{"product_id":"fostex-t50rpmk4","title":"Fostex T50RPmk4","description":"\u003cdiv lang=\"en\"\u003e\n\u003cstrong\u003eFostex T50RPmk4\u003c\/strong\u003e is the fourth generation of the T50RP — one of the longest-running planar magnetic driver platforms in audio, used in studio monitoring environments since 1974. The mk4 is the first generation with a fully redesigned RP driver since the transition to the mk3: new printed coil pattern, increased magnet count, rebuilt magnetic circuit, and a new symmetrical housing with sockets on both sides. Impedance dropped to 28 Ω while sensitivity increased to 97 dB\/mW.\n\n\u003ch3\u003eWhat changed in the fourth-generation driver\u003c\/h3\u003e\nThe third-generation RP driver ran for nearly 20 years — from the mk3 in 2015 through the mk4's 2024 debut. The generational difference is substantially deeper than the mk2-to-mk3 transition, which was primarily a tuning revision on the same driver geometry. The mk4 introduces a redesigned printed coil trace pattern that expands and equalizes the diaphragm vibration area, increased magnet count sandwiching the diaphragm for stronger controlled drive, optimized magnetic flux distribution eliminating self-resonance modes, and a completely new housing geometry. The electrical result is measurable: impedance dropped from 50 Ω (mk3) to 28 Ω, and sensitivity rose from 91 dB\/mW to 97 dB\/mW — the mk4 drives adequately from an audio interface or portable source without a dedicated headphone amplifier, whereas the mk3 required substantial output voltage in the same context. Frequency response extends to 10 Hz – 40,000 Hz, compared to 15 Hz – 35,000 Hz on the mk3.\n\n\u003ch3\u003eNew cable topology and balanced connectivity\u003c\/h3\u003e\nPrevious T50RP generations used a left-cup-only proprietary connector. The mk4 introduces a 4-pole 3.5 mm TRRS socket on both earcups — the cable connects on either side with no tonal difference. Symmetrical housing eliminates the acoustic L\/R asymmetry caused by differing internal structures between sides. The 4-pole socket is balanced-capable from the factory — optional balanced cables ET-RP2.5BL (2.5 mm), ET-RP4.4BL (4.4 mm), and ET-RPXLR connect without adapters. The T50RPmk4 retains its status as a modding platform: ear pad swaps, internal damping modifications, and acoustic tuning remain viable, with a significantly higher stock performance baseline than the mk3.\n\n\u003ch3\u003eKEY FEATURES\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e4th-generation RP driver — new coil trace pattern, increased magnets, optimized magnetic circuit\u003c\/li\u003e\n\u003cli\u003e28 Ω impedance \/ 97 dB\/mW sensitivity — drives from audio interfaces and portable sources without a dedicated amplifier\u003c\/li\u003e\n\u003cli\u003eFrequency response 10 Hz – 40,000 Hz — extended vs mk3 (15 Hz – 35,000 Hz)\u003c\/li\u003e\n\u003cli\u003eSymmetrical housing with bilateral 4-pole TRRS 3.5 mm sockets — no L\/R acoustic asymmetry\u003c\/li\u003e\n\u003cli\u003eBalanced-capable out of the box — compatible with ET-RP2.5BL, ET-RP4.4BL, ET-RPXLR balanced cables\u003c\/li\u003e\n\u003cli\u003eSemi-open design — acoustically unified with T50RPmk4CL closed-back platform\u003c\/li\u003e\n\u003cli\u003eLow-rebound circumaural ear pads — optional Ultrasuede EX-EP-RP60 available separately\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTECHNICAL SPECIFICATIONS\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eModel: T50RPmk4\u003c\/li\u003e\n\u003cli\u003eDriver type: Planar magnetic RP (Regular Phase), 4th generation\u003c\/li\u003e\n\u003cli\u003eDesign: Semi-open\u003c\/li\u003e\n\u003cli\u003eImpedance: 28 Ω\u003c\/li\u003e\n\u003cli\u003eSensitivity: 97 dB\/mW\u003c\/li\u003e\n\u003cli\u003eFrequency response: 10 Hz – 40,000 Hz\u003c\/li\u003e\n\u003cli\u003eMaximum input power: 3,000 mW\u003c\/li\u003e\n\u003cli\u003eEarcup connectors: 4-pole 3.5 mm TRRS (symmetrical bilateral)\u003c\/li\u003e\n\u003cli\u003eWeight: approx. 330 g (without cable)\u003c\/li\u003e\n\u003cli\u003eIncluded accessories: OFC cable 3.5 mm (4-pole to 3-pole, 2 m), 3.5 mm to 6.3 mm adapter\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e","brand":"FOSTEX","offers":[{"title":"Default Title","offer_id":53693023650129,"sku":"59491","price":0.0,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0729\/8741\/0769\/files\/FostexT50RPmk41.jpg?v=1777977067","url":"https:\/\/wrdtunes.com\/fr\/products\/fostex-t50rpmk4","provider":"Wired Tunes","version":"1.0","type":"link"}