Pros: Awesome value for money with the sound it produces for its price. A more transparent and clearer tonal signature compared to it's predecessor.
Cons: Treble sensitive audio listeners could find it a little "hot". Still lacking in sub bass.
A great thank you to Fostex Japan for graciously passing me this T50RP Mk3 and giving me the opportunity to write this review. Further a great big thanks to @Wallabee for loaning me his T50RP Mk2 for a comparison.
Fostex T50RP models actually require no introduction as it's been a running model since 2002 (with a revision around 2007). And in 2015, Fostex has done a 3rd revision of the T50RP. The RRP in Japan is 20,000 yen (equiv to USD$161).
Unlike it's predecessor, the Mk3 is more easily identifiable with changes to the text & colour of the labels, a padded headband. Strangely just such tiny little changes does make the headphone look more fashionable. Internally however, the Fostex has made some changes that does make the headphone sound like a different model altogether. The diaphragm is still the same but the ventilation portion and the baffle has been re-designed.
There are a few traits that keep that "Fostex T50RP" house sound however the tonality of the T50RP has changed significantly. But more about that later.
Package and Ergonomics
As with the Mk2, the T50RP Mk3 includes a 3m long black cable terminated with a 1/4" plug. In addition, it comes with a shorter 1.2m orange cable terminated with 3.5mm locking plug. The shorter cable is actually more practical for portable use. Ergonomically the Mk3 is just as comfortable as the former. Despite the headband being padded, personally for me it hasn't really made much of a difference from the former in terms of comfort. The Mk3 weighs at 316g and is about 10g lighter than the Mk2.
T50RP Mk3 Headband
The headband differences between the T50RP Mk2 and Mk3
T50RP Mk3 earpads
The firmness seems to be very similar but design-wise has changed. The Mk2 pads were made from regular urethane whilst the newer is made of low repulsion urethane. Design-wise, notice how the flange of the older (right) goes over the rim of the up of the cup, whilst the newer (left) is more like the TH-900/TH500RP style.
As always, this is what we're here for. Firstly my setup is having Audirvana Plus 2.1.1 running off my iMac USB3 into my Aurender Flow. There I have a splitter to run both versions of the T50RP concurrently. Although there's been criticisms about the T50RPs needing amping, I've actually managed to drive the Mk3s (and Mk2's) reasonably off the iPhone 6 whilst the iPhone 4s may seem to struggle just a little bit more. Further with the tonal differences between the Mk2 and Mk3, the latter "feels relatively easier" to drive at least to my ears. However, I've been accustomed to using my Aurender Flow included as my base reference recently and continue to do so with the impressions of this Fostex model.
So tonally, to my ears, the T50RP Mk3 feels more natural than the Mk2. It's reminiscent of the Alpha Dogs although there's sufficient differences that gives the T50RP Mk3 its own identity. Comparing directly to the Mk2, the newer Mk3 seems to have a tighter bass, a veil lifted in the midrange to lower trebles range, and the transition from the upper midrange to the lower treble range feels more uniform whilst the older Mk2 seems to me to have a little treble rolloff. There is one common feature in the treble range of both the Mk2 and Mk3 that reminds me they're both from the same Fostex family, and that is a bit of a 10kHz hump/spike. This is more noticeable in the Mk2 as the treble is more rolled off, then an unexpected "spike" around the 10kHz range. The Mk3 also seems to have that but as the trebles aren't rolled off, the spike isn't as obvious.
The midrange of the T50RP Mk3 also isn't as prominent as the Mk2. In fact comparatively the Mk3 feels there's a slight dip to the midrange. However this makes the Mk3 signature to be an overall easier signature to like.
The bass is part that I do like in the T50RP Mk3, where I feel Fostex has taken the effort to clean up the bloom that the T50RP Mk2 had. The midbass bloom seems be tighter and the speed of the T50RP drivers is more noticeable. The sub bass is lacking however I don't personally don't really miss it.
Aside from it's tonal signature, it provides a decent soundstage. It's not as wide as it's TH-900 cousin however does give the perception of a wider soundstage than it's predecessor Mk2s. Similarly for it's depth imaging. I can't help to think (and having experienced the Alpha Dogs) the cup size and dampening used of the T50RP plays a part in how it presents the stage. However again, the Alpha Dog is a complete rework and a further 3x the cost of the T50RP Mk3s.
Detail retrieval to me is one of the most I've personally heard in a $200 (or even $300) headphone. Of course there are other headphones with miro detail-level retrieval performance however those headphones are priced rather differently. This is where I feel the T50RP drivers do really reveal their capability.
I think Fostex has done a fantastic job in improving the long running T50RP name. This is a marked upgrade (and probably a long overdue) over the T50RP Mk2. I can't help to speculate that Fostex has been sitting on the sidelines a little too long watching what other makers could do with its T50RP drivers and selling their versions of the headphone at 2-4x the price.Now the T50RP Mk3 can get a piece of that action too without increasing its price line too differently. Whilst I'd dare say the Mk3 still isn't an Alpha Dog, they are tonally closer than the Mk3 is to the Mk2; yet price wise it's much closer to the Mk2 sibling than the no longer produced Alpha Dog.
For the price and the sound quality it produces, T50RP Mk3 stands on its own. Should any maker decide to continue using the T50RP drivers, they'd need to consider how to keep their mods more competitive.