HeadphoneOverreview

Fostex T50RPmk4

The modders' favourite planar finally got a new driver — and nearly everyone agrees it images brilliantly, while almost nobody agrees on how it should sound.

30 sourcesUpdated
$240Typical US price

Score aggregates reviewer opinions across topics.

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Fostex T50RPmk4

The short version

What to know.

A semi-open planar studio headphone on Fostex's redesigned 4th-generation RP driver. Sources broadly agree that localisation, separation and transient speed are its strengths, that it is far easier to drive than earlier T50RPs, that its bass now reaches deep without bloat, and that it is a functional plastic tool rather than a premium object. Tonality is genuinely contested three ways — neutral, slightly warm, or dry and lean — as are the midrange, the treble and the soundstage. A KEMAR-ear measurement explains much of it: bass and lower mids sit on target, the 2–4 kHz presence region falls about 9 dB below it, and a narrow peak near 8.4 kHz sits under a rolled-off top octave. Comfort and value split too, with headband and clamp complaints from a minority and a price argument from T50RP veterans. Pads move the sound more than on most headphones.

About this product

The semi-open T50RPmk4 (2024), on Fostex's 4th-generation RP planar driver — 28 Ω, 97 dB/mW, 3,000 mW maximum input, 10 Hz–40 kHz, approx. 330 g. It is not the 2016 T50RPmk3, the T50RP 50th-anniversary edition or the wood-cupped T60RP. Four siblings share its name and driver: the T50RPmk4g, a gaming-branded rebadge with identical specs and packaging; the T50RPmk4g+, which adds a detachable boom microphone; the closed-back T50RPmk4CL; and the T50RPmk4Q, whose stated change is 7N-grade internal wiring.

The Fostex T50RP has been the audiophile world's blank canvas for two decades: a cheap, unglamorous studio planar whose sound few people loved but whose driver everybody wanted, bought by the crate to be stuffed, damped, pad-rolled and re-cupped into Mad Dogs, Argons and the first ZMFs. The mk4, launched in Japan in spring 2024, is the first version in years to arrive with a genuinely new driver — a 4th-generation RP motor with more magnets and a redesigned coil pattern, at 28 Ω and 97 dB/mW instead of the old 50 Ω and 92 dB/mW.

Its second life came from an unexpected direction: Japanese competitive gamers adopted it for localisation, and Fostex answered with gaming-branded boxes around the same headphone. That leaves it reviewed by three crowds at once — studio engineers, long-time T50RP modders and gamers — who often come to opposite conclusions about the same unit.

A good fit for

  • Mixing and editing where placement and transient detail matter more than an enjoyable tilt
  • Competitive and immersive gaming, where its localisation is the main draw
  • Running from an audio interface, dongle or phone after giving up on power-hungry earlier T50RPs
  • Pad-rollers and modders who want the current RP driver as a starting platform
  • Tracking with some damping when a fully open headphone would bleed into the microphone

Think twice if

  • You are sensitive to a lean presence region — female vocals can sound hollow or distant on stock pads
  • You are sensitive to an 8–10 kHz peak, or want sparkling air above it
  • You want a finished headphone you will never re-pad, EQ or adjust
  • You need real isolation, or quiet listening that won't leak to people nearby
  • You already own a T50RPmk3 or T60RP and mainly want more weight and drama, not more speed

The reviewer consensus

Agreement &
disagreement.

6 / 12topics divide opinion
isolationbassimagingdetaildynamicsbuildtonalitymidstreblesoundstagecomfortvalue
1 Strong agreement5 Mostly agree6 Divided opinions

Common ground7

  • Localisation, separation and transient speed are the standout — the reason Japanese gamers adopted a studio headphone
  • Far easier to drive than earlier T50RPs at 28 Ω and 97 dB/mW: it runs well from audio interfaces, dongles and phones
  • The bass is deeper and fuller than earlier T50RPs without losing control

Points of contention6

  • Overall tonality reads as balanced and linear, as slightly warm, or as dry and clinical
  • Midrange reads as natural, as pushed forward, or as hollow and ringing through the vocal band
  • Treble reads as clean and non-fatiguing, as restrained and short of air, or as bright with an 8 kHz bite

A closer listen.

12 topics · 6 divided
Left: criticalRight: positiveTighter lines: more agreement

Tonality

Leans positiveDivided opinions
Reviewer sentiment20 supporting sources
CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

Sources split three ways: a balanced, linear monitor reading; a reading that hears it as slightly warm and smoothed; and a dry, lean, analytical reading. The measured curve is close to target through the bass and lower mids and deviates sharply on either side of 3 kHz, which leaves room for all three.

Measured

On Super* Review's KEMAR-ear (KB006x) rig, against that database's KEMAR-DF 10 dB-tilt target and normalised 200–1000 Hz, the curve sits within half a decibel from 50 Hz to 2 kHz, then falls about 9 dB below target across 2–4 kHz before a +4.6 dB peak near 8.4 kHz and a 10–16 kHz region about 6 dB down. Against an HD 600 on the same rig it carries about 4 dB more sub-bass and 9 dB less 2–4 kHz.

vs. listeners — The 'warm' and the 'dry' readings describe the same curve from different ends: the missing presence region makes it sound relaxed and unforced to some listeners, while the lean upper mids and the narrow 8 kHz peak make it sound dry and analytical to others. Source gear also shifts it — one owner found balanced drive colder and more fatiguing than a modest DAC.

Where it splits
balanced and linear, a true monitor38%

“Der gut angekoppelte und ausgewogene Mittenbereich schließt sich an und rundet die insgesamt lineare Wiedergabe ab.”

Harald Wittig, Professional Audio (German: “The well-coupled, balanced midrange follows on and rounds off an overall linear reproduction”)
slightly warm and smoothed28%

“they would be especially suitable if you are looking for comfortable, powerful and warm-sounding headphones for use over several hours”

Carsten Kaiser · headphonecheck.com
dry, lean and clinical34%

“The resulting timbre is very fast, dry and stale.”

GREQ · Head-Fi
Link to this topic

The hardware

Specifications.

Checked

Design

Type
Semi-open-back over-ear
Drivers
1 × planar magnetic (RP planar magnetic, 4th generation)

Electrical

Impedance
28 Ω
Sensitivity
97 dB/mW≈ 112.5 dB/V
Frequency response
10 Hz – 40 kHz

Connection

Cable
Detachable, single-entry, 2 m
Connector
3.5 mm
Plugs supplied
3.5 mm, 6.35 mm

Physical

Weight
330 g

Manufacturer-published figures, not measurements · from fostex.jp.

Follow the evidence

Sources 30

1–6 of 30 sources

Read with context

Limitations & method.

As of

What to keep in mind 6

  1. A read of where opinion sits in October 2026. Much of the detailed coverage is in Japanese and German, and the busiest English forum thread is only partly represented.

  2. Pads change this headphone more than most, and a lot of published impressions are of re-padded or modified units — check what someone had fitted before taking their tonal description as read. The foam ring behind the pad can also fall out during a swap and cost you bass.

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