A Background:

Today we are not going to start with the product at hand, but a little bit about what is perhaps the world most modified headphone, the Fostex T50RP. They are probably the most modified headphones on the market and that comes down to the driver technology used in them and how much potential it has. The T50RP is the cheapest Orthodynamic headphone on the current market (since its initial release in 2002) and by a long way as well. It is priced at 100 pounds, a quarter of what you will be set back for the HiFiMAN HE-400, the least expensive of the rest. Now technology is of course not the last word but the reason why it has become one of the modded headphones is that the general consensus about the headphone, is that the driver in the headphones has a lot of potential but the dampening and tuning of the stock driver is not ideal and that’s where the modding comes in. Now with some headphones such as the Denon AH-DX000 headphones, most tweakers followed a set pattern too get a similar desired result but with the T50RP, there are a lot of different methods and paths you can choose and results can be varied (I have seen a range of modifications of T50RP measurement and some are horrific while other marvelous) depending on what you want. So where am I going with all this, well Zach Mehrbach of ZMF Headphones has decided that he will take his modification of the T50RP and share it with the world.

Along Came ZMF:

Now Zach doesn’t skimp in the slightest when it comes to modifying the T50RP and he offers up a completely custom service where you choose exactly what you want to be done and he will even give you personal advice when it comes to some of the more finer details. ZMF offer 4 tiers of modifications, with a package deal on each tier and a combination of mods that are both physical and internal (sound quality related). Now the first tier is your bread and butter mod, the ZMF Basic. The ZMF Basic mod leaves you with a headphone that will look no different to the stock headphone; it is strictly a fine-tuning of the headphones, its all going on under the hood and boy do ZMF know how to tune a headphone. Now what’s pretty incredible is that this mod is just $199, so yeh, like 20 pounds more than stock and for another $30 you can get the package deal where you also have HM5 pads included, they sound great and are so much more comfortable that what the stock are and their leather headband, which I have not tried. Go up a tier to the ZMF Re-Jack  ($249, $280 Package) and the modification is once again sound quality based. With a stock pair of T50RP you have a 3.5mm jack for the removable cable but, it does not seem to be of the best quality so you can have that either replaced with a gold plated 3.5mm jack or a 4 pin mini XLR (allowing to balance the headphones, much better option in the long run). In the package deal you get an upgraded Canare cable and for aesthetics, you can get a carbon panel on the housing of the headphone, removing the stock look. The next two tiers are where you can pretty much let your imagination run wild and get something is VERY personal to you. Tier 3 is ZMF Painted that allows you too have them airbrushed too your choice of colour, whatever you could fancy and they also do a mean powder coating on the headband sliders, price can vary here depending on what you go for here but it could be between $289 and $379, this mod is aesthetic based only. The last option is for those who want the best, both aesthetically and sonically because you get one last upgrade for how these will sound, welcome to the ZMF ZPEX Master Model. They replace the stock cable between the re-jack and the driver too a boutique cable, with offerings as luxury as ALO Audios Cryo wire and Cardas Golden Ration Copper. The Master Model works as a package deal and you get everything included that I have mentioned including the Pilot Pad (headband strap what is used in Aviation) and an amazing storage hardcase from Seahorse. The Master Model is $399 for one with carbon panels and up from $469 if you want painted, depending on what colour you fancy.

Mogami Cable – Single Ended

Canare Cable – Balanced RSA/ALO

Military Spec Silver Plated Copper – Single Ended

So of all of them options what I have got too review? Well I have two, completely pimped out Master Models. Now there is actually a very fair explanation to why I have two and it is not just because I am greedy (although I can’t deny the accusation). All the way from the Tier 1 ZMF Basic, depending on your music tastes and what your after in a headphone, there are two tunings to pick from, the V1 “Classic” and the V2 “Bass” and I have one with each. ZMF first designed the V1 (through around 20 iterations) and the reference for this model, was the HiFiMAN HE-500, trying to if possible design a closed back version and if your familiar with the HiFiMAN, you will know it is a very balanced sound with a tight, honest bass. Now the V2 is not made to be a bassy headphone but instead is meant to have a just a bit more punch and life in the bass, more ideal for quieter listening, noisier situations or generally if you like a bit more warmth. The sound of these headphones is still rather personal to each individual pair because of the amount of options, without including the effects of cables, there are 8 different combinations of sound you can go after with both 4 ZPEX internal cable options on both the V1 and V2, obviously they are not going to be huge difference from one to another but more just adjustments in the sound. Here is what I went for:

