{"product_id":"6sn7gtb-nos-sylvania-chrome-top-green-dot-matched-pair-black-plates-tubes-usa-50s-4","title":"6SN7GTB NOS SYLVANIA CHROME TOP Green Dot Matched Pair Black Plates Tubes USA '50s","description":"\u003cp\u003e\u003cstrong\u003e6SN7GTB NOS SYLVANIA CHROME TOP Matched Pair Green Dot Black Plates Tubes – Same Codes – Made in USA '57\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eThis matched pair of\u003c\/strong\u003e \u003cstrong\u003e1957\u003c\/strong\u003e Sylvania 6SN7 GTB tubes, with \u003cstrong\u003eblack plates\u003c\/strong\u003e , \u003cstrong\u003echrome tops\u003c\/strong\u003e , \u003cstrong\u003egreen dot\u003c\/strong\u003e selector, and \u003cstrong\u003eidentical part numbers\u003c\/strong\u003e , represents one of the finest and most consistent NOS configurations in postwar American production. The \u003cem\u003egreen dot\u003c\/em\u003e was a factory-applied marking by Sylvania to identify tubes selected for \u003cstrong\u003elow noise and low microphony\u003c\/strong\u003e , intended for critical military, professional, and high-end audio applications. The build quality of this generation, combined with the accurate matching between the two tubes, makes it an excellent choice for \u003cstrong\u003estereo tube preamplifiers\u003c\/strong\u003e , \u003cstrong\u003edriver stages\u003c\/strong\u003e , and \u003cstrong\u003edual-mono configurations\u003c\/strong\u003e , where \u003cstrong\u003etonal consistency, quiet operation, and natural musicality\u003c\/strong\u003e are essential.\u003c\/p\u003e\n\u003cp\u003eThese valves are distinguished by a \u003cstrong\u003etransparent and three-dimensional voice\u003c\/strong\u003e , with a \u003cstrong\u003eneutral but musical\u003c\/strong\u003e character, capable of enhancing the microdynamics without forced colorations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eBass\u003c\/strong\u003e : tight and well-defined. The low range is \u003cstrong\u003earticulated, dry, and free of bloat\u003c\/strong\u003e , offering a \u003cstrong\u003econtrolled and stable\u003c\/strong\u003e harmonic foundation. Ideal for maintaining \u003cstrong\u003eclarity and precision\u003c\/strong\u003e in the lower registers, even with complex passages.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMids\u003c\/strong\u003e : Clear and natural. The midrange is \u003cstrong\u003ebalanced and free of artifacts\u003c\/strong\u003e , with \u003cstrong\u003ewell-focused vocals\u003c\/strong\u003e and a \u003cstrong\u003erealistic rendition of acoustic instruments\u003c\/strong\u003e . No artificial emphasis, but a \u003cstrong\u003econsistent transparency\u003c\/strong\u003e that promotes deep and engaging listening.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHighs\u003c\/strong\u003e : Fine and non-fatiguing. The high range is \u003cstrong\u003edelicate, extended and airy\u003c\/strong\u003e , with a \u003cstrong\u003ediscreet brilliance\u003c\/strong\u003e and \u003cstrong\u003edetail perfectly integrated into the musical fabric\u003c\/strong\u003e . Excellent for long listening sessions without fatigue.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDynamics\u003c\/strong\u003e : Fluid and modulated. The dynamic response is \u003cstrong\u003eprogressive\u003c\/strong\u003e , capable of \u003cstrong\u003enaturally conveying subtle nuances\u003c\/strong\u003e , but also of sustaining \u003cstrong\u003eenergetic passages\u003c\/strong\u003e without stiffening. The torque reacts \u003cstrong\u003equickly but in a controlled\u003c\/strong\u003e manner, ensuring constant musicality.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSoundstage\u003c\/strong\u003e : Wide and stable. The soundstage is \u003cstrong\u003ewide and deep\u003c\/strong\u003e , with \u003cstrong\u003eexcellent instrument placement\u003c\/strong\u003e and \u003cstrong\u003ecoherent layering\u003c\/strong\u003e . Identical matching and codes contribute to a \u003cstrong\u003eprecise, focused and relaxed\u003c\/strong\u003e stereo image.