{"product_id":"stc-cv391-5b-255m-vacuum-tube","title":"STC CV391 (5B\/255M) Vacuum Tube","description":"\u003cdiv data-is-intersecting=\"true\" data-turn-id-container=\"request-WEB:aa5978b9-3b86-4678-a02b-8fc60ab44037-2\" class=\"\"\u003e\n\u003csection data-turn=\"assistant\" data-testid=\"conversation-turn-2\" data-turn-id-container=\"request-WEB:aa5978b9-3b86-4678-a02b-8fc60ab44037-2\" data-turn-id=\"request-WEB:aa5978b9-3b86-4678-a02b-8fc60ab44037-2\" dir=\"auto\" class=\"text-token-text-primary w-full focus:outline-none has-data-writing-block:pointer-events-none [\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)))]\"\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\" data-conversation-screenshot-content=\"\"\u003e\n\u003cdiv class=\"flex max-w-full flex-col gap-4 grow\"\u003e\n\u003cdiv data-turn-start-message=\"true\" 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-message-model-slug=\"gpt-5-5\" dir=\"auto\" data-message-id=\"61d862b8-5844-4808-baff-ca3d2fe632ea\" data-message-author-role=\"assistant\" 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 light markdown-new-styling\"\u003e\n\u003cdiv class=\"qMYqUG_convSearchResultHighlightRoot qMYqUG_convSearchResultTextHighlightSafari\"\u003e\n\u003cdiv data-is-intersecting=\"true\" data-turn-id-container=\"request-WEB:c0812bd4-af2f-4283-93ae-e21330d72c29-4\" class=\"\"\u003e\n\u003csection data-turn=\"assistant\" data-testid=\"conversation-turn-2\" data-turn-id-container=\"request-WEB:c0812bd4-af2f-4283-93ae-e21330d72c29-4\" data-turn-id=\"request-WEB:c0812bd4-af2f-4283-93ae-e21330d72c29-4\" dir=\"auto\" class=\"text-token-text-primary w-full focus:outline-none has-data-writing-block:pointer-events-none [\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)))]\"\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\" data-conversation-screenshot-content=\"\"\u003e\n\u003cdiv class=\"flex max-w-full flex-col gap-4 grow\"\u003e\n\u003cdiv data-turn-start-message=\"true\" 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-message-model-slug=\"gpt-5-5\" dir=\"auto\" data-message-id=\"239085b0-31b4-40cd-80cb-d2eec9bb8d8b\" data-message-author-role=\"assistant\" 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 light markdown-new-styling\"\u003e\n\u003cdiv class=\"qMYqUG_convSearchResultHighlightRoot qMYqUG_convSearchResultTextHighlightSafari\"\u003e\n\u003cdiv class=\"\" data-turn-id-container=\"request-WEB:78739712-89cd-4b2e-9e9f-03395acb850e-6\" data-is-intersecting=\"true\"\u003e\n\u003csection class=\"text-token-text-primary w-full focus:outline-none has-data-writing-block:pointer-events-none [\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-WEB:78739712-89cd-4b2e-9e9f-03395acb850e-6\" data-turn-id-container=\"request-WEB:78739712-89cd-4b2e-9e9f-03395acb850e-6\" data-testid=\"conversation-turn-2\" 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 data-conversation-screenshot-content=\"\" 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=\"0d9a18a5-4374-49f6-b7ca-08e42f5593f9\" dir=\"auto\" data-message-model-slug=\"gpt-5-5\" 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 light markdown-new-styling\"\u003e\n\u003cp data-start=\"0\" data-end=\"1000\" data-is-last-node=\"\" data-is-only-node=\"\"\u003e\u003cspan\u003eThis CV391 (5B\/255M) was manufactured in England by Standard Telephones and Cables (STC) as a transmitting and power-amplifier vacuum tube for British government and industrial applications. Electrically similar to the 807 and 6L6 families, it boasts the rugged construction standards associated with British military and communications equipment. \u003c\/span\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\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\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\u003ch2\u003e\u003cstrong\u003eArchive Assessed, Apos Assured\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eAll Archive tubes are thoroughly tested, inspected, photographed, and inventoried, guaranteeing the quality of each tube that's shipped to customers. All tubes carry an Apos 12-month warranty against manufacturing defects.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eAre the tubes...dusty...?\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eBecause these are genuine New Old Stock tubes, small cosmetic irregularities may be present. These aren't defects but artifacts of vintage manufacturing and decades of storage. They have no impact on reliability or sonic performance.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eSpecs\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand \/ Type:\u003c\/strong\u003e STC CV391 (5B\/255M)\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eMilitary Grade: \u003c\/b\u003eYes\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMade in:\u003c\/strong\u003e UK\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBox Type:\u003c\/strong\u003e NOS in New Box\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTested on:\u003c\/strong\u003e Amplitrex AT1000 Advanced Digital Tube Tester\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Archive Tubes","offers":[{"title":"Matched Pair (2 Tubes) \/ Archive Vault","offer_id":47977753542892,"sku":"APS-1388-1","price":188.0,"currency_code":"USD","in_stock":true},{"title":"Matched Pair (2 Tubes) \/ Gold","offer_id":47977753575660,"sku":"APS-1388-2","price":171.0,"currency_code":"USD","in_stock":true},{"title":"Matched Pair (2 Tubes) \/ Silver","offer_id":47977753608428,"sku":"APS-1388-3","price":160.0,"currency_code":"USD","in_stock":true},{"title":"Matched Quad (4 Tubes) \/ Archive Vault","offer_id":47977753641196,"sku":"APS-1388-4","price":376.0,"currency_code":"USD","in_stock":true},{"title":"Matched Quad (4 Tubes) \/ Gold","offer_id":47977753673964,"sku":"APS-1388-5","price":342.0,"currency_code":"USD","in_stock":true},{"title":"Matched Quad (4 Tubes) \/ Silver","offer_id":47977753706732,"sku":"APS-1388-6","price":320.0,"currency_code":"USD","in_stock":true},{"title":"Singles  (1 Tube) \/ Archive Vault","offer_id":47977753739500,"sku":"APS-1388-7","price":84.0,"currency_code":"USD","in_stock":true},{"title":"Singles  (1 Tube) \/ Gold","offer_id":47977753772268,"sku":"APS-1388-8","price":75.0,"currency_code":"USD","in_stock":true},{"title":"Singles  (1 Tube) \/ Silver","offer_id":47977753805036,"sku":"APS-1388-9","price":70.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0225\/2721\/3642\/files\/STCCV391_4.jpg?v=1784734829","url":"https:\/\/apos.audio\/products\/stc-cv391-5b-255m-vacuum-tube","provider":"Apos","version":"1.0","type":"link"}