{"product_id":"6sn7gta-nos-sylvania-chrome-top-matched-pair-same-production-code-low-noise-microphonics-amplitrex-tested-1","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 #31\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = 2600 ; Ia = 8.0 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2600 ; Ia = 7.8 mA\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 class=\"p1\"\u003eSection 1: Gm = 2600 ; Ia = 8.0 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2680 ; Ia = 9.0 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-matched, 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 none\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 tubes share the identical manufacturing code \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e288 \/ 513\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, dating back 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 particularly interesting combination for those seeking original American-made Sylvania tubes from the 1950s, with documented construction identity and manufacturing origin.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe measurements performed with an \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eAmplitrex AT-1000\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e highlight a particularly accurate match. The transconductance of the four sections ranges from \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2600 to 2680 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with averages of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2600 and 2640 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e for the two tubes, perfectly in line with or above the nominal reference of 2600. The anode currents range from 7.8 to 9.0 mA, with averages of 7.9 and 8.5 mA, respectively. The remarkable uniformity of the transconductance, accompanied by a good current balance, confirms the quality of the match and the electrical consistency of the pair.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eBoth tubes passed \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e48 hours of burn-in and stability testing\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, demonstrating very strong and constant emission, without fluctuations, short circuits, or gas. Noise and microphonics checks yielded very low results, allowing for the special \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eGreen Dot and Gray Dot\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e classification. A particularly significant selection for audiophiles seeking reliable tubes even in the most sensitive amplification 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 are appreciated for use in hi-fi preamplifiers, headphone amplifiers, driver stages, and compatible phase inverter circuits. Sylvania production from this period is traditionally sought after by enthusiasts for a musical reproduction generally described as \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003enatural, airy, and well-articulated\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, capable of combining definition and listening pleasure.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003esame production week in March 1955\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, the excellent preservation of the original markings, and the particularly well-maintained cosmetic condition complete the value of this pair. Two authentic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003evintage NOS Sylvania\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e tubes, united by their manufacturing origin and selected to offer uniform electrical characteristics, verified stability, and extremely low noise: a choice of particular interest for those who wish to enhance their audio system with original American tubes from the 1950s.\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 optimally 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 an \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 is the internal Sylvania 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":59667961708892,"sku":"03904","price":639.0,"currency_code":"ILS","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/6_75eaaea7-2fdd-4854-af03-faa0ef4e3d59.jpg?v=1793183106","url":"https:\/\/vacuumtubestreasures.com\/en-il\/products\/6sn7gta-nos-sylvania-chrome-top-matched-pair-same-production-code-low-noise-microphonics-amplitrex-tested-1","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}