{"product_id":"6x4-ez90-nos-sylvania-black-plates-halo-getter-tested-rectifier-tube-usa-1952","title":"6X4 EZ90 NOS SYLVANIA Black Plates Halo Getter Tested Rectifier Tube USA 1952","description":"\u003cp\u003e\u003cstrong\u003e6X4 (EZ90) NOS SYLVANIA Black Plates Halo Getter Tested Rectifier Tube USA 1952\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eSound Description:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-start=\"157\" data-end=\"596\"\u003eThe Sylvania 6X4 (EZ90), produced in the United States in 1952, is a miniature rectifier that combines reliability and sonic refinement, thanks to its black-plate, halo-getter construction. This tested NOS version stands out for its quiet operation and its ability to provide a stable, musical power supply, ideal for vintage hi-fi equipment, tube tuners, and high-end preamplifiers.\u003c\/p\u003e\n\u003cp data-start=\"598\" data-end=\"628\"\u003e\u003cstrong data-start=\"600\" data-end=\"626\"\u003eSound characteristics\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli data-start=\"631\" data-end=\"725\"\u003e\u003cstrong data-start=\"631\" data-end=\"640\"\u003eBass\u003c\/strong\u003e : dry and compact, with solid control that gives authority to the low register.\u003c\/li\u003e\n\u003cli data-start=\"728\" data-end=\"838\"\u003e\u003cstrong data-start=\"728\" data-end=\"736\"\u003eMids\u003c\/strong\u003e : clear and natural, transparent and free from coloration, ideal for rendering voices with realism.\u003c\/li\u003e\n\u003cli data-start=\"841\" data-end=\"944\"\u003e\u003cstrong data-start=\"841\" data-end=\"849\"\u003eHighs\u003c\/strong\u003e : Smooth and airy, never fatiguing, with elegant detail that enriches the soundstage.\u003c\/li\u003e\n\u003cli data-start=\"947\" data-end=\"1060\"\u003e\u003cstrong data-start=\"947\" data-end=\"959\"\u003eDynamics\u003c\/strong\u003e : linear and responsive, capable of accurately following both rapid and more delicate passages.\u003c\/li\u003e\n\u003cli data-start=\"1063\" data-end=\"1167\"\u003e\u003cstrong data-start=\"1063\" data-end=\"1077\"\u003eSoundstage\u003c\/strong\u003e : Stable and focused, with a silent black background and a balanced soundstage.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1169\" data-end=\"1361\"\u003e🎧 \u003cstrong data-start=\"1172\" data-end=\"1188\"\u003eHi-Fi use\u003c\/strong\u003e\u003cbr data-start=\"1188\" data-end=\"1191\"\u003ePerfect for tube preamps and tuners, the Sylvania 6X4 ensures clean, consistent power, improving detail and transparency in your audio chain.\u003c\/p\u003e\n\u003cp data-start=\"1363\" data-end=\"1549\"\u003e🎸 \u003cstrong data-start=\"1366\" data-end=\"1398\"\u003eUse in Music Applications\u003c\/strong\u003e\u003cbr data-start=\"1398\" data-end=\"1401\"\u003eAlso suitable for vintage instrument amplifiers using EZ90\/6X4, it guarantees a warm and stable sound, with a natural harmonic output.\u003c\/p\u003e\n\u003cp data-start=\"1551\" data-end=\"1838\"\u003e🎯 \u003cstrong data-start=\"1554\" data-end=\"1592\"\u003eNote for audiophiles and collectors\u003c\/strong\u003e \u003cbr data-start=\"1592\" data-end=\"1595\"\u003eThis 1952 Sylvania 6X4 is a vintage model highly regarded for its robustness and quiet operation. In tested NOS condition, it's a solid choice for those who want to preserve the sonic authenticity of vintage equipment.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eValve tested on Funke W19 Tube Tester:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eTest Conditions:\u003c\/strong\u003e Va = 60V, Vf = 6.3V\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eAverage 100%:\u003c\/strong\u003e Ia =\u003cmeta charset=\"utf-8\"\u003e 42 mA\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eTest Result:\u003c\/strong\u003e VERY STRONG\u003cstrong\u003e\u003c\/strong\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eSection 1:\u003c\/strong\u003e Ia = 48 mA\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eSection 2:\u003c\/strong\u003e Ia = 48 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003cdiv\u003e\u003cstrong\u003eAdditional Tests Performed:\u003c\/strong\u003e\u003c\/div\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eMicrophonics:\u003c\/strong\u003e Very\u003cmeta charset=\"utf-8\"\u003e Low. Tested and approved for use in hi-fi and guitar amplifiers.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eOutput Quality:\u003c\/strong\u003e Excellent – Very strong and stable output, no fluctuations.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eShort circuits and GAS:\u003c\/strong\u003e Absent.\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr\u003e\n\u003ch3\u003e\u003cstrong\u003eConditions:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eCondition:\u003c\/strong\u003e NOS - New Old Stock - Tested and working - Supplied in our custom box for optimal protection.\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eFunctionality:\u003c\/strong\u003e Fully functional.\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eCosmetic condition:\u003c\/strong\u003e Excellent – Excellently preserved lettering, minimal signs of wear. See photos for details.\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eManufacturing Code:\u003c\/strong\u003e\u003cmeta charset=\"utf-8\"\u003e \u003cspan\u003e222 - 22nd week of 1952\u003c\/span\u003e\u003c\/li\u003e\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 durability\" href=\"https:\/\/vacuumtubestreasures.com\/blogs\/notizie\/perche-le-nostre-valvole-sono-diverse\" target=\"_blank\"\u003e\u003cstrong\u003eFind out why our valves are different →\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"SYLVANIA","offers":[{"title":"Default Title","offer_id":55490090238300,"sku":"03119","price":82.0,"currency_code":"PLN","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/2_62cecbd2-dbe5-4e79-8349-567d4a56d07c.jpg?v=1758040581","url":"https:\/\/vacuumtubestreasures.com\/en-pl\/products\/6x4-ez90-nos-sylvania-black-plates-halo-getter-tested-rectifier-tube-usa-1952","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}