{"product_id":"7025-12ax7-ecc83-webcor-by-mullard-blackburn-short-gray-plates-halo-getter-tube-uk","title":"7025 \/ 12AX7 \/ ECC83 Webcor by Mullard Blackburn 1962 - Short Gray Plates - Halo Getter - Balanced Section","description":"\u003ch3\u003e\n\n\u003cmeta charset=\"utf-8\"\u003e \u003cstrong\u003e7025 \/ 12AX7 \/ ECC83 Webcor by MULLARD – Blackburn (Great Britain) 1962\u003c\/strong\u003e\u003cbr\u003e\u003cstrong\u003eShort Gray Plates – Halo Getter – Balanced Section – Low Noise \u0026amp; Microphonics\u003c\/strong\u003e\u003cbr\u003e\n\n\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eAMPLITREX Tested – STRONG – Low Noise \u0026amp; Microphonics \u003cmeta charset=\"utf-8\"\u003e– Vintage GT. BRITAIN \u003cmeta charset=\"utf-8\"\u003eMULLARD Production\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eTest Results:\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eTube tested on\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eAMPLITREX AT-1000\u003cspan\u003e \u003c\/span\u003e\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 = -2V\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 = 1600 ; Ia = 1.2 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eTest Result:\u003c\/strong\u003e STRONG\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eTube :\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 = 1500 ; Ia = 0.8 mA\u003c\/li\u003e\n\n\u003cli\u003e\n\n\u003cstrong\u003eSection 2:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eGm = \u003cmeta charset=\"utf-8\"\u003e1500 ; Ia = \u003cmeta charset=\"utf-8\"\u003e0.8 mA\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cdiv\u003e\u003cstrong\u003eAdditional Tests Performed:\u003c\/strong\u003e\u003c\/div\u003e\n\u003cul\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eBurn-in \/ Stability Test:\u003c\/strong\u003e 48h – OK\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eMicrophonics:\u003c\/strong\u003e Very Low. Tested and suitable for use in hi-fi equipment and guitar amplifiers, including the most sensitive audio stages.\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eBalance:\u003c\/strong\u003e Excellent - The sections are consistent and well-aligned, making the tube suitable for use as a phase inverter in hi-fi and instrument applications.\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eEmission Quality:\u003c\/strong\u003e Strong – Strong and even emission, suitable for any application.\u003c\/span\u003e\u003c\/li\u003e\n\n\u003cli\u003e\u003cspan\u003e\u003cstrong\u003eShort Circuits and GAS:\u003c\/strong\u003e None.\u003c\/span\u003e\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eDescription\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp data-pm-slice=\"1 1 []\"\u003e\u003cspan\u003eSelected vintage specimen of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e7025 \/ 12AX7 \/ ECC83 Webcor by Mullard\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, produced at the historic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eMullard factory in Blackburn, Great Britain, in December 1962\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e. Originally marketed under the American Webcor brand, this tube retains the authentic British construction of \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eShort Gray Plates with Halo Getter\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, a feature of Mullard production from this period. The original code \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eI61 B2L5\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e documents its production identity and date, making it particularly interesting for audiophiles and collectors looking for authentic vintage Mullard tubes.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe measurements performed with the \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eAmplitrex AT-1000\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e highlight an \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eexcellent electrical balance\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with perfectly identical values in the two sections. The transconductance reaches \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e1500 µmhos for both triodes\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, corresponding to 93.75% of the nominal reference of 1600, while the anode currents are uniform at \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e0.8 mA\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, compared to the reference of 1.2 mA. Although the anode current is lower than the nominal value, the perfect correspondence of the measurements confirms a remarkable internal symmetry, particularly appreciated in applications requiring electrically balanced sections.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe tube has passed \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003e48 hours of burn-in and stability testing\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, maintaining a strong and even emission, without fluctuations, short circuits, or the presence of gas. The tests also confirmed \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003every low noise and microphonics levels\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, making this specimen particularly suitable even for the most sensitive audio stages, where silence and stability are of particular importance.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eMullard ECC83 Blackburn\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e tubes are traditionally appreciated in hi-fi preamplifiers, compatible phono stages, and guitar amplifiers, even in the V1 position and in phase inverter circuits. The British Mullard production of the 1960s is sought after by audiophiles for a musical presentation generally described as \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003ewarm, full-bodied, and refined\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, with a midrange rich in nuances, tonal naturalness, and pleasant expressive fluidity.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe value of this specimen lies in its \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eauthentic 1962 Mullard Blackburn production\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, its original \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eShort Gray Plates\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e construction, the perfect balance of the sections, and its selection for very low microphonics. The well-preserved silkscreening, very good cosmetic condition, and legible manufacturing code complete a vintage tube of particular interest. An authentic \u003c\/span\u003e\u003cstrong\u003e\u003cspan\u003eWebcor by Mullard Blackburn\u003c\/span\u003e\u003c\/strong\u003e\u003cspan\u003e, carefully tested and selected, for those who wish to rediscover the charm of historic British thermionic production through a specimen with documented electrical characteristics.\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\u003cspan\u003e Vintage Tubes - Tested and perfectly functional. Supplied in our custom box for optimal protection. \u003c\/span\u003e\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\u003cspan\u003e Very Good – Markings clearly legible with slight signs of age. See photos for details.\u003c\/span\u003e\n\n\u003c\/li\u003e\n\n\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eManufacturing Code:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\n\u003cli\u003e\n\n\u003cmeta charset=\"utf-8\"\u003e \u003cspan\u003eI61 B2L5→ I6x indicates an ECC83 with the sequential progression of x, where the increment of x indicates production changes - \u003cmeta charset=\"utf-8\"\u003eB2L5\u003c\/span\u003e\u003cspan\u003e B → Mullard, Blackburn - 2 (out of four digits ) → 1962 - L → December - 5 \u003cmeta charset=\"utf-8\"\u003e→ fifth week of the month\u003c\/span\u003e\n\n\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=\"Why our tubes are different – the VTT protocol that improves sound, reliability, and longevity\" rel=\"noopener\" target=\"_blank\"\u003e\u003cstrong\u003eDiscover why our tubes are different →\u003c\/strong\u003e\u003c\/a\u003e\u003c\/p\u003e","brand":"MULLARD","offers":[{"title":"Default Title","offer_id":59787687461212,"sku":"03920","price":199.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0616\/3775\/5127\/files\/2_51ca6d0f-64a2-43cd-879c-6a425523cd88.jpg?v=1793989129","url":"https:\/\/vacuumtubestreasures.com\/en-au\/products\/7025-12ax7-ecc83-webcor-by-mullard-blackburn-short-gray-plates-halo-getter-tube-uk","provider":"Vacuum Tubes Treasures","version":"1.0","type":"link"}