{"product_id":"fosi-audio-im4","title":"Fosi Audio IM4 10mm Dual-Cavity Dynamic Driver Open-Back In-Ear Monitor Earphone","description":"\u003cstyle\u003e  body {font-family: Arial, sans-serif; background:#f9fafc; color:#222; margin:20px;}  .container {max-width:940px; margin:auto; background:#fff; border-radius:12px; box-shadow:0 6px 18px rgba(0,0,0,.08); padding:28px;}  h2 {font-size:22px; margin:18px 0 10px; color:#0b4a82;}  h3 {font-size:18px; margin:16px 0 8px; color:#0b4a82;}  p {line-height:1.75; margin:8px 0;}  ul {margin:10px 0 16px 20px;}  li {margin:6px 0;}  .badges span {display:inline-block; background:#eef6ff; border:1px solid #d4e6ff; color:#0b4a82; padding:6px 11px; border-radius:999px; margin:5px 6px 0 0; font-size:13px;}  .specs {width:100%; border-collapse:collapse; margin-top:12px;}  .specs th, .specs td {border:1px solid #e6e6e6; padding:10px 12px; text-align:left; vertical-align:top;}  .specs th {background:#fafafa; width:280px;}  .note {font-size:13px; color:#666; margin-top:10px;}  .product-images {margin:20px 0;}  .product-images img {max-width:100%; height:auto; display:block; margin:10px 0;}\u003c\/style\u003e\n\u003cdiv class=\"container\"\u003e\n\u003ch2\u003eFosi Audio IM4 Open-Back In-Ear Monitor with Dual-Cavity Design\u003c\/h2\u003e\n\u003cp\u003e\u003cem\u003eRevolutionary open-back design meets dual-cavity acoustic engineering—experience natural, spacious sound with exceptional comfort.\u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003eThe \u003cstrong\u003eFosi Audio IM4\u003c\/strong\u003e represents a breakthrough in open-back IEM design, featuring an innovative 10mm dual-cavity dynamic driver that delivers the expansive soundstage and natural tonality of open-back headphones in a compact, portable form factor. Unlike traditional closed IEMs, the IM4's open-back architecture eliminates acoustic pressure buildup, providing a more natural listening experience with reduced fatigue during extended sessions. With premium OFC silver-plated cable, ergonomic metal construction, and Fosi Audio's meticulous tuning expertise, the IM4 offers audiophile-grade performance for those who appreciate the unique characteristics of open-back sound.\u003c\/p\u003e\n\u003cdiv class=\"badges\"\u003e\n\u003cspan\u003e10mm Dynamic Driver\u003c\/span\u003e \u003cspan\u003eOpen-Back Design\u003c\/span\u003e \u003cspan\u003eDual-Cavity Structure\u003c\/span\u003e \u003cspan\u003eOFC Silver-Plated Cable\u003c\/span\u003e \u003cspan\u003eMetal Construction\u003c\/span\u003e \u003cspan\u003e3.5mm Connector\u003c\/span\u003e \u003cspan\u003eHi-Res Audio\u003c\/span\u003e\n\u003c\/div\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRevolutionary Open-Back Design:\u003c\/strong\u003e Unlike conventional closed IEMs, the IM4's open-back architecture allows air to flow freely, creating a more natural, speaker-like soundstage with exceptional width and depth. Experience music the way it was meant to be heard—open, airy, and fatigue-free.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDual-Cavity Acoustic Structure:\u003c\/strong\u003e Innovative dual-cavity design separates and optimizes bass and mid-high frequency reproduction. The front cavity handles mids and highs with precision, while the rear cavity delivers controlled, textured bass without muddiness.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e10mm High-Performance Dynamic Driver:\u003c\/strong\u003e Precision-engineered driver delivers exceptional detail retrieval, natural timbre, and accurate frequency response across the entire audio spectrum. The large diaphragm ensures powerful bass extension and smooth treble.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePremium OFC Silver-Plated Cable:\u003c\/strong\u003e High-purity oxygen-free copper cable with silver plating provides excellent conductivity and minimal signal loss. The 3.5mm connector ensures universal compatibility with smartphones, DAPs, and desktop amplifiers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eErgonomic Metal Construction:\u003c\/strong\u003e Durable metal housing provides excellent acoustic damping and resonance control while maintaining a lightweight, comfortable fit for extended listening sessions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNatural Sound Signature:\u003c\/strong\u003e Fosi Audio's reference tuning emphasizes natural tonality, excellent instrument separation, and a spacious soundstage—perfect for critical listening and enjoying all music genres authentically.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComfortable Fit:\u003c\/strong\u003e Lightweight design and ergonomic nozzle angle ensure secure, fatigue-free wearing comfort for hours of listening pleasure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVersatile Application:\u003c\/strong\u003e Perfect for home listening, studio monitoring, and enjoying music in quiet environments where the open-back design's advantages shine.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv class=\"product-images\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/Ad0ab6dd45d4945c89a4dbf64c1b3302dy.webp?v=1768917032\" alt=\"Fosi Audio IM4 Overview\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/Sac7fab8d332140a69abef7e9ce3e242bd.webp?v=1768917032\" alt=\"Fosi Audio IM4 Design\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/S9079a9befc5346ad85d774986aef12665.webp?v=1768917032\" alt=\"Fosi Audio IM4 Dual-Cavity Structure\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/S5eecb0c132ef4f2087133fe3c7caa9f1A.webp?v=1768917032\" alt=\"Fosi Audio IM4 Open-Back Technology\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/Se9cf5cf40d5047fb94823e8745361cb0K.webp?v=1768917032\" alt=\"Fosi Audio IM4 Cable\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/S740dcf09a9b74c51b7faa7357996f5710.webp?v=1768917032\" alt=\"Fosi Audio IM4 Details\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/A35a25e36e32548589ec77d1fbc2ec73fJ.webp?v=1768916929\" alt=\"Fosi Audio IM4 Package\"\u003e\n\u003c\/div\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable class=\"specs\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eDriver Type\u003c\/th\u003e\n\u003ctd\u003e10mm Dynamic Driver\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eAcoustic Design\u003c\/th\u003e\n\u003ctd\u003eOpen-Back