{"product_id":"5693-cv3699-rca-nos-special-red-amplitrex-matched-pair-tubes-made-in-usa-52","title":"5693 ( CV3699 ) RCA NOS SPECIAL RED AMPLITREX Matched Pair Tubes MADE IN USA '52","description":"\u003cp class=\"p1\"\u003e\u003cstrong\u003e5693 ( CV3699 ) RCA NOS SPECIAL RED Matched Pair Tubes MADE IN USA '52\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eAMPLITREX Tested – VERY STRONG\u003c\/b\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eGeneral Description\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eThis extraordinary \u003cspan class=\"s1\"\u003e\u003cb\u003epair of 5693 (CV3699) RCA NOS \"Special Red\"\u003c\/b\u003e\u003c\/span\u003e tubes, manufactured in the United States in \u003cspan class=\"s1\"\u003e\u003cb\u003eMarch 1952 (same date codes 3-52)\u003c\/b\u003e\u003c\/span\u003e, represents one of the most iconic and sought-after versions of the 6SL7 family.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe \u003cspan class=\"s1\"\u003e\u003cb\u003e5693 Special Red\u003c\/b\u003e\u003c\/span\u003e series is universally recognized for its selected construction and superior quality standards compared to standard versions. The characteristic \u003cspan class=\"s1\"\u003e\u003cb\u003ered coating\u003c\/b\u003e\u003c\/span\u003e is not only a distinctive aesthetic element but identifies a special production, designed to ensure greater stability, durability, and reliability over time.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThis pair stands out for:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eRCA USA – 1950s production\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003e5693 \/ CV3699 – selected special version\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003e\"Special Red\" body\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eSame Date Codes 3-52\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eMatched Pair NOS\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003eThis is an \u003cspan class=\"s1\"\u003e\u003cb\u003eNOS matched pair, tested and perfectly consistent\u003c\/b\u003e\u003c\/span\u003e, with \u003cspan class=\"s1\"\u003e\u003cb\u003eperfectly matching electrical values between the two units\u003c\/b\u003e\u003c\/span\u003e, an element of great technical and collectible value.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cspan class=\"s1\"\u003eA top-tier offering, combining \u003c\/span\u003e\u003cb\u003ehistorical prestige, selected construction, and reference sound performance\u003c\/b\u003e\u003cspan class=\"s1\"\u003e.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eSound Characteristics\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eBass\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eDeep and controlled, with a solid and authoritative structure that brings balance to the soundstage.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMids\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eRich, refined, and three-dimensional. Vocals emerge with great naturalness and presence, with an extremely elegant harmonic texture.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eHighs\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eSweet and silky, with natural extension and always fluid, never fatiguing rendition.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eDynamics\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eLinear and controlled, with extremely stable and consistent response.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eSoundstage\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eWide, airy, and well-focused, with excellent separation and credible depth.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003e🎧 Use in Hi-Fi Amplifiers\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eIdeal for:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"p1\"\u003ehigh-end preamplifiers\u003c\/li\u003e\n\u003cli class=\"p1\"\u003einput stages\u003c\/li\u003e\n\u003cli class=\"p1\"\u003esystems where maximum stability and consistency are required\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003eThanks to the \u003cspan class=\"s2\"\u003e\u003cb\u003eSpecial Red\u003c\/b\u003e\u003c\/span\u003e selection, they offer extremely reliable behavior, with refined and controlled sound performance.