Fostex T50rp Review – Modified DIY Headphones

Why make your own DIY modified Fostex T50rp Headphones?

The Fostex T50rp is one of these headphones that benefits immensely with a little user modding and can be tailored to the exact sound specification you require whether it be treble or bass.  It is a planar headphone which I won’t go into too much detail right now and may do a separate article on.  Orthodynamics are used in some of the world’s best-sounding headphones, particularly in Audeze’s LCD range to much fanfare.  What you get with the Fostex is that same technology in the driver in a package that when tweaked comes very very close to that of an LCD2 or LCD3.

Making my modified DIY Fostex T50rp Planar Magnetic Headphones

I have sets of this particular phone and have spent months tweaking to get it where I want.  

Naked Driver

Paxmate Cup

Cotton loaded Cups

80% closed bass ports

Loaded driver baffles (to add mass)

Shure 840 pads

V-Moda Cable

You can find more info on specific mods and their effects on the thread over at head-fi however these are the ones I have found to work best for me and giving sound very very close to my favorite the LCD in side by side comparison and measurements.

So what are the results of Modding the Fostex T50rp?

Fostex T50rp – Packaging – (7.5/10)

The Fostex comes in a branded cardboard box with little else other than the cable and cable jack.  Not bad but not stellar by any means.

Fostex T50rp – Looks and Build Quality – (9/10)

Personally, I think when you get the Shure 840 pads on these they are a very good-looking set of phones and are finished well headband adjustment is smooth but stays locked in tight.   They are rather large so you probably won’t want to wear them out and about, but they look and feel like a quality product.

Fostex T50rp – Isolation (8/10)

Semi-open design on these is never going to be the most isolated phone, they do leak a little noise but seeing as these are mainly for home listening to its really no problem, you can increase isolation by sealing over the vents however this drastically reduces the bass levels, I have it 80% closed so sound leakage is minimal.

Fostex T50rp – Comfort (9/10)

Stick a set of the 840 pads on and these are one extremely comfy set of cans, clamping force is just right and they are not as heavy as some of its wooden-clad morphodynamic brethren.

Fostex T50rp – Sound Quality (9.5/10)


Incredibly clear and spacious sounding 

Bass doesn’t boom from these it is controlled and of good quality, it hits as hard as it should and doesn’t overwhelm by bleeding into the higher ranges.  It has good speed in its attack and does not suffer with becoming muddy or flabby as some of its competitors do (especially compared to fashion headphones)  

Mids are strong here they don’t sit forward or anything but the way in which they are presented is very nice Rodrigo and Gabriela comes alive with these phones guitars being realistic and resonating nicely and I suspect this is due to there being quite a bit of air behind the driver even though it is closed cup.

Highs are also very good although in some cases case get just a tad too hot, for genres like rock and metal they sound great with cymbals crashing.  With Jazz, it is not the same though I found that this was the genre where you could seek out sibilance if you looked for it in certain trumpet sections.

One thing to note is that these headphones have excellent PRAT something that is often not talked about but when you hear it it is a great feature.  

On a final note, One should be reminded that the HD660 is 150ohm impedance which is getting into the higher realms.  You absolutely will need an amp to get the most out of these with possibly only the upcoming Fiio x3 or heavyweights like the Ibasso DX100 and Iriver AK100 being able to handle these out the headphone out. 


Fostex T50rp Headphones – CONCLUSION

At £30-£35 the HD-660 is a bargain, upgrade them with premium Beyer parts as the originals wear out then even more so  They aren’t going to take out +£100 Sennheisers or Beyers, etc but they get close to some in that price range.   In direct comparison with the Shure 440 (reviewed here:  I would take the HD660 any day for casual listening although for Studio use I would stick with the Shure’s.

At this price range, there are few headphones that perform so well, look so good, and have easily replaceable parts (even changing out the cable to a custom one is a 2-second job).  Anyone looking for a set of full-size circumaural under £70-£80 should definitely give thought to the Sennheiser 660.

Audiophile On
Audiophile On is a website dedicated to high-end audio products. With over 15 years as a reviewer, all articles are hand-written by one person to allow the comparison of products. Headphones, earphones, speakers, amplifiers, or DAC's we cover here.

Related Articles



Please enter your comment!
Please enter your name here

Stay Connected


Latest Articles