Fostex TH-909 Premium Open-Back 1.5 Tesla Stereo Headphones

-2018, a strange year for headphones- Foster Electronics, Fostex’ parent company, have a storied history as a technology leader for closed back headphones. They provided the drivers for the legendary Sony R10 , they were the OEM manufacturer behind the original Denon D2000/5000/7000 models and their headphones have been the platform for an entire industry of professional modders (ZMF, Mr. Speakers, Modhouse etc). Recently, Fostex produce their own high end, top of the line closed backs, the TH900. It was strange, then, to hear Fostex announce this new flagship OPEN BACK headphone. Bizarrely, Sennheiser - the German shop that invented the open back headphone - released their own new flagship closed back HD820 in 2018 as well, in a similar twist. In both cases, this inversion of the brand identity is at the heart of the mixed reaction to the product. Indeed, I myself had conflicted feelings about Fostex’ decision to lop off the cap of the TH900's beautiful Urushi lacquer cups and replace it with a (striking!) dual layer open grille. The re-tuned voice circuit intrigued me enough to try, however. I am pleased to report that the dual layered grille adds some substantial technical benefits to this headphone, but also that the sonic re-tune makes for a highly complementary headphone. -Impressions- Physically, there is a great deal of similarity between this product and the TH900. They feature the same Urushi lacquer cups (so gorgeous!), and come with a similar list of accessories. The wooden stand to display your headphone treasure is much appreciated, although I did miss the nice product story brochure that came with the TH900. None of the TH series have inspired a great deal of confidence in me for build quality, definitely coming across as quite delicate - that said the headband slider does feel a little more substantial on this new TH909 (and is also about notch smaller, FYI), and I have had no issues with any of my own TH models. Sound wise, these are something of a departure from the signature V shaped profile Fostex is known for. The updated tuning has added a significant boost around 500 Hz, where the 900 had a null. This is an extension of the VERY heavy bass emphasis on both models, and results in an incredible full sound on the 909 extending up into the mids. The upper mids, and highs however are highly consistent with the Fostex tuning. Compared to most tuning, these have recessed output between 1-2KHz. They also have a similar ~6KHz spike and a generally brighter emphasis in the high mids above 3 kHz. The result is a sound signature that is full bodied for acoustic and vocal recordings, while still retaining the signature high freqeuncy sparkle that Fostex is known for. The bass output is similar amplitude, however the higher mids on the TH909 mean the perceived bass is lower than that of the TH900. The mid boost can also border into 'shouty' on some recordings, however these are wonderfully capable for EQing if you feel the desire to compensate: -Technical Performance- Measurements of these headphones are sparse, but they show excellent performance. Fostex’ Biodynia diaphragm has always shown exceptionally low distortion (trivial), but the 909's new dual layer open grille has done an excellent job retaining the phase information for the listener. Phase refers to the relative maxima and minima of a particular frequency waveform. Humans use the phase information in sound to understand positioning data of the sources - generally the phasing will correspond to the time of arrival which we are evolved to be very sensitive to. A uniform phase response in a speaker means that the transducer won't add spatial coloration, and instruments will be tightly resolvable in a good recording. These TH909 exhibit phase uniformity within about 10 degrees, which is very impressive for a dynamic transducer. Compare this to about 20 degrees for the Sennheiser HD800s, and about 50 degrees for the Focal Utopia - similar open backed flag ship cans. This is particularly impressive given how low impedance the Fostex 909's are - 300 ohms for the 800s, 85 ohms for the Utopia and only 25 ohms on the 909. Phase uniformity can generally be improved by using a thicker copper coil (higher impedance, more resistance relative to the parasitics). The Beyerdynamic DT880 has excellent phase uniformity in its 600 ohm version for instance, but quite a bit of variation in 32 ohms. [Check out Tyl's measurements at Innerfidelity and also Brent Butterworth's at SoundStrageNetwork for the 909 measurements] -Amplification- A great deal of speculation surrounds the pairing of these with different amplifiers, and they do present a challenge to conventional audiophile 'wisdom' in this respect. As audiophiles, we are unfortunately largely drawn to higher power output when it comes to amplifiers. Many audiophile dynamics are indeed high impedance (see above rant on phase), so generally this trend is OK, but for a low impedance like the TH909 this actually poses quite a challenge for an amplifier. Amps feed current to the headphone, the level of which will depend on the impedance of the headphone and the power rating of the amp. A high impedance load means that not much current is required from the amp to deliver its power rating. A low impedance however, will draw tons of current (if you follow the trend to zero, you are essentially approaching a short circuit), which risks over-saturating otherwise mighty high powered amps. A low impedance like the 909 risks oversaturating the amp, but it will also present this scenario in a particularly unflattering way. The harmonic distortion that this introduces in the source signal are emphasized by their relatively bright high frequencies. With this in mind, when it comes to amping these - less is more for power rating. Fostex themselves sell several nice options (I have been feeding these and my TH900's from the HPA-4BL pictured), but I have also found my lean little IFI nano Black Label sing nicely. In contrast, I keep my THX for high impedance / less sensitive loads. -The bottom line- Frequency response wise these may not work as a jack of all trades, their performance is such that you can EQ them into just about anything you want while retaining transparency. I for one, really like the signature. Highly recommended!

