700 ; Ia = 7.6 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2600 ; Ia = 7.0 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #9\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = 2600 ; Ia = 7.6 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2700 ; Ia = 8.2 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003ch3 class=\"p1\"\u003e\u003cb\u003eAdditional Tests:\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003e\u003cspan class=\"s1\"\u003e\u003cb\u003eBurn-in \/ Stability Test:\u003c\/b\u003e 48h – OK\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cspan class=\"s1\"\u003e\u003cb\u003eMicrophonics and noise:\u003c\/b\u003e\u003c\/span\u003e Very Low. Tested and suitable 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 Very good. The sections are consistent and well-aligned, making the tube suitable for use as a phase inverter in hi-fi and instrument applications.\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\u003cb\u003eDescription\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp data-pm-slice=\"1 1 []\"\u003e\u003cspan\u003eExceptional NOS pair of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e6SN7GTA Sylvania\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, manufactured in the United States in \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1955\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and carefully selected as a \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eMatched Pair\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. Both specimens share the identical manufacturing code \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e288 \/ 513\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, traceable to the 13th week of 1955, and feature the characteristic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eShort Base Chrome Top\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e construction, a hallmark of Sylvania's renowned American production in the 1950s.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe measurements performed 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\u003e2600 and 2700 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with an average of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2650 µmhos for each tube\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, exceeding the nominal reference of 2600. The anode currents range from 7.0 to 8.2 mA, with averages of 7.3 and 7.9 mA respectively, compared to the 9.0 mA reference. Results that confirm a very strong transconductance and a \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eparticularly uniform match\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with well-balanced sections and minimal differences between the two specimens.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe selection includes \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e48 hours of burn-in\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, during which the stability of performance was verified, accompanied by tests that confirmed strong and constant emission, without short circuits or gas. Particular attention was paid to noise and microphonics, with very low results. The special \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eGreen Dot and Gray Dot\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e selection adds value to this pair, especially for use in the most sensitive audio stages.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e6SN7GTA Sylvania\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e tubes find application in hi-fi preamplifiers, driver stages, headphone amplifiers, and compatible phase inverter circuits. Sylvania production from this period is particularly appreciated by vintage tube enthusiasts for a musical presentation generally described as \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eopen, balanced, and rich in detail\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with an expressive naturalness that fuels interest in them within the world of tube audio.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eBelonging to the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003esame production week in March 1955\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, the excellently preserved original markings and excellent cosmetic condition make this pair particularly interesting from a historical perspective as well. An opportunity for those seeking authentic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1950s NOS Sylvania\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e tubes, with documented electrical characteristics, careful matching, and a selection designed to enhance their qualities in the most demanding audio applications.\u003c\/span\u003e\u003c\/p\u003e\n\u003chr\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 NOS - New Old Stock - Tested and working - 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 Excellent – Markings excellently preserved, minimal signs of age. See photos for details.\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003e\n\n\u003cmeta charset=\"utf-8\"\u003e \u003cstrong\u003eSpecial \u003c\/strong\u003e\u003cspan\u003e\u003cstrong\u003eselection:\u003c\/strong\u003e \u003c\/span\u003e\u003cstrong\u003e\u003cmeta charset=\"utf-8\"\u003e\u003c\/strong\u003e\u003cspan\u003eGreen \u003c\/span\u003e\u003cspan\u003eDot \u003c\/span\u003e\u003cspan\u003eand \u003c\/span\u003e\u003cspan\u003eGray \u003c\/span\u003e\u003cspan\u003eDot, \u003c\/span\u003e\u003cspan\u003ewith \u003c\/span\u003e\u003cspan\u003elow \u003c\/span\u003e\u003cspan\u003enoise \u003c\/span\u003e\u003cspan\u003eand \u003c\/span\u003e\u003cspan\u003emicrophonics \u003c\/span\u003e\u003cspan\u003everified \u003c\/span\u003e\u003cspan\u003eusing the \u003c\/span\u003e\u003cspan\u003eAmplitrex \u003c\/span\u003e\u003cspan\u003eAT-1000.\u003c\/span\u003e\n\n\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eManufacturing code:\u003c\/strong\u003e Sylvania Electric Products Inc., USA – original marking on the base 288 \/ 513. 288 Sylvania Internal code. 513 - 13th week of 1955 (March 1955).\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003ca rel=\"noopener\" title=\"Why our tubes are different – the VTT protocol that improves sound, reliability, and longevity\" href=\"https:\/\/vacuumtubestreasures.com\/blogs\/notizie\/perche-le-nostre-valvole-sono-diverse\" target=\"_blank\"\u003e\u003cstrong\u003eDiscover why our tubes are different →\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"SYLVANIA","offers":[{"title":"Default Title","offer_id":59667516391772,"sku":"03903","price":179.9,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/7_6148e448-9f4d-4bc2-80a1-fd5d3c63a857.jpg?v=1793178561","url":"https:\/\/vacuumtubestreasures.com\/en-gr\/products\/6sn7gta-nos-sylvania-chrome-top-matched-pair-same-production-code-low-noise-microphonics-amplitrex-tested","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}