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003e🎸 Use in Musical Applications\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003ePerfect for:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"p1\"\u003etube preamplifiers\u003c\/li\u003e\n\u003cli class=\"p1\"\u003equality instrument amplifiers\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003eThey offer:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"p1\"\u003ebalanced dynamic response\u003c\/li\u003e\n\u003cli class=\"p1\"\u003egreat definition\u003c\/li\u003e\n\u003cli class=\"p1\"\u003eelegant and musical sonic character\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003e🎯 Note for audiophiles and technicians\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eRCA USA – year 1952 (same date codes 3-52)\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003e5693 \/ CV3699 – Special Red\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eSelected Matched Pair NOS\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003ePerfectly matching values between the two units\u003c\/b\u003e\u003c\/li\u003e\n\u003cli class=\"p1\"\u003e\u003cb\u003eVTT Classification: VERY STRONG\u003c\/b\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"p1\"\u003eA pair that represents not only a technical choice but a true \u003cspan class=\"s1\"\u003e\u003cb\u003ecult object for enthusiasts and collectors\u003c\/b\u003e\u003c\/span\u003e, capable of offering a \u003cspan class=\"s1\"\u003e\u003cb\u003erefined sound experience and a unique aesthetic presence\u003c\/b\u003e\u003c\/span\u003e, in the full style of the great American tubes of the 1950s.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eTube tested on \u003cstrong\u003eAMPLITREX AT-1000 \u003c\/strong\u003eTube Tester:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest Conditions:\u003c\/strong\u003e\u003cspan\u003e \u003cmeta charset=\"utf-8\"\u003eVa = 250V; Vg2 = 100V; Vg = -3V \u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAverage 100%:\u003c\/strong\u003e\u003cspan\u003e \u003cmeta charset=\"utf-8\"\u003eGm = 1.6 ; Ia = 3.0 mA\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest Result:\u003c\/strong\u003e VERY STRONG\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cstrong\u003eTube 1:\u003c\/strong\u003e \u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eGm = 1.5 ; Ia = 2.7 mA\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cmeta charset=\"utf-8\"\u003e\u003cstrong\u003eTube 2:\u003c\/strong\u003e \u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003eGm = 1.5 ; Ia = 2.7 mA\u003c\/span\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\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\u003eLow. Tested and compliant for hi-fi use, including phono stages and guitar amplifiers.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eEmission Quality:\u003c\/strong\u003e Excellent – Very strong and stable emission, without fluctuations.\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eShorts 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 data-end=\"371\" data-start=\"221\"\u003e\n\u003cstrong data-end=\"233\" data-start=\"223\"\u003eCondition:\u003c\/strong\u003e NOS - New Old Stock - Tested and functional - Supplied in our custom box for optimal protection. \u003c\/li\u003e\n\u003cli data-end=\"456\" data-start=\"372\"\u003e\n\u003cstrong data-end=\"391\" data-start=\"374\"\u003eFunctionality:\u003c\/strong\u003e Perfectly operational, with excellent test results.\u003c\/li\u003e\n\u003cli data-end=\"672\" data-start=\"457\"\u003e\n\u003cstrong data-end=\"484\" data-start=\"459\"\u003eCosmetic Condition:\u003c\/strong\u003e Excellent – Markings excellently preserved, minimal signs of age. See photos for details.\u003c\/li\u003e\n\u003cli data-end=\"797\" data-start=\"673\"\u003e\n\u003cstrong data-end=\"703\" data-start=\"675\"\u003eManufacturing Code:\u003c\/strong\u003e 3-52 → RMA\/EIA Open Date Code → manufactured the 52nd week of 1953 → Radio Corporation of America, Camden, N. J.\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=\"Perché le nostre valvole sono diverse – il protocollo VTT che migliora suono, affidabilità e durata\" rel=\"noopener\" target=\"_blank\"\u003e\u003cstrong\u003eDiscover why our tubes are different →\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"RCA","offers":[{"title":"Default Title","offer_id":57347164307804,"sku":"03526L","price":3699.0,"currency_code":"CZK","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/2_7d674d7c-af9a-496f-aba9-d3e7e6798bac.jpg?v=1776097442","url":"https:\/\/vacuumtubestreasures.com\/en-cz\/products\/5693-cv3699-rca-nos-special-red-amplitrex-matched-pair-tubes-made-in-usa-52","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}