ZMF V1                                                                                   ZMF V2

ZPEX – Cardas “Golden Ratio” Copper                          ZPEX – ALO Cryo SPC

XLR Re-Jack                                                                     XLR Re-Jack

Painted Cups – Metallic Burgundy                         Painted Cups – White

Powder Coated Sliders – Burnt Copper                 Powder Coated Sliders – Black

Pilot Pad and HM5 Pads                                               Pilot Pad and HM5 Pads

Canare Cable with balanced Kobiconn connector     Mogami Cable

                                                                                                  Military Grade SPC Cable

The options are so expansive and it really does allow to personalize the headphones in all ways and the website is a great companion to making your choice because Zach goes great lengths to describe the options as thoroughly as possible and make your choice as easy as possible. Enough of this though and lets get hands on with the headphones.

My V1s

My V2s

Are They Tough?

These headphones are still very much T50RPs but everything that matters is significantly upgraded. That means that the overall build quality, doesn’t deter too far from what you get with the T50RP. The headband is a flexible silicone like plastic that if you was to really test, would likely laugh of the abuse and this is further protected by the thick, chunky Pilot Pad that is locked with Velcro around the headband and can be removed if you wish. The headband sliders are metal and are the least of my worries and the powder coating is flawlessly finished and has a real nice touch but I do feel like one pair is harder to adjust than the other. The cups are plastic and while they don’t feel the thickest, I don’t see how they could get damaged unless you drop your headphones a lot. The paint job is very clean and well distributed on the cups and it has protective layers to prevent wear and scratches. It does have a slightly DIY feel with a bit of paint going over the rim of the cups next to the pads but only detectable on a close inspection. The introduction of the mini XLR connector is great and not only because it allows the headphones to be balanced but because it is generally a more sturdy and secure connection than a 3.5mm jack. The jack locks in and has a clasp to release and the whole thing is a pretty satisfying experience. The mini XLR is however not completely flush with the headphones and the paint seems to have cracked a little around the connection. A black o-ring has been placed around the jack and this neatens things up but this is the only other DIY imperfection I have noticed and again, is only detectable on closer inspection. Cable quality really depends on what option your spring for. As of now you can get a Canare, Mogami and Military Silver Plated Copper cable but ZMF are going to launch some braided cables soon. I have all three of the current cable options and will say that the Canare and Mogami are very similar, they are chunky, smooth feeling, malleable while not having the biggest range of movement and really are strong, and I really like both these cables. The Silver Plated Copper cable is sleeved so actually feels stronger but the sleeve allows very little movement and the cable is very stiff. They cable also has a small microphonics problem, if you scratch the sleeve you can hear it in your ear and the same applies for if you knock it, which for portable use could be a turn off. I find this cable fairly annoying if I am honest.

ZMF Sticker would look good replaced by an engraving but check out them sliders!

The Mini XLR Connector

Seahorse Case To Keep them Safe!

Lets Put Them On:

Right now, out of all the many headphones in my collection, I would have to say these are the most comfortable; they are like a cozy warm bed for your head. I wouldn’t say that they are that light but the chunky pilot pad has a large surface area and distributes the weight really well so the feel pretty light on your head and my neck never gets sore. The pilot pad is also extremely soft and doesn’t cause any stress on your head. On your ears they adjust perfectly with the sliders getting the cushions lined up and the cups having some articulation on the yoke to get the right angle. As for the pads, well just go and look up my Brainwavs HM5 review because they are one darn amazing pad, so cushiony, soft and enveloping. These are how comfortable headphones are meant to be and I can recommend these easily simply for someone looking for a comfortable headphone.

Isolation is pretty run of the mill as far as circumaural headphones go; it’s not a problem or something where these excel. As far as I am concerned these headphones are completely portable, they get rid of the bulk of external noises you will come across while out, traffic, chitter chatter, the usual pretty well and allow you too enjoy your music.

