HeadphoneOverreview

Fostex TH900mk2

Bass, speed and lacquer that nearly everyone praises — treble, mids and hinges that nearly everyone argues about.

41 sourcesUpdated
$1,400Typical US price

Score aggregates reviewer opinions across topics.

Check price on Amazon
As an Amazon Associate, we earn from qualifying purchases.
Fostex TH900mk2

The short version

What to know.

A closed-back dynamic flagship with a deliberately V-shaped tuning that every rig measures the same way: a sub-bass shelf roughly 5 dB above the Harman target (14–19 dB above an HD 600 at 20 Hz), a dip through the lower mids and presence, and a 5–6 kHz peak roughly 7–12 dB above an HD 600 measured on the same rig, depending on unit and rig. Sources agree on what that buys: the deepest, cleanest, fastest bass most of them have heard in a headphone, excellent dynamics and detail, a wide stage for a closed-back, very easy driving and poor isolation. They split on the rest. Most measurers and many owners hear the treble as hot, sibilant or fatiguing and the midrange as thin; a smaller group hears exciting sparkle; and the limited-edition 'anniversary tuning' measures and sounds tamer. Reviewers praise the build while owners report hinge and headband breaks, the loose clamp divides opinion on comfort, and most sources doubt it is worth flagship money. Pads, amp and EQ change it a lot.

About this product

Closed-back dynamic flagship on a 50 mm BioDyna driver (25 Ω, 100 dB/mW, ~390 g) in Japanese Cherry Birch cups finished in Urushi lacquer. The mk2 (2016) differs from the 2012 TH900 only by its detachable 2-pin cable. Fostex now lists it as discontinued, succeeded by the redesigned TH910; new stock lingers at about $1,400 and used pairs sell for $600–800. The standard colour is Bordeaux red; the limited editions (Sapphire Blue, Pearl White, Onyx Black, Brilliant Purple) use an 'anniversary tuning' that measures roughly 3 dB less bass and less 5–6 kHz peak than the standard red.

The Fostex TH900 arrived in 2012 as the closed-back flagship of Fostex, the audio brand of Foster Electric — the Japanese maker behind Denon's wood-cupped D2000/D5000/D7000. Its 50 mm BioDyna driver sits in Japanese Cherry Birch cups finished in deep-red Urushi lacquer, and in 2016 the mk2 added a detachable cable and changed nothing else.

A decade on it is one of the most recognisable headphones ever made and one of the most divisive: the bass and the dynamics are a reference point for bassheads, while the treble made one of the hobby's best-known measurers write 'These suck.' Fostex has now discontinued it in favour of the TH910. This rebuild draws on 41 sources — six measurement rigs, the full 111-page Head-Fi thread, both Head-Fi showcases, sixteen Reddit owners and critics, and Amazon buyers.

A good fit for

  • Bassheads who want deep, clean sub-bass slam from a closed-back — the aspect almost every source rates highest
  • Electronic, hip-hop and pop listeners who like a lively V-shaped tuning
  • Listeners who value dynamics, speed and a wide closed-back stage over neutral tonality
  • Owners willing to swap pads, EQ or pair a warm amp to tame the treble and fill the mids
  • Buyers who can find an anniversary-tuned limited edition or a good used pair, which fix the treble or the price

Think twice if

  • You are treble-sensitive — most sources, and every rig on the standard red, find the 5–6 kHz peak hot
  • You want natural vocals and a full midrange for jazz, classical or acoustic music
  • You need isolation or a secure fit on the move — it leaks and the clamp is loose
  • You're rough on gear — owners report hinge and headband breaks over the years
  • You want a current, supported model — it is discontinued, and the TH910 replaces it

The reviewer consensus

Agreement &
disagreement.