These are great headphones. They look beautiful and they are very comfortable. Compared to the Audeze LCD-MX4, which is what I have been using, the most obvious difference is the much more prominent bass.

Was choosing between HD800 and TH909. After testing both, decided for the 909s

If you like an emphasis on bass (thump, thump), and/or a V-shaped sound, this is it. The fact that they are also gorgeous (more so in person) is an added bonus. You can't not want to display these in a place for everyone to see. Get 'em people. Unfortunately, I just ended up not being to afford them so I had to send them back. To make that happen I have a little savings account.

I guess you are wandering the reviews of this headphone because your expensive cans are leaving something to be desired in the low end. Look no further. Articulate accurate bass is here for the audiophile. These are not a bass headphone. They just have the ability to recreate the lows which gives a rich sound to the majority of music in existence. That being said these head phones are very agile. The only knock is the high end seems a touch elevated. But nothing to be concerned about. Never harsh. I actually find it pleasing for this headphone. And besides, I have other head phones for reference/ analytical listening. Who says audiophile headphone have to have a stick up their butt? Even these are " open back" they are semi open back, so the sound stage isn't as wide as a true open back. Not as dynamic as LCD XC Retrieval is very good. Not great. Head phones are very light and comfortable

CAUTION.. I am giving this a 5 star review but in all truth it should be 4. These are the most amp dependent headphone I have ever used. I have found my cheaper portable amps or like the xduoo xd05 or oppo ha2 push these correctly vs the aune s7 or rme adi2. More expensive is not the solution. It is a complete crap-shoot. These are either amazing, warm, bassy, wide OR narrow, weak and sibilant depending on the amp. I have never gone through this before except HD800 and not to this extent.

Mise en garde: Prenez le temps d’aller écouter longuement votre sélection de casques audiophiles (même si comme moi vous ne pouvez pas certains vous les payer à bien plus de 2000€, mais bien les écouter pour comparer avec des Stax, Focal, Audeze et Hifiman comme références acoustiques!) et surtout avec vos préférences musicales. Vos oreilles n’étant pas les miennes et vos gouts musicaux surement bien différents. Mon choix c’est finalement porté sur le Fostex 909 , car j’hésitais longuement avec l’Audio Technica ATHADX5000 en équation avec toutes mes écoutes et mon budget, une promotion à moins de 1700€ quasiment au prix d’un excellent Hifiman HE (V2) 1000-Stealth acoustiquement mais à l'esthétique particulière m’a convaincu pour cet exceptionnel rapport qualité/prix. Soleil couchant: L’écoute de ce casque audiophile donc uniquement de salon pour moi se faisant les yeux fermés pour être pleinement dans cet "espace musical incroyable" avec de véritables basses savoureuses comme un vrai régal de tout le reste de la bande passante. Soleil levant: À la sortie du plaisir, voir de la jouissance acoustique, vient le plaisir visuel, un casque magnifique quasiment une œuvre d’art dans la pure tradition japonaise, c'est pour cela qu'un écrin à ce bijou n'est pas nécessaire pour le cacher des yeux... Conclusion: Une belle écoute à toutes et tous. Un casque ultime qui surclasse le déjà excellent Fostex 900 casque fermé, la spécialité de cette marque Fostex jusqu'à ce 909 qui est pour moi un semi-ouvert, il a les excellentes qualités de ses très petits défauts (trop faible résistance) comme tout bon compromis acoustique. Casque très fidèle et à effet stéréo prononcé, idéal pour l’écoute des vinyles d’origines...