{"product_id":"6sn7gtb-nos-sylvania-chrome-top-green-dot-matched-quad-black-plates-tubes-usa-1955","title":"6SN7GTB NOS SYLVANIA CHROME TOP Green Dot Matched Quad Black Plates Tubes USA '50s","description":"\u003cp\u003e\u003cstrong\u003e6SN7GTB NOS SYLVANIA CHROME TOP Matched Quad Green\u003cmeta charset=\"utf-8\"\u003e Dot Black Plates Tubes - Same Codes - Made in USA '57\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-start=\"245\" data-end=\"817\"\u003e\u003cstrong data-start=\"248\" data-end=\"290\"\u003eThe matched quartet of\u003c\/strong\u003e \u003cstrong data-start=\"295\" data-end=\"303\"\u003e1957\u003c\/strong\u003e Sylvania 6SN7 GTBs, with \u003cstrong data-start=\"309\" data-end=\"325\"\u003eblack plates\u003c\/strong\u003e , \u003cstrong data-start=\"327\" data-end=\"342\"\u003echrome tops\u003c\/strong\u003e , \u003cstrong data-start=\"344\" data-end=\"357\"\u003egreen dot\u003c\/strong\u003e selector, and \u003cstrong data-start=\"373\" data-end=\"392\"\u003eidentical part numbers\u003c\/strong\u003e , represents one of the finest and most consistent NOS configurations in postwar American production. The green dot was a factory-applied marking by Sylvania to identify tubes selected for low noise and microphony, intended for critical military, professional, and high-end audio applications. This generation’s build quality, combined with accurate matching, makes them an excellent choice for \u003cstrong data-start=\"608\" data-end=\"638\"\u003etube preamplifiers\u003c\/strong\u003e , \u003cstrong data-start=\"640\" data-end=\"684\"\u003epush-pull amplifier driver stages\u003c\/strong\u003e , or \u003cstrong data-start=\"688\" data-end=\"719\"\u003ehigh-end dual mono restorations\u003c\/strong\u003e , where \u003cstrong data-start=\"726\" data-end=\"785\"\u003etonal consistency, quietness, and natural musicality\u003c\/strong\u003e are essential.\u003c\/p\u003e\n\u003cp data-start=\"819\" data-end=\"1000\"\u003eThese valves are distinguished by a \u003cstrong data-start=\"857\" data-end=\"895\"\u003etransparent and three-dimensional voice\u003c\/strong\u003e , with a \u003cstrong data-start=\"914\" data-end=\"936\"\u003eneutral but musical\u003c\/strong\u003e character, capable of enhancing the microdynamics without forced colorations.\u003c\/p\u003e\n\u003cp data-start=\"1007\" data-end=\"1270\"\u003e\u003cstrong data-start=\"1007\" data-end=\"1016\"\u003eBass\u003c\/strong\u003e : tight and well-defined. The low range is \u003cstrong data-start=\"1056\" data-end=\"1100\"\u003earticulated, dry, and free of bloat\u003c\/strong\u003e , offering a \u003cstrong data-start=\"1129\" data-end=\"1154\"\u003econtrolled and stable\u003c\/strong\u003e harmonic foundation. Perfect for maintaining \u003cstrong data-start=\"1179\" data-end=\"1205\"\u003eclarity and precision\u003c\/strong\u003e in the lower registers, even in complex passages.\u003c\/p\u003e\n\u003cp data-start=\"1272\" data-end=\"1546\"\u003e\u003cstrong data-start=\"1272\" data-end=\"1280\"\u003eMids\u003c\/strong\u003e : Clear and natural. The midrange is \u003cstrong data-start=\"1321\" data-end=\"1357\"\u003ebalanced and free of artifacts\u003c\/strong\u003e , with \u003cstrong data-start=\"1363\" data-end=\"1384\"\u003ewell-centered vocals\u003c\/strong\u003e and a \u003cstrong data-start=\"1396\" data-end=\"1435\"\u003erealistic rendition of acoustic instruments\u003c\/strong\u003e . There is no artificial emphasis, but a \u003cstrong data-start=\"1473\" data-end=\"1497\"\u003econsistent transparency\u003c\/strong\u003e that facilitates deep and engaging listening.\u003c\/p\u003e\n\u003cp data-start=\"1548\" data-end=\"1768\"\u003e\u003cstrong data-start=\"1548\" data-end=\"1556\"\u003eHighs\u003c\/strong\u003e : Fine and non-fatiguing. The high range is \u003cstrong data-start=\"1598\" data-end=\"1627\"\u003edelicate, extended and airy\u003c\/strong\u003e , with a \u003cstrong data-start=\"1637\" data-end=\"1662\"\u003ediscreet brilliance\u003c\/strong\u003e and \u003cstrong data-start=\"1668\" data-end=\"1716\"\u003edetail well integrated into the musical fabric\u003c\/strong\u003e . Excellent for long listening sessions without fatigue.