{"product_id":"6sn7gtb-nos-sylvania-chrome-top-matched-quad-low-noise-mic-black-plates-tubes-usa-1955","title":"6SN7GTB NOS SYLVANIA CHROME TOP Matched Quad Yellow Dot Black Plates Tubes USA 1955","description":"\u003cp\u003e\u003cstrong\u003e6SN7GTB NOS SYLVANIA CHROME TOP Matched Quad Yellow\u003cmeta charset=\"utf-8\"\u003e Dot Black Plates Tubes - Same Codes - Made in USA '55\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-end=\"817\" data-start=\"245\"\u003e\u003cstrong data-end=\"290\" data-start=\"248\"\u003eThe matched quartet of\u003c\/strong\u003e \u003cstrong data-end=\"303\" data-start=\"295\"\u003e1955\u003c\/strong\u003e Sylvania 6SN7 GTBs, with \u003cstrong data-end=\"325\" data-start=\"309\"\u003eblack plates\u003c\/strong\u003e , \u003cstrong data-end=\"342\" data-start=\"327\"\u003echrome tops\u003c\/strong\u003e , \u003cstrong data-end=\"357\" data-start=\"344\"\u003eyellow dot\u003c\/strong\u003e selector, and \u003cstrong data-end=\"392\" data-start=\"373\"\u003eidentical part numbers\u003c\/strong\u003e , represents one of the finest and most consistent NOS configurations in postwar American production. The yellow 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-end=\"638\" data-start=\"608\"\u003etube preamplifiers\u003c\/strong\u003e , \u003cstrong data-end=\"684\" data-start=\"640\"\u003epush-pull amplifier driver stages\u003c\/strong\u003e , or \u003cstrong data-end=\"719\" data-start=\"688\"\u003ehigh-end dual mono restorations\u003c\/strong\u003e , where \u003cstrong data-end=\"785\" data-start=\"726\"\u003etonal consistency, quiet operation, and natural musicality\u003c\/strong\u003e are essential.\u003c\/p\u003e\n\u003cp data-end=\"1000\" data-start=\"819\"\u003eThese valves are distinguished by a \u003cstrong data-end=\"895\" data-start=\"857\"\u003etransparent and three-dimensional voice\u003c\/strong\u003e , with a \u003cstrong data-end=\"936\" data-start=\"914\"\u003eneutral but musical\u003c\/strong\u003e character, capable of enhancing the microdynamics without forced colorations.\u003c\/p\u003e\n\u003cp data-end=\"1270\" data-start=\"1007\"\u003e\u003cstrong data-end=\"1016\" data-start=\"1007\"\u003eBass\u003c\/strong\u003e : tight and well-defined. The low range is \u003cstrong data-end=\"1100\" data-start=\"1056\"\u003earticulated, dry, and free of bloat\u003c\/strong\u003e , offering a \u003cstrong data-end=\"1154\" data-start=\"1129\"\u003econtrolled and stable\u003c\/strong\u003e harmonic foundation. Perfect for maintaining \u003cstrong data-end=\"1205\" data-start=\"1179\"\u003eclarity and precision\u003c\/strong\u003e in the lower registers, even in complex passages.\u003c\/p\u003e\n\u003cp data-end=\"1546\" data-start=\"1272\"\u003e\u003cstrong data-end=\"1280\" data-start=\"1272\"\u003eMids\u003c\/strong\u003e : Clear and natural. The midrange is \u003cstrong data-end=\"1357\" data-start=\"1321\"\u003ebalanced and free of artifacts\u003c\/strong\u003e , with \u003cstrong data-end=\"1384\" data-start=\"1363\"\u003ewell-centered vocals\u003c\/strong\u003e and a \u003cstrong data-end=\"1435\" data-start=\"1396\"\u003erealistic rendition of acoustic instruments\u003c\/strong\u003e . There is no artificial emphasis, but a \u003cstrong data-end=\"1497\" data-start=\"1473\"\u003econsistent transparency\u003c\/strong\u003e that facilitates deep and engaging listening.\u003c\/p\u003e\n\u003cp data-end=\"1768\" data-start=\"1548\"\u003e\u003cstrong data-end=\"1556\" data-start=\"1548\"\u003eHighs\u003c\/strong\u003e : Fine and non-fatiguing. The high range is \u003cstrong data-end=\"1627\" data-start=\"1598\"\u003edelicate, extended and airy\u003c\/strong\u003e , with a \u003cstrong data-end=\"1662\" data-start=\"1637\"\u003ediscreet brilliance\u003c\/strong\u003e and \u003cstrong data-end=\"1716\" data-start=\"1668\"\u003edetail well integrated into the musical fabric\u003c\/strong\u003e . Excellent for long listening sessions without fatigue.\u003c\/p\u003e\n\u003cp data-end=\"2053\" data-start=\"1770\"\u003e\u003cstrong data-end=\"1782\" data-start=\"1770\"\u003eDynamics\u003c\/strong\u003e : Fluid and modulated. The dynamic response is \u003cstrong data-end=\"1841\" data-start=\"1826\"\u003eprogressive\u003c\/strong\u003e , capable of \u003cstrong data-end=\"1900\" data-start=\"1864\"\u003enaturally reproducing minimal nuances\u003c\/strong\u003e , but also of sustaining \u003cstrong data-end=\"1945\" data-start=\"1924\"\u003eenergetic passages\u003c\/strong\u003e without stiffening. The valves react \u003cstrong data-end=\"2020\" data-start=\"1995\"\u003equickly but in a controlled\u003c\/strong\u003e manner, ensuring constant musicality.