I have just realized I have not yet talked about the look of these and I love them, I think they have a real retro sense too them and that with the combination of paint and sliders I have, leaves these looking both unique and pretty darn neat. Do you dig the Carbon Fibre look? Well then there’s an option for that! Do you dig something that’s understated? Well then why not go for a stealth black finish. I don’t think you can beat personalization and with these, you really are catered for.


Buckle up guys because we’re finally plugging these in and going for a listen. Annoyingly I wont be offering comparisons to any other T50RPs as the only other variation of the T50RP I have heard is the Mad Dog (not sure which version) when I was on holiday in the states so these T50RPs are a brand new sound experience and I really mean that because I have not heard a closed, portable headphones that sounds like these. Having a deep, dynamic and smooth sound could summarize the Classic, the original, the V1, and the sound signature is just so amiable. We start with a bass that really is top notch, listening to Fleas entry bass riff on ‘Ethiopia’ by the Red Hot Chili Peppers seems to have just the right amount of decay matched with a great depth and extension. The bass is intoxicating because it is the type of bass I really dig, something that has a very real timbre, has a visceral, rumbling texture in the sub-bass and then somehow both the sub and mid bass is pretty linear with the midrange. Now don’t get what I’m saying confused with measurement linearity between the bass and midrange were in reality it is a more bass light sound because the bass here really is full sounding and the impact is pretty strong. Now Zach used the HE-500 as a reference and I have to say you get a slight bit of extra mid-bass with the V1 but they have better extension and they have a better rattle of the real low stuff. The overall way the bass has been constructed is just clever, the characteristics compliment each other, the brilliant extension does not shadow the mid-bass and in the same way the when called for hard hitting mid-bass does not get carried away or leave the sub-bass getting lost.

 The transition into the midrange is very coherent and effortless; in all honesty this headphone is generally very coherent throughout the frequency ranges and this what leads to the über smooth sound. The midrange has presence that puts everything there right into the mix, its borderline being forward and everything has great height and positioning. Dynamics and macro details are where I find the midrange to really excel. When things explode, man these headphones let you know and when you have something delicate like a flute it captures the small, angelic nuances just spot on. A follow on from this is that the timbre is just fabulous, decay always seems to be spot on and the way instruments impact is just rich and textured. If some percussion is playing you can pretty much make a conclusion of what is being hit, the make up of and I’m pretty sure I could have a good guess at the colour. Male vocals have just a hint of warmth to them, nothing major and they are also thick, like the HE-500 in that regard although they don’t quite pick the more minute details like they do. The midrange has some weight too it in general but it is still very clear. The upper mids are balanced with the rest and it does not have an extended feeling of clarity to it, just a natural clearness that is nice. It is never sibilant in this region and it remains nice and smooth with a real tone to female vocals that have a little bit of sweetness to them although not on the same level as the HE-500. My biggest regret with the midrange is the micro details and overall transparency is just a little bit lacking.

Moving past the midrange and into the treble things seems to get a little more relaxed. These headphones are still pretty balanced and I would not say they are dark but the treble is the most subdued frequency range on the headphones. This being said everything going on in these registers is obvious and audible. I can’t say it is the most detailed treble in the world but it has that buttery vibe and the weighty timbre that this headphone does so well. I guess when you get a bit further the extension is just a little bit rolled off because these don’t sound that airy even though they are a spacious headphone. At 10khz were the sparkle sits I do sense a little boost in the range that allows high hats to have a clear impact but it is not huge or other the rest of the music and remains un-fatiguing.

Now you know me enough that one of the first tick boxes for me when I test a new closed headphone is that the soundstage is not projected between my two ears and these do a fantastic job. They don’t have the incredibly airy and extremely wide soundstage of the Beyerdynamic T5p but they have an overall three dimensional image that is cohesive and has good focus. It scopes quickly with left to right imaging while whatever is happening in the center image is controlled. Height seems good and I do find depth to be evident but it is not revolutionary, the overall make up though leads to a headphone experience that has more in common with an open model than a closed one. Imaging is also very confident, booting up “Money” by Pink Floyd and you have the reoccurring cashiers happening in their own black space to the left and right of your head and then in a more forward position in a narrower field you have the instruments and in the dead center you have the vocals. Everything can be individually and obviously recognized and it works with the layers well.

