{"product_id":"6sn7gta-nos-sylvania-chrome-top-matched-quad-same-production-code-low-noise-microphonics-amplitrex-tested","title":"6SN7GTA NOS SYLVANIA Chrome Top Matched Quad - 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 Quad – 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 #15\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = \u003cmeta charset=\"utf-8\"\u003e2600 ; Ia = 8.2 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2600 ; Ia = 8.0 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #22\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = 2500 ; Ia = 8.0 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2700 ; Ia = 8.4 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #5\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = 2600 ; Ia = 8.4 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = 2600 ; Ia = 8.2 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eTube #39\u003c\/b\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli class=\"p1\"\u003eSection 1: Gm = 2620 ; Ia = 8.6 mA\u003c\/li\u003e\n\n\u003cli class=\"p1\"\u003eSection 2: Gm = \u003cmeta charset=\"utf-8\"\u003e2600 ; Ia = 7.8 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 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 quad of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e6SN7GTA Sylvania\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, produced 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 Quad\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. All four 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 particularly desirable set for those seeking the authenticity and build quality of 1950s American Sylvania production.\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 an electrical matching of remarkable precision. The average transconductances of the four tubes are between \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e2600 and 2610 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, virtually coinciding with the nominal reference of 2600. Even more interesting is the uniformity of the average anode currents, concentrated in the range of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e8.1–8.3 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, compared to the reference of 9.0 mA. The individual sections feature transconductances between 2500 and 2700 µmhos and anode currents between 7.8 and 8.6 mA. An overall picture that confirms a \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003every well-matched Quad\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with small differences and particularly consistent electrical characteristics.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eAll four tubes passed \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e48 hours of burn-in and stability testing\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, maintaining a very strong and constant emission, without fluctuations, short circuits, or gas. Specific tests also confirmed very low noise and microphonic levels, with special \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eGreen Dot and Gray Dot\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e classification. A selection that takes on particular value in sensitive audio stages, where silence and stability are important requirements.\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, headphone amplifiers, driver stages, and compatible phase inverter circuits. The uniformity of this quad makes it particularly interesting for equipment requiring multiple tubes with homogeneous electrical characteristics. 1950s Sylvania production is also traditionally appreciated by audiophiles for a musical presentation that is \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003enatural, open, and well-articulated\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with a pleasant combination of definition and expressive richness.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe opportunity to bring together \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003efour authentic NOS Sylvania tubes from the same production week in March 1955\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with perfectly preserved original markings, excellent cosmetic condition, and such close electrical values, gives this quad particular interest. A carefully matched vintage set that combines \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003ehistorical authenticity, electrical uniformity, and verified reliability\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, intended for enthusiasts who wish to equip their audio system with original American tubes of documented quality.\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 perfectly 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 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":59658837721436,"sku":"03900","price":359.8,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/1_9bdc68a0-c003-4b91-b8d6-06233f808667.jpg?v=1793096855","url":"https:\/\/vacuumtubestreasures.com\/en-lu\/products\/6sn7gta-nos-sylvania-chrome-top-matched-quad-same-production-code-low-noise-microphonics-amplitrex-tested","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}