{"product_id":"5751-rca-nos-black-plates-halo-getter-matched-pair-tubes-made-in-usa","title":"5751 RCA NOS Black Plates Halo Getter Matched Pair Tubes Made in USA","description":"\u003ch3\u003e\u003cstrong\u003e5751 RCA NOS Black Plates Halo Getter Tubes Made in USA\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eAMPLITREX Tested \u003cmeta charset=\"utf-8\"\u003e– Ultra Low Noise \u0026amp; Microphonics –\u003cspan\u003e VERY STRONG - Vintage American RCA Production\u003c\/span\u003e\u003c\/strong\u003e\u003c\/p\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\n\u003cli\u003e\n\n\u003cstrong\u003eTest Conditions:\u003c\/strong\u003e\u003cspan\u003e Va = 250V ; Vg = -3V\u003c\/span\u003e\n\n\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003e100% Average:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = 1200 ; Ia = 1.0 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eTest Result:\u003c\/strong\u003e VERY STRONG\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eTube 1:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 1:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = 1400 ; Ia = 1.2 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 2:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = 1300 ; Ia = 1.1 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eTube 2:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 1:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = 1300 ; Ia = 1.3 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 2:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = 1500 ; Ia = 1.6 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cdiv\u003e\n\n\u003cmeta charset=\"utf-8\"\u003e\n\n\u003cdiv\u003e\u003cstrong\u003eAdditional Tests Performed:\u003c\/strong\u003e\u003c\/div\u003e\n\n\u003cul\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eBurn-in \/ Stability Test: \u003c\/strong\u003e48h – OK\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eMicrophonics:\u003c\/strong\u003e Very Low. Tested and confirmed for use in hi-fi equipment and guitar amplifiers, even in the most sensitive audio stages.\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eNoise: \u003c\/strong\u003eLow and well-controlled. Quiet operation in hi-fi environments and in musical amplifiers in the intended positions.\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eBalance:\u003c\/strong\u003e Good. The sections show a consistent balance, fully compatible with use in hi-fi environments and musical amplifiers, in all applications where absolute symmetry between sections is not required.\u003c\/span\u003e\u003c\/li\u003e\n\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\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eShort Circuits and GAS:\u003c\/strong\u003e Absent.\u003c\/span\u003e\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\n\n\u003c\/div\u003e\n\u003ch3\u003e\u003cstrong\u003eDescription:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-pm-slice=\"1 1 []\"\u003e\u003cspan\u003eImportant pair of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e5751 RCA NOS of American production\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, characterized by the sought-after \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eBlack Plates\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and the classic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eHalo Getter\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. The internal structure of the two pieces is consistent, while the silkscreens show a different degree of preservation: one tube retains part of the original orange marking, while on the other the lettering has almost completely disappeared. The construction characteristics allow them to be indicatively attributed to production in the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1960s\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe tests performed with the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eAmplitrex AT-1000\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e highlight performance clearly superior to the nominal reference of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1200 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. The four sections indeed measure between \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1300 and 1500 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with anode currents between \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1.1 and 1.6 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. The transconductance averages of the two tubes are particularly close: \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1350 and 1400 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with a variance of less than \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e4%\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, confirming excellent overall electrical consistency.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe internal balance is also good: Tube 1 measures \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1400\/1300 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1.2\/1.1 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, while Tube 2 reaches \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1300\/1500 µmhos\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1.3\/1.6 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. This is not a selection with absolute symmetry between all sections, but rather two strong, stable units fully suitable for normal audio applications compatible with the 5751.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e48-hour burn-in\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e verified the stability of the parameters, with no fluctuations, short circuits, or gas presence. Particularly significant is the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eUltra Low Noise \u0026amp; Microphonics\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e selection: both tubes showed very contained noise and extremely low microphonics, qualities that are fundamental in the most delicate audio positions.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThese characteristics make them particularly suitable for hi-fi preamplifiers, compatible phono stages, headphone amplifiers, and guitar amplifiers, even in \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eV1\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e and high-sensitivity input stages. The 5751 offers a lower amplification factor than the 12AX7 and can be an interesting choice when more control, more headroom, and a less aggressive response are desired; compatibility must, however, be verified in relation to the circuit used.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eIn terms of sound, RCA Black Plates are appreciated for a \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003efull-bodied, musical, and natural\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e reproduction, with a rich and well-articulated midrange, solid low frequencies, and a high end that is defined without being harsh. In hi-fi systems, they promote depth, tonal coherence, and fatigue-free listening; in guitar amplifiers, they offer dynamic response, control, and excellent articulation, preserving the instrument's character.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eA high-level offering for those looking for two \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e5751 RCA NOS Made in USA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e tubes, with Black Plates, Halo Getter, emission above reference, and a particularly rigorous selection for noise and microphonics: two authentic vintage tubes, tested individually and ready for use even in the most sensitive audio stages.\u003c\/span\u003e\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3\u003e\u003cstrong\u003eCondition:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eCondition:\u003c\/strong\u003e NOS - New Old Stock - Tested and functional - Supplied in our custom box for optimal protection. \u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\n\n\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eFunctionality: \u003c\/strong\u003ePerfectly operational.\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\n\n\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eCosmetic condition:\u003c\/strong\u003e Adequate – One tube with lettering partially faded or poorly legible, one tube with lettering completely absent. General appearance shows obvious signs of age. See photos for details.\u003cstrong\u003e\u003cbr\u003e\u003c\/strong\u003e\n\n\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eManufacturing Code:\u003c\/strong\u003e RCA Radio Corporation of America production, Camden, N. J. - Code undecipherable. Production indicatively attributable to the 1960s based on construction features.\u003c\/li\u003e\n\n\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":59351921164636,"sku":"03866L","price":67700.0,"currency_code":"HUF","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/2_b24d8432-a93d-463a-a64c-c590f9be841f.jpg?v=1791131562","url":"https:\/\/vacuumtubestreasures.com\/en-hu\/products\/5751-rca-nos-black-plates-halo-getter-matched-pair-tubes-made-in-usa","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}