Now as I mentioned earlier these are not the most transparent on details, even though I do find them tight and fast enough headphone. Now for those detail freaks this may not be ideal and too be fair I have always thought myself one of them, nothing can beat the completely revealing nature of my T5p or the HD800 for some listening. That being said they are both headphones (among others) that you feed them some files and they will happily chew them up and spit them back out right in your face. Now these headphones manage to make me smile with pretty much everything I listen to, they have a magical property to just put a cozy layer over the not so well mastered tracks and leave you to enjoy them. When I received through my modified AK120 it had some tracks preloaded for QC testing and those included the 2013 Billboard Top 100 songs, the annoying pop stuff I can’t stand when my sister plays it on the radio. However I gave these a listen and I was a little bit shocked and a little bit ashamed because I actually enjoyed a few songs I never though I would. These are headphones that have been able to cater to any genre I have thrown at them and I am talking some heavier stuff like Bring Me the Horizon all the way to Miles Davis to some sample classical tracks I have in DSD.

The V1 is a straight up marvelous headphone and one that I can recommend with relative ease but like with everything Zach knows from some first hand experience that no headphone is for everyone and that is what lead him to designing a second model with a tuning that was just a little difference. ZMF calls it’s the V2 “Bass” but the idea was never for it too be a complete redesign, just a headphone that does things a little differently. Now the differences are obvious enough but the headphones do clearly share a DNA.

The V2 bass is what I would describe as a warm headphone that is coupled with a sweet midrange. We do now have a slightly boosted bass that starts of moderately in the mid-bass and it incrementally gets a bit stronger as we get into the deeper regions. The bass has just a tad of extra decay, which leads to a little bit of warmth and a slightly larger hitting body. The sub bass is now a real force to be reckoned with, packing some incredible power and a real rumble.

The midrange is still right on the front line of things but it seems to now have a slight tilt to the higher midrange, maybe from the slightly boosted mid-bass. It has a better sense of clarity and a slightly lighter feel. The lower mids do feel a little less present and also sound just a little bit less natural. Due to the higher midrange having a bit more zip though the overall midrange does feel more detailed and also a little airier and no need to worry, we still lack any sibilance. In qualities the treble is very similar but I do find the V2 too have just a little bit more kick to it and these headphones are just a bit brighter with a little bit more sparkle at 10khz. Still I will say they are not fatiguing and smooth and I would not complain with a bit more extension and air.

Something I was quite surprised about was that I feel the V1s did have the wider more expansive soundstage by a touch, not something I was expecting. I also find the presentations of soundstages on both models is pretty close to the stage but the V2 seems, perhaps a row closer to the music so it is a little bit more forward and with you.

Like the V1 the V2 is very healthy with a lot of music but the extra bass slam does let it get on just a bit more with music such as pop, EDM, trance and hip hop but it still has impressed me thoroughly with a lot of music. The extra bass does do a job of helping it block ambient noise a bit more on the go and it also allows a better low listening experience so if these are things that are important then the V2 could be the way to go. I do find the V1 is the more versatile headphone but if you’re into more specific genres where bass is very important then the V2 also has its perks. That being said I really do mean it when I say it can do an impressive job still with most genres.

So What’s Been Driving Me Crazy:

Its no secret that orthodynamic headphones are not easy to drive due to very low efficiency and the 50 ohms impedance of these headphones is misleading. With these they can be made loud fairly easily but using a range of my gear I have discovered these really do have a great ability to upscale into something incredible. As I have put these through quite a few different sources from portable to desktop and single ended to fully balanced, I thought it makes sense to walk through my different findings. I will be sticking to use just the V1 for this.

