Fostex T40RP MK3 Professional Studio Headphones

First off, there's a lot of misunderstanding on this venerable Magnetic Planar. The Foster drivers used in it has been in existence for over 30 years, and it has been refined many times over since then. Among the three Magnetic Planars that I own now, I love this T40RP MK3 the most, and here's why:

- Driving Power & Transparency. At 91db of sensitivity (despite with just 50 Ohm impedance) this planar need tons of juice to sound great. Yes it may not be as difficult to get loudness but if the quality of the source is just mediocre then rest assured the quality of output is mediocre too. For example even the AudioQuest DragonFly Cobalt can drive this T40RP to max volume at 70/100, however the quality is nowhere near pleasurable because evidently the spectrum of sound delivered were severely lacking in terms of dynamic range, timbre coherence and stability. It was jittery and outright nasal sounding on the Mids. Anyone hearing this would then automatically think this T40RP sucks. Similar results if plugged to any laptop, the volume loudness will not be hard to achieve, but the sound is yet again far from being enjoyable - jittery edged and anemic, lacking depth and texture. I have also observed that with my 4 Vrms iBasso DC04, which was supposed to be one of the most powerful DAC/Amp in my collection, the sound was very edgy and sibilant prone - Treble can get hot with peaky sheen that hurts the eardrums. I conclude that this may be the case that DC04 was trying hard to overcompensate amplification to satisfy dense low sensitivity of T40RP - which in the end failed miserably.

It is actually the source that made it sound bad. The same T40RP when plugged to a properly designed DAC/Amp like Ovidius B1, Hidizs S9 and S9 Pro on the other hand exhibited wholesome sound that is free from any sort of distortion or timbre instability. Dynamic range also gets wide as it is vibrant. I can clearly hear how far reaching the bass and treble extension goes with proper textures and smooth decays.

As a reference, I always use my Shure KSE1500 for transparency and resolution. Among the three magnetic planars I owned the T40RP MK3 matches closer to what that extraordinary Electrostatic unit offers. Shure KSE1500 does not have its own signature, as how a true transparent and resolving high end reference grade listening device should behave. KSE1500 will present the sound as how the source projected it to the fullest and reveals everything. If the source is bad then the output is bad. If the source lacking dynamic range then the extensions fall short. T40RP behaves similarly. It is very transparent and revealing.

- Tonality and Timbre. T40RP is something I regard as Neutral Balanced, as opposed to Flat Neutral exhibited by my Etymotic ER4SR which is more truthful to Diffused Field Neutral. What it means, when T40RP is powered and driven by an equally neutral balanced source, the output is nothing short of breathtaking. If I want it to be euphonic or warm, I switch to a warmer source like the AKM based Hidizs S9 or VE Odyssey HD. If I want it to be sparkly bright, I switch to ESS Sabre based hiliDAC Audirect BEAM 2SE. This alone exhibited how versatile T40RP is to the nature of the feed it receives.

- Comfort. Admittedly the stock pads are NOT comfortable. I was unable to wear it past 1 hour mark. The smallish and thin pads behaved like Over-the-Ear instead of full Circumaural headphone. The solution was simple, I replaced it with my spare Pleather Pads that was originally intended for my Beyerdynamic DT990. They fit in just nice with tight tolerances despite T40RP being oval shaped. Now I am able to wear my T40RP for over 4 hours straight without inflicting misery to my ear lobes.


Mods - You cannot separate the word "Mods" from FOSTEX T series. They are designed to be 100% modular and can be easily disassembled by anyone without the need to be a rocket scientist. For my own T40RP MK3 I have opted to mod just the cabling section to allow it for Balanced feed. So I DIYed and adapted MMCX ports that will then allow me to use my existing cables and jacks - easily swapping between OFC/SPC, 2.5mm, 4.4mm and 3.5mm SE. I need this versatility to use it with over 20 units of DAC/Amps that I own now. I opted to run everything else stock for now as I am quite satisfied with the stock sound it provide as described earlier.


VERDICT
I immensely love this FOSTEX T40RP. It does have quirky character that can be frustrating to deal with - but then, that is the nature of a true transparent sounding headphone. Pair it well and it will not fail to impress. Scalability of T40RP is what makes it great (just like the Etymotic ER4SR, Shure KSE1500 and TIN HiFi P1). T40RP does not pretend to be something it is not, it is merciless to poor source and will revel the glory of a great one.

Great build, robust, 2nd only to DT770 Pro. Love the looks. 3.5mm to 3.5mm cable with locks on both sides. Nice and practical. Medium to light weight at 315g. I have often found advices that these “need nuclear powerplant to drive”. I guess that probably sprung from the specification that they can take up to 3 Watts of power. However, I found them relatively easy to drive. I found no issue driving them from phone, tablet or laptop to impressive loudness. Sound is, there is no other word, smooth, comparing to the dynamic drivers. Like it’s missing the kind of grainy background that I notice on the dynamics. This model is exceptionally tuned, between 80Hz and 5kHz it has great adherence to the target. Sub-bass is rolled off and treble attenuated, but that is almost wholly fixable with EQ. They also sound great without any EQ. Bass sounds impressive, big and strong, maybe a little boomy but without overwhelming mids much. Thin pads puts the driver near your ear for best sound quality. Unfortunately, this bring us to comfort. Thin pleather pads and headband coupled with strong clamp makes them somewhat uncomfortable and sweaty, especially during hot months. Great entry to planar headphones and probably the best closed back HP for the price.