\u003c\/p\u003e\n\u003cp data-start=\"1770\" data-end=\"2053\"\u003e\u003cstrong data-start=\"1770\" data-end=\"1782\"\u003eDynamics\u003c\/strong\u003e : Fluid and modulated. The dynamic response is \u003cstrong data-start=\"1826\" data-end=\"1841\"\u003eprogressive\u003c\/strong\u003e , capable of \u003cstrong data-start=\"1864\" data-end=\"1900\"\u003enaturally reproducing minimal nuances\u003c\/strong\u003e , but also of sustaining \u003cstrong data-start=\"1924\" data-end=\"1945\"\u003eenergetic passages\u003c\/strong\u003e without stiffening. The valves react \u003cstrong data-start=\"1995\" data-end=\"2020\"\u003equickly but in a controlled\u003c\/strong\u003e manner, ensuring constant musicality.\u003c\/p\u003e\n\u003cp data-start=\"2055\" data-end=\"2341\"\u003e\u003cstrong data-start=\"2055\" data-end=\"2069\"\u003eSoundstage\u003c\/strong\u003e : Wide and stable. The soundstage is \u003cstrong data-start=\"2106\" data-end=\"2126\"\u003ewide and deep\u003c\/strong\u003e , with \u003cstrong data-start=\"2132\" data-end=\"2173\"\u003eexcellent instrument placement\u003c\/strong\u003e and \u003cstrong data-start=\"2180\" data-end=\"2208\"\u003ecoherent layering\u003c\/strong\u003e . Coherence between channels, ensured by matching and identical codes, contributes to a \u003cstrong data-start=\"2317\" data-end=\"2340\"\u003eprecise and relaxed\u003c\/strong\u003e stereo image.\u003c\/p\u003e\n\u003cp data-start=\"2348\" data-end=\"2713\"\u003e🎧 \u003cstrong data-start=\"2351\" data-end=\"2398\"\u003eUse in Push-Pull Stereo Hi-Fi Amplifiers\u003c\/strong\u003e\u003cbr data-start=\"2398\" data-end=\"2401\"\u003eThis matched quartet is ideal for driver stages, mid-stages, or preamp power amps in high-quality stereo setups. It offers \u003cstrong data-start=\"2548\" data-end=\"2624\"\u003echannel-to-channel uniformity, 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 data-start=\"2715\" data-end=\"3044\"\u003e🎸 \u003cstrong data-start=\"2718\" data-end=\"2756\"\u003eUse in Instrument Amplifiers\u003c\/strong\u003e\u003cbr data-start=\"2756\" data-end=\"2759\"\u003eWhile not the primary choice for guitar amps, the Sylvania Chrome Top 6SN7 GTB finds its place in \u003cstrong data-start=\"2861\" data-end=\"2882\"\u003eboutique designs\u003c\/strong\u003e , \u003cstrong data-start=\"2894\" data-end=\"2911\"\u003ejazz guitar\u003c\/strong\u003e amps, or in \u003cstrong data-start=\"2932\" data-end=\"2948\"\u003estudio-grade\u003c\/strong\u003e circuits, where \u003cstrong data-start=\"2963\" data-end=\"3004\"\u003econtrolled harmonic output and transparency\u003c\/strong\u003e are preferred over driven distortion.\u003c\/p\u003e\n\u003cp data-start=\"3046\" data-end=\"3436\"\u003e🎯 \u003cstrong data-start=\"3049\" data-end=\"3081\"\u003eNote for audiophiles and technicians\u003c\/strong\u003e \u003cbr data-start=\"3081\" data-end=\"3084\"\u003eA rare and valuable NOS selection, with \u003cstrong data-start=\"3123\" data-end=\"3179\"\u003eperfectly matched, quiet and stable tubes\u003c\/strong\u003e , perfect for dual mono restorations, balanced stages and applications where \u003cstrong data-start=\"3251\" data-end=\"3278\"\u003eprecision and musicality\u003c\/strong\u003e must coexist. The combination of \u003cstrong data-start=\"3316\" data-end=\"3370\"\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\u003cp data-start=\"3046\" data-end=\"3436\"\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 #10:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 3000 ; Ia = 10.2 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 2900 ; Ia = 9.8 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve #12:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2900 ; Ia = 10.0 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 3000 ; Ia = 10.0 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve #8:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2900 ; Ia = 10.2 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 3000 ; Ia = 10.4 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve #9:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 3000 ; Ia = 11.4 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 722 - Manufactured by SYLVANIA USA - \u003cstrong data-end=\"349\" data-start=\"336\"\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-end=\"317\" data-start=\"310\"\u003e722\u003c\/strong\u003e → 22nd week of 1957\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":56250585383260,"sku":"03315","price":199.0,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/1_446eb53f-36a3-4373-9c1e-7bf6e2bad0f1.jpg?v=1765900564","url":"https:\/\/vacuumtubestreasures.com\/en-hr\/products\/6sn7gtb-nos-sylvania-chrome-top-green-dot-matched-quad-black-plates-tubes-usa-1955","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}