\u003c\/p\u003e\n\u003cp data-end=\"2341\" data-start=\"2055\"\u003e\u003cstrong data-end=\"2069\" data-start=\"2055\"\u003eSoundstage\u003c\/strong\u003e : Wide and stable. The soundstage is \u003cstrong data-end=\"2126\" data-start=\"2106\"\u003ewide and deep\u003c\/strong\u003e , with \u003cstrong data-end=\"2173\" data-start=\"2132\"\u003eexcellent instrument placement\u003c\/strong\u003e and \u003cstrong data-end=\"2208\" data-start=\"2180\"\u003ecoherent layering\u003c\/strong\u003e . Coherence between channels, ensured by matching and identical codes, contributes to a \u003cstrong data-end=\"2340\" data-start=\"2317\"\u003eprecise and relaxed\u003c\/strong\u003e stereo image.\u003c\/p\u003e\n\u003cp data-end=\"2713\" data-start=\"2348\"\u003e🎧 \u003cstrong data-end=\"2398\" data-start=\"2351\"\u003eUse in Push-Pull Stereo Hi-Fi Amplifiers\u003c\/strong\u003e\u003cbr data-end=\"2401\" data-start=\"2398\"\u003eThis matched quartet is ideal for driver stages, mid-stages, or preamp power amps in high-quality stereo setups. It offers \u003cstrong data-end=\"2624\" data-start=\"2548\"\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-end=\"3044\" data-start=\"2715\"\u003e🎸 \u003cstrong data-end=\"2756\" data-start=\"2718\"\u003eUse in Instrument Amplifiers\u003c\/strong\u003e\u003cbr data-end=\"2759\" data-start=\"2756\"\u003eWhile not the primary choice for guitar amps, the Sylvania Chrome Top 6SN7 GTB finds its place in \u003cstrong data-end=\"2882\" data-start=\"2861\"\u003eboutique designs\u003c\/strong\u003e , \u003cstrong data-end=\"2911\" data-start=\"2894\"\u003ejazz guitar\u003c\/strong\u003e amps, or in \u003cstrong data-end=\"2948\" data-start=\"2932\"\u003estudio-grade\u003c\/strong\u003e circuits, where \u003cstrong data-end=\"3004\" data-start=\"2963\"\u003econtrolled harmonic output and transparency\u003c\/strong\u003e are preferred over driven distortion.\u003c\/p\u003e\n\u003cp data-end=\"3436\" data-start=\"3046\"\u003e🎯 \u003cstrong data-end=\"3081\" data-start=\"3049\"\u003eNote for audiophiles and technicians\u003c\/strong\u003e \u003cbr data-end=\"3084\" data-start=\"3081\"\u003eA rare and valuable NOS selection, with \u003cstrong data-end=\"3179\" data-start=\"3123\"\u003eperfectly matched, quiet and stable tubes\u003c\/strong\u003e , perfect for dual mono restorations, balanced stages and applications where \u003cstrong data-end=\"3278\" data-start=\"3251\"\u003eprecision and musicality\u003c\/strong\u003e must coexist. The combination of \u003cstrong data-end=\"3370\" data-start=\"3316\"\u003eblack plates, chrome top and yellow selection dot\u003c\/strong\u003e is considered among the most successful of the 1950s Sylvania school.\u003c\/p\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 1:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2400 ; Ia = 6.4 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm =\u003cmeta charset=\"utf-8\"\u003e 2500 ; Ia = 7.4 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve 2:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2500 ; Ia = 7.2 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm =\u003cmeta charset=\"utf-8\"\u003e 2400 ; Ia = 6.6 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve 3:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2500 ; Ia = 6.8 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm =\u003cmeta charset=\"utf-8\"\u003e 2400 ; Ia = 6.6 mA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eValve 4:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eSection 1: Gm = 2400 ; Ia = 6.6 mA\u003c\/li\u003e\n\u003cli\u003eSection 2: Gm = 2500 ; Ia = 7.0 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\u003cspan\u003e\u003cstrong\u003eMicrophonics:\u003c\/strong\u003e Standard. 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 \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\u003e411 526 Manufactured by SYLVANIA USA \u003cmeta charset=\"utf-8\"\u003e \u003cstrong data-start=\"336\" data-end=\"349\"\u003e411\u003c\/strong\u003e → EIA code of the client (\u003cmeta charset=\"utf-8\"\u003e Hardwick, Hindle, Inc., Newark 5, N. J) -\u003cmeta charset=\"utf-8\"\u003e \u003cstrong data-start=\"310\" data-end=\"317\"\u003e526\u003c\/strong\u003e → 26th week of 1955\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\n\u003cp\u003e\u0026nbsp;\u003c\/p\u003e","brand":"SYLVANIA","offers":[{"title":"Default Title","offer_id":55784132706652,"sku":"03218","price":199.0,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/1_a2b23128-d1a9-4b46-828d-87e7e42b9f2a.jpg?v=1761150337","url":"https:\/\/vacuumtubestreasures.com\/en-de\/products\/6sn7gtb-nos-sylvania-chrome-top-matched-quad-low-noise-mic-black-plates-tubes-usa-1955","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}