{"product_id":"mullard-cv4004-matched-pair","title":"Mullard CV4004 Matched Pair","description":"\u003ch2 data-section-id=\"12jiecl\" data-start=\"0\" data-end=\"38\"\u003eMullard CV4004 \/ 12AX7 NOS NIB Matched Pair\u003c\/h2\u003e\n\u003cp data-start=\"40\" data-end=\"161\"\u003eSome tubes are bought because they work. Others are bought because they are the one people have been chasing for decades.\u003c\/p\u003e\n\u003cp data-start=\"163\" data-end=\"208\"\u003eThe \u003cstrong data-start=\"167\" data-end=\"185\"\u003eMullard CV4004\u003c\/strong\u003e is one of those tubes.\u003c\/p\u003e\n\u003cp data-start=\"210\" data-end=\"644\"\u003eAlso known as the \u003cstrong data-start=\"228\" data-end=\"237\"\u003eM8137\u003c\/strong\u003e, the CV4004 is the ruggedized British military version of the \u003cstrong data-start=\"300\" data-end=\"317\"\u003e12AX7 \/ ECC83\u003c\/strong\u003e. It was built for serious use, with a stronger construction than a standard consumer-grade preamp tube. Original Mullard CV4004 tubes are especially known for their distinctive \u003cstrong data-start=\"495\" data-end=\"521\"\u003ebox plate construction\u003c\/strong\u003e, which makes them easy to spot and highly desirable among collectors and tube users. \u003cspan class=\"\" data-state=\"closed\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cdiv class=\"qMYqUG_convSearchResultHighlightRoot\"\u003e\n\u003cdiv class=\"\" data-turn-id-container=\"request-6a04d7d6-34b0-83e8-9c62-92c50c585c47-13\" data-is-intersecting=\"true\"\u003e\n\u003cdiv class=\"relative w-full overflow-visible\"\u003e\n\u003csection class=\"text-token-text-primary w-full focus:outline-none [--shadow-height:45px] has-data-writing-block:pointer-events-none has-data-writing-block:-mt-(--shadow-height) has-data-writing-block:pt-(--shadow-height) [\u0026amp;:has([data-writing-block])\u0026gt;*]:pointer-events-auto R6Vx5W_threadScrollVars scroll-mb-[calc(var(--scroll-root-safe-area-inset-bottom,0px)+var(--thread-response-height))] scroll-mt-[calc(var(--header-height)+min(200px,max(70px,20svh)))]\" dir=\"auto\" data-turn-id=\"request-6a04d7d6-34b0-83e8-9c62-92c50c585c47-13\" data-turn-id-container=\"request-6a04d7d6-34b0-83e8-9c62-92c50c585c47-13\" data-testid=\"conversation-turn-30\" data-scroll-anchor=\"false\" data-turn=\"assistant\"\u003e\n\u003cdiv class=\"text-base my-auto mx-auto pb-10 [--thread-content-margin:var(--thread-content-margin-xs,calc(var(--spacing)*4))] @w-sm\/main:[--thread-content-margin:var(--thread-content-margin-sm,calc(var(--spacing)*6))] @w-lg\/main:[--thread-content-margin:var(--thread-content-margin-lg,calc(var(--spacing)*16))] px-(--thread-content-margin)\"\u003e\n\u003cdiv class=\"[--thread-content-max-width:40rem] @w-lg\/main:[--thread-content-max-width:48rem] mx-auto max-w-(--thread-content-max-width) flex-1 group\/turn-messages focus-visible:outline-hidden relative flex w-full min-w-0 flex-col agent-turn\"\u003e\n\u003cdiv class=\"flex max-w-full flex-col gap-4 grow\"\u003e\n\u003cdiv data-message-author-role=\"assistant\" data-message-id=\"254e49e6-1e71-4a57-b07f-5ccbf32d61ed\" dir=\"auto\" data-message-model-slug=\"gpt-5-5-thinking\" class=\"min-h-8 text-message relative flex w-full flex-col items-end gap-2 text-start break-words whitespace-normal outline-none keyboard-focused:focus-ring [.text-message+\u0026amp;]:mt-1\" data-turn-start-message=\"true\" tabindex=\"0\"\u003e\n\u003cdiv class=\"flex w-full flex-col gap-1 empty:hidden\"\u003e\n\u003cdiv class=\"markdown prose dark:prose-invert wrap-break-word w-full dark markdown-new-styling\"\u003e\n\u003cp data-start=\"646\" data-end=\"909\"\u003eThis listing is for a \u003cstrong data-start=\"668\" data-end=\"684\"\u003ematched pair\u003c\/strong\u003e, making it a great choice for hi-fi preamps, phono stages, stereo gear, and guitar amps where balanced performance matters. The CV4004 has the same basic tube family as a 12AX7 \/ ECC83, but with a more premium, rugged build.\u003c\/p\u003e\n\u003cp data-start=\"911\" data-end=\"1208\"\u003eIn audio gear, Mullard preamp tubes are loved for their rich midrange, smooth top end, and natural warmth. The CV4004 version gives you that classic Mullard character with a more controlled, stable presentation. It is a great option when you want vintage tone without a noisy or overly loose tube.\u003c\/p\u003e\n\u003ch3 data-section-id=\"3zmk2l\" data-start=\"1210\" data-end=\"1222\"\u003eBest For\u003c\/h3\u003e\n\u003cul data-start=\"1224\" data-end=\"1393\"\u003e\n\u003cli data-section-id=\"1suyazn\" data-start=\"1224\" data-end=\"1241\"\u003eHi-fi preamps\u003c\/li\u003e\n\u003cli data-section-id=\"1b2pvvt\" data-start=\"1242\" data-end=\"1258\"\u003ePhono stages\u003c\/li\u003e\n\u003cli data-section-id=\"261ojp\" data-start=\"1259\" data-end=\"1282\"\u003eVintage stereo gear\u003c\/li\u003e\n\u003cli data-section-id=\"1dvrl21\" data-start=\"1283\" data-end=\"1314\"\u003eGuitar amp preamp positions\u003c\/li\u003e\n\u003cli data-section-id=\"18uutwh\" data-start=\"1315\" data-end=\"1337\"\u003ePhase inverter use\u003c\/li\u003e\n\u003cli data-section-id=\"1ks8d05\" data-start=\"1338\" data-end=\"1393\"\u003eReplacing 12AX7 \/ ECC83 \/ CV4004 \/ M8137 tube types\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1395\" data-end=\"1467\"\u003eEach pair is tested and matched for proper operation, balance, and life.\u003c\/p\u003e\n\u003cp data-start=\"1469\" data-end=\"1590\"\u003e\u003cstrong data-start=\"1469\" data-end=\"1590\"\u003eA rare matched pair of Mullard CV4004 box plate tubes — the rugged British 12AX7 made for serious vintage audio gear.\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Fuzz Audio","offers":[{"title":"Default Title","offer_id":42395981578275,"sku":null,"price":632.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0275\/0699\/9331\/files\/Mullard_CV4004_12AX7_NOS_NIB_Matched_Pair.jpg?v=1778792889","url":"https:\/\/fuzzaudio.shop\/en-ca\/products\/mullard-cv4004-matched-pair","provider":"Fuzz Audio","version":"1.0","type":"link"}