{"product_id":"71a-sylvania-nos-matched-pair-silver-plates-foil-dimpled-getter-usa-40s-same-data-codes-4v-amplitrex-tested-very-strong","title":"71A SYLVANIA NOS Matched Pair Silver Plates Hanging Filaments Foil Getter USA – Same Data Codes 4V – VERY STRONG","description":"\u003cp class=\"p1\"\u003e\u003cb\u003e71A SYLVANIA NOS Matched Pair Silver Plates Hanging Filaments Foil Dimpled Getter Made in USA – Same Data Codes 4V\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cspan class=\"s1\"\u003e\u003cb\u003eAMPLITREX Tested – VERY STRONG – Low Noise \u0026amp; Microphonics\u003c\/b\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eGeneral Description\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eThis pair of \u003cspan class=\"s1\"\u003e\u003cb\u003e71A Sylvania NOS – Made in USA\u003c\/b\u003e\u003c\/span\u003e represents a selection of great historical and collector's appeal, dedicated to vintage amplification enthusiasts, period restorations, and low-power single-ended projects.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe \u003cspan class=\"s1\"\u003e\u003cb\u003e71A\u003c\/b\u003e\u003c\/span\u003e is a small \u003cspan class=\"s1\"\u003e\u003cb\u003eDHT – Directly Heated Triode\u003c\/b\u003e\u003c\/span\u003e, a direct-heated tube belonging to the great American tradition of early audio amplifications. It is a type that is increasingly sought after today for its immediate, natural, and intimately musical sonic character, particularly appreciated in simple and refined circuits, where the quality of the tube plays a central role in the final output.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThis pair features a construction of remarkable elegance and strong historical appeal: \u003cspan class=\"s1\"\u003e\u003cb\u003eST glass\u003c\/b\u003e\u003c\/span\u003e, \u003cspan class=\"s1\"\u003e\u003cb\u003esilver plates\u003c\/b\u003e\u003c\/span\u003e, \u003cspan class=\"s1\"\u003e\u003cb\u003efoil dimpled getter\u003c\/b\u003e\u003c\/span\u003e, \u003cspan class=\"s1\"\u003e\u003cb\u003ehanging filaments\u003c\/b\u003e\u003c\/span\u003e, and \u003cspan class=\"s1\"\u003e\u003cb\u003eblack 4-pin base\u003c\/b\u003e\u003c\/span\u003e. The hanging filament structure is a particularly interesting detail in small direct-heated triodes, as it recalls a carefully crafted and visually very scenic period construction. Both tubes bear the same \u003cspan class=\"s1\"\u003e\u003cb\u003e4V\u003c\/b\u003e\u003c\/span\u003e code, a detail that reinforces the consistency of the selection. Production is likely attributable to the 1940s, cautiously indicated as \u003cspan class=\"s1\"\u003e\u003cb\u003elikely 1940s production\u003c\/b\u003e\u003c\/span\u003e.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe aesthetic conditions are \u003cspan class=\"s1\"\u003e\u003cb\u003eexcellent, museum-quality\u003c\/b\u003e\u003c\/span\u003e, with a very well-maintained general presentation. The only aesthetic note concerns the \u003cspan class=\"s1\"\u003e\u003cb\u003e71A\u003c\/b\u003e\u003c\/span\u003e branding on the glass of one of the two tubes, which is less visible\/partially faded. The tubes are not supplied with original boxes.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eSonic Characteristics\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eThe 71A Sylvania offers a sonic signature typical of small direct-heated triodes: intimate, fluid, natural, and rich in micro-information. It is not a tube designed for high power, but for those seeking tonal refinement, expressive immediacy, and a listening experience with a strong vintage flavor.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eBass\u003c\/b\u003e\u003cbr\u003eThe bass is dry, controlled, and well-articulated, more oriented towards precision and naturalness than impact force. In well-designed single-ended circuits, they contribute to a clean and coherent sound foundation.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eMids\u003c\/b\u003e\u003cbr\u003eThe mid-range is the heart of the 71A: open, direct, and very communicative. Vocals, acoustic instruments, and small ensembles are reproduced with great naturalness, with a refined harmonic texture and a very pleasant presence.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eHighs\u003c\/b\u003e\u003cbr\u003eThe highs are delicate, airy, and well-integrated. The high range maintains brightness and detail without becoming aggressive, contributing to an elegant and non-fatiguing reproduction.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eDynamics\u003c\/b\u003e\u003cbr\u003eDynamics are fast and sensitive to small musical variations. The 71A excels in microdynamics, transient response, and the ability to reproduce subtle nuances with great naturalness.