Fostex
Akishima, Tokyo, Japan · founded 1973
The T50RP is arguably the single most influential headphone in modding culture: its RP planar driver became the raw platform on which multiple boutique brands (ZMF, MrSpeakers/Dan Clark Audio) built their early businesses. Fostex is also the rare brand that spans OEM driver manufacturing (via parent Foster Electric), pro-audio recording gear, and summit-fi audiophile headphones under one name.
Fostex is the consumer and professional audio brand of Japan’s Foster Electric, one of the world’s largest OEM makers of speakers and transducers. Established in 1973 to market Foster’s high-quality driver components directly to consumers, dealers, and studios, Fostex is known in personal audio for its Regular Phase (RP) planar-magnetic drivers—most famously the endlessly-modded T50RP—and its flagship TH-series closed- and open-back dynamic headphones built around 50mm biocellulose/BioDyna diaphragms and hand-applied Urushi lacquered wooden housings (TH900 and successors).
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At a glance
- Type
- Manufacturer
- Founded
- 1973
- Headquarters
- Akishima, Tokyo, Japan
- Price range
- Budget → flagship
- Makes / sells
- headphones, headphone drivers, planar-magnetic drivers, loudspeakers, speaker components, multitrack recorders, field recorders, DACs/headphone amps
- Known for
- biocellulose/BioDyna dynamic drivers, Regular Phase (RP) planar-magnetic drivers, Urushi lacquered wooden headphone housings, modding-platform headphones (T50RP), studio/pro-audio heritage
- Website
- www.fostex.jp/en
Notable products
- Fostex TH900 / TH900mk2 — Flagship closed-back dynamic with 50mm biocellulose driver and red Urushi-lacquered wooden cups; long regarded as a 'basshead king' reference headphone.
- Fostex T50RP (RP-series planar) — Semi-open planar-magnetic headphone that became the most-modded headphone in the hobby; its RP driver seeded whole boutique brands (e.g., ZMF, MrSpeakers/Dan Clark).
- Fostex TH909 — Open-back sibling to the TH900mk2 flagship line.
- Fostex TH610 — Closed-back dynamic, successor to the TH600, birch-wood housing.
- Fostex TH910 / TH919 — Next-generation flagship closed-back (TH910) and open-back (TH919) launched ~September 2025, replacing the TH900 line; Japanese-lacquered maple housings with silver-foil patterning and updated 50mm BioDyna drivers.
Sources: Fostex - Wikipedia · History of Foster - Foster Electric Company, Limited · TH909 - Fostex (official) · TH910 - Fostex (official) · Fostex unveils updated flagship headphones (TH910/TH919) - NotebookCheck · Fostex T50RP Review - Major HiFi · Fostex TH900mk2 Reviews - Head-Fi