Fostex TH909

High-End Open Headphones with Reference Capabilities

In a nutshell

The Fostex TH909 is ideal for hi-fi fans who are looking for a refined mid-range reproduction and demanding bass reserves, yet don’t want things too delicate in the highs. Whether or not the high price of these headphones will deliver value for money is up to the individual user. At any rate, it is obvious that any buyer is investing in an elegant piece of HiFi technology with a unique playback profile.


The Fostex TH-909 is a reference class headphone that’s out to impress with its open design. It is based on the TH900 mk2, but adds the benefits of an open system to its overall design. In our test, we aim to see how this all affects the overall sound quality of the system.

Headphone Stand Included

The large outer packaging of the headphones includes two separate boxes, one of which is matt black with gold Fostex lettering and the model name also lettered in gold. An adapter is unfortunately not included for the Fostex TH909 itself, but there is also a 3.15-metre cable with jack plug. A black carry bag with drawstring fastening is one of the accessory standards also included, with soft imitation leather and suede-style linings. However, the highlight here is the headphone stand, which is the chief reason these Fostex headphones are delivered in such a large box. The second inner carton contains the wooden headphone stand, painted in stylish matt black. Optional accessories for the TH909 include the balanced and XLR cables for the TH900 mk2. In addition, the ear cushions are replaceable.

Solid Wood, Ergonomic Form and Quality Cable


Visually, the TH909 replicates the design of the TH900 and can hardly be distinguished from it. Matt black dominates the headphones, with colourful accents provided by the ear shells, here made of Japanese cherry birch with a burgundy-coloured lacquer finish applied by Urushi craftsmen. A limited edition sapphire blue alternative is also available.

The earpieces are slightly angled to provide an ergonomic fit for the head. Undoubtedly, the headphones are simple, stylish and sophisticated at the same time. The headband and ear cushions are made of imitation leather, with steel braces and matt lacquered metal makes up the headband. All looks robust, yet elegant. Fostex has cut no corners with the TH909 when it comes to workmanship. The covers of the ear shells are handmade, with the imitation leather boasting internal seams, while the heavy-duty parts are fastened with screws for easy servicing down the line.

The oxygen-free copper cable should result in reduced internal resistance in the sound conductor. It is fabric sheathed and has a gold-plated stereo jack plug for protection against corrosion. The two contacts, which are inserted into the left and right earpieces, are rhodium-plated for the same purpose. Even if Fostex does not stress the detail here, audiophile circle chatter will tell you rhodium plating, with its very thin coating, should offer lower contact resistance compared to gold coating, thus resulting in higher sound quality.

Tech & Spec

Now onto the finer detail of the technical side of things. The Fostex TH909 uses dynamic 50 mm neodymium drivers with a magnetic field, with a notably high magnetic flux density of 1.5 Tesla. This is to guarantee ultra-precise reproduction, particularly in regards to deep bass and fine treble elements in the reproduced audio signal. These tonal characteristics are further enhanced by a “Biodyna” membrane, specially developed by Fostex. As a result, the TH909 offers an audio transmission range from 5 Hz to 45 kHz, along with a maximum sound pressure level of just under 100 dB SPL.

Heavy Duty

The TH909 sits comfortably on the head thanks to its ergonomic form and padding. Its size adjustment is rasterized, ensuring the previously used adjustment is locked in place until next needed. The ear shells can be rotated, swivelled and tilted, resulting in an optimal fit to any head shape. Due to the soft ear pads, users should not really have too much trouble with an overall model weight of 420 grams. Only when you shake your head does it become clear that the moderate contact pressure of the headband might make for some issues on the go. However, if you enjoy your music in a more sedentary situation, you won’t have any problems with it.

Sound Subtleties

When listening to the headphones, I instantly notice the striking highs. These ensure that users of the Fostex TH909 are given an impressive range of frequencies right into the super-high range, as well as a sublime signal resolution. The stereo image that is conveyed also benefits.

The mid-range, however, offers a rather hard sound that is not particularly velvety. You do have to appreciate the harder mid-range and treble sounds of the TH909, though. In addition to the obligatory boost at about 10 kHz (somewhat higher for these headphones than for others), a further boost of about 6 kHz is implemented as well. This does enhance speech intelligibility, but also means that many pop productions tend to hiss during playback with the TH909.

In contrast, the headphones appear more confident in the bass range. A well-balanced bass reproduction, right down to the deepest sub-basses, is the order of the day here. If the basses are increased on the amplifier side, it becomes clear what immense reserves the Fostex headphones offer in terms of bass. This is where its open design pays off, since it does not counter the bass pressure with any structural restrictions. At the same time, external noise insulation and attenuation capability, as is to be expected with open headphones, are relatively limited.

Across all frequency ranges, the playback signal remains distortion-free, even at higher volumes. Nevertheless, the sound quality of the highs soon becomes too much for sensitive ears. This also affects dynamics. Up to average monitoring volumes, however, the TH909 makes a dynamically flawless impression that is also strong in the highs.

4 years ago by Carsten Kaiser
  • Rating: 4
  • Sound
  • Handling
  • Price/Quality
  • Function

Measurement Results

Frequency response:

Exterior noise damping:
More measurement results

Technical specifications

  • Ear couplingOver-ear
  • Typeopen
  • Transducer principledynamic
  • Frequency response (headphones)5 - 45.000 Hz
  • Impedance23,6 ohms
  • Sound pressure level (SPL)99,38 dB
  • Pressure averaged from big and small head561,5 g
  • Weight with cable541 g
  • Weight without cable420 g
  • Cable length315 cm

What's in the box

  • Headphone stand
  • Bag

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