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003eSoundstage\u003c\/b\u003e\u003cbr\u003eThe soundstage is focused, precise, and very credible. In high-efficiency systems, it can offer a refined three-dimensional image, with good separation between instruments and a remarkable sense of presence.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003e🎧 Use in Hi-Fi Amplifiers\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eThis pair is particularly interesting for vintage amplifications, philological restorations, and \u003cspan class=\"s1\"\u003e\u003cb\u003elow-power single-ended\u003c\/b\u003e\u003c\/span\u003e projects based on DHT tubes. The 71A is an ideal choice for those seeking an essential, transparent, and strongly linked to the tradition of early audio amplifications.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eThe selection as a \u003cspan class=\"s1\"\u003e\u003cb\u003eMatched Pair\u003c\/b\u003e\u003c\/span\u003e, combined with the \u003cspan class=\"s1\"\u003e\u003cb\u003eVERY STRONG\u003c\/b\u003e\u003c\/span\u003e result and the \u003cspan class=\"s1\"\u003e\u003cb\u003eLow Noise \u0026amp; Microphonics\u003c\/b\u003e\u003c\/span\u003e behavior, makes this pair suitable for quality applications in compatible circuits, where electrical coherence and quietness are important elements.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003e🎸 Use in Musical Applications\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eIn compatible musical and experimental applications, the 71A can offer a very personal character: fluid response, natural compression, and a particularly fascinating vintage harmonic texture. It is a tube indicated for those seeking an authentic, unconventional sonic voice strongly linked to the history of tube amplification.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003e🎯 Note for Audiophiles and Technicians\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp class=\"p1\"\u003eThe Sylvania datasheet indicates, at the typical point with \u003cspan class=\"s1\"\u003e\u003cb\u003eVa = 135V\u003c\/b\u003e\u003c\/span\u003e, approximately \u003cspan class=\"s1\"\u003e\u003cb\u003eIa = 17.3 mA\u003c\/b\u003e\u003c\/span\u003e and \u003cspan class=\"s1\"\u003e\u003cb\u003eMutual Conductance = 1650 µmhos\u003c\/b\u003e\u003c\/span\u003e, equivalent to about \u003cspan class=\"s1\"\u003e\u003cb\u003e1.65 mA\/V\u003c\/b\u003e\u003c\/span\u003e. The values measured on Amplitrex are therefore fully consistent with the original Sylvania operating data, confirming the excellent electrical condition of the pair.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eA high-level, rare, and fascinating pair of 71A Sylvania NOS, designed for those who desire a true vintage American selection: not just simple vintage tubes, but a historical, coherent, strong DHT pair ready for refined applications in the full style of Vacuum Tubes Treasures.\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 = 135V ; Vg = -27V \u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli style=\"font-weight: bold;\"\u003e\u003cstrong\u003eMeasurements taken after 3 minutes warm-up.\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e100% Average:\u003c\/strong\u003e\u003cspan\u003e \u003cmeta charset=\"utf-8\"\u003eGm = 1.5 ; Ia = 17.5 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 = 1.6 ; Ia = 14.6 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 = 1.7 ; Ia = 18.2 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 suitable for hi-fi use, including in 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\u003eCondition:\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 working - 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 very well preserved, minimal signs of age. \u003cmeta charset=\"utf-8\"\u003eThe only aesthetic note concerns the \u003cspan class=\"s1\"\u003e\u003cb\u003e71A\u003c\/b\u003e\u003c\/span\u003e branding on the glass of one of the two tubes, which is less visible\/partially faded. See photos for details.\u003c\/li\u003e\n\u003cli data-end=\"672\" data-start=\"457\"\u003e\n\u003cstrong\u003eManufacturing code:\u003c\/strong\u003e 4V - Made in the USA - The construction suggests probable 1940s \/ early post-war production, with ST glass structure, black 4-pin base, silver plates, foil dimpled getter, and hanging filaments, characteristics consistent with Sylvania's American productions of that era. Both tubes bear the same \"4V\" code, an element that reinforces the historical, aesthetic, and constructive coherence of the pair.\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":"SYLVANIA","offers":[{"title":"Default Title","offer_id":57497867714908,"sku":"03560Z","price":199.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/3_bb72d08f-0fdb-4932-b231-59838289c669.jpg?v=1777539327","url":"https:\/\/vacuumtubestreasures.com\/en\/products\/71a-sylvania-nos-matched-pair-silver-plates-foil-dimpled-getter-usa-40s-same-data-codes-4v-amplitrex-tested-very-strong","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}