\u003c\/p\u003e\n\u003cp\u003e🎧 \u003cstrong\u003eUse in Hi-Fi Stereo Amplifiers\u003c\/strong\u003e \u003cbr\u003eThis \u003cstrong\u003ematched pair\u003c\/strong\u003e is ideal for preamp, driver, and mid-stage applications in high-quality stereo setups. It offers \u003cstrong\u003echannel-to-channel consistency, low noise, and refined tonal response\u003c\/strong\u003e , making it perfect for transparent, high-end systems, both modern and vintage.\u003c\/p\u003e\n\u003cp\u003e🎸 \u003cstrong\u003eUse in Instrument Amplifiers\u003c\/strong\u003e\u003cbr\u003eWhile not the primary choice for traditional guitar amps, the Sylvania Chrome Top 6SN7 GTB finds use in \u003cstrong\u003eboutique designs\u003c\/strong\u003e , \u003cstrong\u003ejazz guitar\u003c\/strong\u003e amps, and \u003cstrong\u003estudio-grade\u003c\/strong\u003e circuitry, where \u003cstrong\u003etransparency and harmonic control\u003c\/strong\u003e are preferred over over-the-top distortion.\u003c\/p\u003e\n\u003cp\u003e🎯 \u003cstrong\u003eNote for audiophiles and technicians\u003c\/strong\u003e \u003cbr\u003eA rare and valuable NOS selection, consisting of \u003cstrong\u003etwo perfectly matched, quiet and stable tubes\u003c\/strong\u003e , ideal for critical stereo stages, high-end restorations, and applications where \u003cstrong\u003eprecision and musicality\u003c\/strong\u003e must coexist. The combination of \u003cstrong\u003eblack plates, chrome top, and green dot selection\u003c\/strong\u003e is considered among the most successful of the 1950s Sylvania school.\u003c\/p\u003e\n\u003chr\u003e\n\u003cp data-end=\"3436\" data-start=\"3046\"\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eValves tested on \u003cstrong\u003eAmplitrex AT-1000 Tube tester\u003c\/strong\u003e :\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eTest Conditions:\u003c\/strong\u003e Va = 250V, Vg = -8V\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eAverage 100% Gm = 2600 ; Ia = 9.0 mA\u003c\/strong\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve #5:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2800 ; Ia = 9.0 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 2700 ; Ia = 8.8 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve #11:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2900 ; Ia = 8.6 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 2900 ; Ia = 9.4 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv\u003e\u003cstrong\u003eAdditional Tests Performed:\u003c\/strong\u003e\u003c\/div\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eMicrophonics and Noise\u003c\/strong\u003e : Very Low. Tested and approved for use in hi-fi, including phono stages and guitar amplifiers. Also suitable for V1.\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 \u003cspan\u003eExcellent – Excellently preserved lettering, minimal signs of wear. See photos for details.\u003c\/span\u003e\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eManufacturing Code:\u003cspan\u003e \u003c\/span\u003e\u003c\/strong\u003e166 718 - Manufactured by SYLVANIA USA - \u003cstrong data-start=\"336\" data-end=\"349\"\u003e166\u003c\/strong\u003e → customer EIA code (\u003cmeta charset=\"utf-8\"\u003e Chicago Electronic Engineering Company, Inc., Chicago 47, Ill. ) -\u003cmeta charset=\"utf-8\"\u003e \u003cstrong data-start=\"310\" data-end=\"317\"\u003e718\u003c\/strong\u003e → 18th week of 1957\u003c\/li\u003e\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 durability\" rel=\"noopener\" 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":56424859402588,"sku":"03345","price":183000.0,"currency_code":"KRW","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/8_6807079f-5be7-443c-b999-660740a681c6.jpg?v=1767978961","url":"https:\/\/vacuumtubestreasures.com\/en-kr\/products\/6sn7gtb-nos-sylvania-chrome-top-green-dot-matched-pair-black-plates-tubes-usa-50s-4","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}