7 / 12topics divide opinion
isolationsoundstageimagingdetaildynamicsbassmidstrebletonalitycomfortbuildvalue
1 Strong agreement4 Mostly agree7 Divided opinions

Common ground6

  • The bass is huge, deep and fast — the one thing nearly every source praises, even its harshest critics.
  • Dynamics and slam are among the best in any headphone; detail and speed rank near far pricier open flagships.
  • Wide and open for a closed-back, with precise imaging and separation.

Points of contention7

  • Treble: hot and fatiguing (most sources, standard red) vs extended sparkle vs tamed on the anniversary-tuned limited editions.
  • Tonality: a flawed V that swamps the mids vs a fun, engaging colour vs near-balanced on the limited editions.
  • Midrange: recessed and thin vs laid-back but clean.

A closer listen.

12 topics · 7 divided
Left: criticalRight: positiveTighter lines: more agreement

Bass

PositiveDivided opinions
Reviewer sentiment31 supporting sources
CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

Sources split three ways on one very large bass shelf. The large majority — unheardlab, MajorHiFi, GREQ, Z Reviews, ishca, hanouk and most owners — call it the headphone's calling card: deep, clean, fast and hard-hitting without bleeding into the mids. A minority led by Crinacle hears it as bloated or boomy, especially at volume. A third group of owners hears the opposite: less bass than the reputation promises. Some of that group trace it to a weak seal from the loose clamp, worn pads or a small head, since a leak cuts bass on a headphone this loosely clamped.

Measured

oratory1990 (GRAS) measures the standard unit about 5 dB above the Harman target from 50 to 200 Hz; against the HD 600 on the same rig it is 14 dB louder at 20 Hz and 6 dB at 100 Hz. unheardlab, InnerFidelity and Crinacle show the same shelf (16–19 dB over the HD 600 at 20 Hz, 6–9 dB at 100 Hz); kr0mka's unit is milder. The anniversary-tuning LEs measure about 3.5 dB less at 100 Hz than the standard red on the same rigs.

vs. listeners — Every rig shows a lot of bass, so the 'not that boosted' camp is not describing the graph. Two things explain it: the clamp is light, so a poor seal on a smaller head loses bass, and the scooped lower mids plus the hot treble make the bass sound leaner than the numbers. The limited editions also carry less of it.

Where it splits
Deep, clean, fast and physical — the best bass most sources have heard from a headphone77%

“It does bass amazingly though, even better than the Teak one could say.”

unheardlab
Too much — bloated or boomy, and it crowds the midrange13%

“Spicy sibilance and bloated bass are disappointments in what is otherwise an extremely dynamic headphone.”

Crinacle (headphone ranking list)
Less than its reputation — clean, but not the bass cannon people expect10%

“Fact is they are quite thin sounding and the bass isn't really that boosted.”

Reddit — r/headphones (STXDakota, 9-month owner)
Link to this topic

The hardware

Specifications.

Checked

Design

Type
Closed-back
Drivers
1 × 50 mm dynamic (Biodyna diaphragm)
Housing
Japanese Cherry Birch, finished by Japanese traditional "Urushi" lacquer

Electrical

Impedance
25 Ω
Sensitivity
100 dB/mW≈ 116 dB/V
Frequency response
5 Hz – 45 kHz

Connection

Cable
Detachable, 3 m
Connector
2-pin
Plugs supplied
6.35 mm

Physical

Weight
390 g

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

Follow the evidence

Sources 41

1–6 of 41 sources

Read with context

Limitations & method.

As of

What to keep in mind 6

  1. A read of where the reviews land as of September 2026. The TH900mk2 is now discontinued and replaced by the TH910, so most of the evidence is years old, and much of the buying now happens on the used market.

  2. Which TH900 you hear matters: the standard Bordeaux red measures as the most V-shaped, while the anniversary-tuned limited editions (Sapphire Blue, Pearl White, Onyx Black, Brilliant Purple) measure noticeably tamer. Some verdicts here come from those editions.

Where to buy Product & retailer links

As an Amazon Associate, we earn from qualifying purchases.