with Dual-Cavity Structure\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFrequency Response\u003c\/th\u003e\n\u003ctd\u003e20Hz - 40kHz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eImpedance\u003c\/th\u003e\n\u003ctd\u003e32Ω ± 15%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSensitivity\u003c\/th\u003e\n\u003ctd\u003e105dB\/mW (@1kHz)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCable Type\u003c\/th\u003e\n\u003ctd\u003eOFC Silver-Plated Cable (Non-detachable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCable Length\u003c\/th\u003e\n\u003ctd\u003e1.2m\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eConnector\u003c\/th\u003e\n\u003ctd\u003e3.5mm Single-Ended\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHousing Material\u003c\/th\u003e\n\u003ctd\u003ePremium Metal Alloy\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWeight (per earpiece)\u003c\/th\u003e\n\u003ctd\u003eApproximately 5g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSound Isolation\u003c\/th\u003e\n\u003ctd\u003eMinimal (Open-Back Design)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003ePackage Includes\u003c\/th\u003e\n\u003ctd\u003eIM4 IEMs, Ear Tips (S\/M\/L), Carrying Case, User Manual\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eFosi Audio IM4 Open-Back In-Ear Monitors (1 Pair)\u003c\/li\u003e\n\u003cli\u003eSilicone Ear Tips - Small, Medium, Large (3 Pairs)\u003c\/li\u003e\n\u003cli\u003ePremium Carrying Case (1 Piece)\u003c\/li\u003e\n\u003cli\u003eUser Manual (1 Copy)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSound Signature \u0026amp; Performance\u003c\/h3\u003e\n\u003cp\u003eThe Fosi Audio IM4 delivers a natural, reference-grade sound signature that showcases the advantages of open-back design:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBass:\u003c\/strong\u003e The dual-cavity structure provides deep, textured bass with excellent control and speed. Low-frequency extension is impressive, reaching down to 20Hz with authority. Bass is punchy and well-defined without the bloat or muddiness common in closed designs—perfect for all music genres.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMidrange:\u003c\/strong\u003e Transparent, natural mids with exceptional detail retrieval. Vocals are rendered with lifelike presence and texture, while instruments maintain their authentic timbre. The open-back design contributes to an airy, uncongested presentation that reveals every nuance.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTreble:\u003c\/strong\u003e Extended high-frequency response to 40kHz captures all the air and sparkle in your music. Treble is detailed and refined without harshness or sibilance, revealing micro-details and subtle textures that bring recordings to life.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSoundstage:\u003c\/strong\u003e The open-back architecture creates an exceptionally wide and deep soundstage that rivals over-ear headphones. Imaging is precise with excellent instrument separation and layering, making these IEMs ideal for orchestral music, live recordings, and complex mixes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDynamics:\u003c\/strong\u003e The 10mm driver handles dynamic contrasts beautifully—from whisper-quiet passages to explosive crescendos. The IM4 reproduces music with natural dynamics and effortless presentation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Choose Open-Back IEMs?\u003c\/h3\u003e\n\u003cp\u003eOpen-back in-ear monitors offer unique advantages that audiophiles appreciate:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eNatural Soundstage:\u003c\/strong\u003e The open design creates a more natural, speaker-like presentation with exceptional width and depth—far more spacious than closed IEMs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReduced Listening Fatigue:\u003c\/strong\u003e No acoustic pressure buildup means you can listen for hours without the fatigue common with closed designs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNatural Tonality:\u003c\/strong\u003e Less acoustic interference from sealed chambers results in more accurate, natural sound reproduction.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAiry Presentation:\u003c\/strong\u003e Music breathes naturally with an open, uncongested quality that's perfect for critical listening.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComfort:\u003c\/strong\u003e Reduced pressure on the ear canal provides superior comfort during extended listening sessions.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDual-Cavity Acoustic Technology\u003c\/h3\u003e\n\u003cp\u003eThe IM4's innovative dual-cavity structure provides significant acoustic advantages:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eOptimized Frequency Separation:\u003c\/strong\u003e Front and rear cavities are independently tuned to handle different frequency ranges, ensuring optimal performance across the spectrum.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEnhanced Bass Control:\u003c\/strong\u003e The rear cavity provides dedicated bass tuning, delivering deep extension with excellent control and minimal distortion.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eImproved Clarity:\u003c\/strong\u003e Separating bass from mids and highs eliminates interference and masking, resulting in exceptional clarity and detail retrieval.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNatural Resonance:\u003c\/strong\u003e Each cavity is precisely dimensioned to minimize unwanted resonances and standing waves.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv class=\"note\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Fosi","offers":[{"title":"IM4-Black","offer_id":47484328378607,"sku":"1005010322626273-IM4-Black","price":377.0,"currency_code":"PLN","in_stock":true},{"title":"IM4-Sliver","offer_id":47484328411375,"sku":"1005010322626273-IM4-Sliver","price":377.0,"currency_code":"PLN","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0626\/2004\/1455\/files\/fosi-audio-im4-10mm-dual-cavity-dynamic-driver-open-back-in-ear-monitor-earphone-4014333.webp?v=1768921783","url":"https:\/\/thehificat.com\/ja-pl\/products\/fosi-audio-im4","provider":"The HiFi Cat","version":"1.0","type":"link"}