Fostex T50RPmk4

In 2023, we found the anniversary edition of the previous model Fostex T50RPmk3 (Test) to be impressive. Now, the fourth generation of these over-ear headphones offers not only innovative ways of connecting the cable but also technical advancement of the drivers, which will further improve the dynamics and volume of these headphones.

Fostex T50RPmk4 – Package and design

The Fostex T50RPmk4 arrives with just the essentials. In addition to the headphones themselves, there is a two-metre-long high-quality OFC cable with 3.5mm jack plugs and a matching 6.35mm jack adapter included. There is a 4-pin 3.5mm socket on the headphones, and this supports symmetrical operation. Suitable cables for symmetrical operation can be purchased separately.

On this mk4 version the exterior of the T50RP is now completely black. This affects the cables, which on the mk3 were in the typical bright Fostex orange. However, the vertical struts of the headband are now also matt black. The design of the earcups has also been changed. The socket for connecting the interchangeable cable has been moved to the centre of the earcup and is no longer clearly visible on the outside. Instead, there is a simpler version on the underside. In addition, the left/right labelling has been moved from the ear cups to the headband. All of this ensures that these latest headphones are much simpler and have a more futuristic look.

Material and technology of the Fostex T50RPmk4

As usual, Fostex uses plastic ear cups and imitation leather for the headband and ear pads. If you are seeking high-quality components and precision down to the last detail in the appearance of your studio headphones, you won’t find it here. The magnetostatic Regular Phase (RP) drivers have been redesigned for this fourth-generation model. The coil structure of the diaphragms has been improved to increase their vibration range. In addition, the magnets now have a higher overall flux density. This should enable a stronger magnetic field and thus improve the dynamic reproduction.

Improved technical values of the Fostex T50RPmk4

As a result, with the mk4, the specifications of the Fostex T50RP have been significantly improved. The frequency range has been considerably extended both in the bass range and in the treble range. With a low bass range extending down to 10 Hz, these headphones are also suitable for reproducing the deepest sub-basses. And, on paper, a super high-frequency range extending up to 40 kHz leaves little to be desired. However, the truth is that comparable planar-magnetic headphones from other manufacturers sometimes beat this kHz value. With its reduced impedance of 28 ohms, the T50RPmk4 is now even better suited for use with headphone outputs with a low output voltage, such as those typically used for audio interfaces and smart devices. The sensitivity of the headphones has been increased to 97 dB/mW, enabling louder undistorted playback than the mk3, so it can now compete with that of rival models.

The Fostex T50RPmk4 offers high wearing comfort

The headband of the Fostex T50RPmk4 automatically adjusts to the size of your head when you put it on. However, if you are particular about the symmetry of the fit, you will need to readjust these headphones with both hands. However, once positioned, the fit of the headphones was excellent. The padding on the headband was sufficient, and the ear pad’s memory foam ensured a great fit. The combination of pressure from the headband and the weight of the headphones was almost perfect. The headphones sit securely without pinching, even when moving your head around quickly.

An interesting feature of this model is that the cable can be plugged in either on the left or right. This makes it one of the few headphones models available that is ideal for left-handers.

The fact that on the mk4 the sockets for connecting the interchangeable cable are located in the centre of the underside of the ear cups means that the cable is now less close to your shoulders. This is a practical touch. While the previous model offered a locking mechanism for the plug, the cable plugs into the mk4 without any retention mechanism. It would have been nice to have some kind of bayonet mechanism here. One positive aspect was the length of the cable, which at two metres was ideal for my studio listening set-up.

How do the Fostex T50RPmk4 sound?

The treble reproduction of the Fostex T50RPmk4 was warm and restrained and the super high-frequency range was also rather restrained. This made the overall sound a little muffled. Vocals and guitars were prominent in the mid-range reproduction but never became too cutting. If you are looking for headphones that prevent you from mixing vocals too loudly or want to prevent hearing fatigue when listening to distorted guitars for several hours, these would be the right choice. Even the dreaded sibilance of s-sounds was no problem with the mk4.

If required, these headphones can also be used to reproduce the deepest low basses powerfully. From synthesiser basses in EDM and ultra-deep kick drums in urban music to low-frequency sound design, everything can be assessed with this model.

As befits magnetostatic headphones, the T50RPmk4 also has strengths in the dynamics. The dynamic image differentiation ranged from good to satisfactory, with percussive transients being reproduced as broad rather than pointed. Due to its rather ‘busy’ sound in the highs, the signal resolution was rather ordinary. That said, the volume of these headphones was impressive. You could confidently describe the reproduction as ‘powerful’.

Conclusion

The semi-open, circumaural Fostex T50RPmk4 offer a high level of wearing comfort. In addition, the combination of revised magnetostatic drivers and improved cable routing ensures both an extended frequency range and solid dynamic reproduction. The fact that the cable can be plugged in either on the left or right makes these headphones suitable for left-handed users. For studio use, they were particularly good for assessing and mixing cutting mids but can also be used to monitor the deepest bass frequencies. I was satisfied with the price-performance ratio of the Fostex T50RPmk4; they would be especially suitable if you are looking for comfortable, powerful and warm-sounding headphones for use over several hours.