iPhone 4: This just your standard iPhone 4, nothing special about it and it is the phone I use on a daily basis. As it is not something I use for listening to music other than the odd time like this or at parties, music is mainly MP3 and a combination of 256kpbs and 320kpbs, no lossless, no high resolution here. Starting up the music I got to about 75% of the volume bar to get a comfortable listening volume and 100%, which I didn’t even get up too would certainly be unbearable. I guess these are not as inefficient as the likes of a HE-500 as that has a lower sensitivity and takes a lot more volume off of my iPhone 4 to get happy but as I have already stated, volume is just one variable. So volumes not so much of a problem, but the sound is the more important one and right off the bat they are clearly still good headphones, they just aren’t what they could be. They maintain the general sound signature I described but things are just a little different. Starting with the bass it just doesn’t quite have the extension that I have got out of it, it is still extended but it just doesn’t have the same feel, the same body, and the same throb. The mid-bass is a little looser and generally things just are not as detailed, big, bold or powerful through out rest of the frequency ranges. We lose a bit of the magic from those big dynamics the headphones are capable of and the headphones are not as snappy throughout. The sound is also noticeably thinner and the soundstage is less expansive. While all in all they completely listenable from the iPhone, I have too be honest and say that I do find myself missing quite a bit of what the headphones can offer with some of the other stuff I have and honestly I think if your using something similar to or an iPhone 4, I think your missing out on what you can get out of this headphone. Technical Level – 25%

Mezzo Soprano MS-AK100 (AK100 with 22ohm output resistor bypassed): Now we are moving up from you everyday do it all device to something that has audio as its only target. We have high-resolution capabilities on it and all music is Lossless FLAC at the least all the way up to some hi-res 24/192 files. Even though it is a dedicated music player, it is not the most powerful and that is something that is quite apparent here. Too be fair the difference between this and the iPhone is not as big as one may expect. This is mainly due to what I feel is an under powering and we get the same small soundstage, weak feeling sub-bass and a generally thin sound that feels like it needs some life thrown into it. I guess overall we get a little more detailing here than with the iPhone 4 but I still think we are a little way off what we can get too. Technical Level –  35%

Smallish Portable Rig – MS-AK100 Amped w/ Leckerton UHA-760: The UHA-760s low profile allows you too add an amp too the AK100 without too much bulk. The Leckerton is not my most powerful portable amp I could have chose to use by a long shot and it seems to perform at its best with IEMs but I know when you come to my reference portable rig, it will be a bit too bulky for some people so this is a rig that I think most people can still accept as portable. I powered the Leckerton up with the high gain setting and for the first time, we feel a bit of life being breathed into the headphones. The dynamics improve, that sub-bass becomes that much more potent and we have a much better sense of space. The Leckerton actually brings out some of the best treble I have heard on the headphones; it is very clear and just a bit brighter but still controlled. The sound is however still a bit brittle and timbre isn’t as rich as it can be. This sort of portable rig is certainly pushing the ZMFs to better things and this is the sort of set up that someone could be very happy with. If your happy with an amp that is just a little bigger then the VicJohn Audio Lzio HAV3 done an even better job with its balanced output and the Tube Amp TA-1 was one of the more airy combinations with these! Obviously the AK100 is just were my music is but a similar source such as a DX50 or even a iPod Classic with a dedicated amp should give you a performance in the same ballpark. Technical Level – 70%

Desktop Rig – Audirvana Plus through USB to BMC PureDAC Balanced Line Out too Questyle CMA800R: This is my daily used desktop set up from iMac. Music is of course all lossless CD ripped FLAC, hi-res and now some DSD. This synergizes with the ZMFs like nothing else in my collection. The tonal balance is unrivalled and the timbre is so real it is breath taking. The sound has a lot more bodied and is much thicker now and the sub-bass is simply insane. Everything is tight, under controlled and coherent and it really is an eye opener were you can take these headphones. On a pure technical level this is the best I have heard them and they both sound a lot better than their price tag makes out. The difference between this sound and the previous rigs is quite substantial. Technical Level – 100%

Reference Portable Rig – PWAK-120B Amped w/ ALO RX MK3-B: Being able to make them sing on a completely stationary set up is of course great but you do want to be able to replicate that as close as possible while on the go. This rig is a project of mine that starts off with the ultimate modification for the AK120 and that is replacing the DAC with a Wolfson WM8741 and giving it a balanced line out (modification is done by Peter Wong in Hong Kong and he does it for a price that is nothing short of a bargain). I then use the balanced line out to the balanced ALO amp and use the included balanced cable so this rig is completely balanced.  What is amazing is that this can do things that the desktop rig can’t, the focus is better, the background even more black and the soundstage is a little wider and deeper. The bass extension is not quite what the desktop rig is but the midrange feels more detailed and the treble has some more air and sparkle. The sound is still meaty and everything is pretty similar to the desktop rig. The sound is actually more balanced and while I would say that technically this rig is 2% behind, I actually enjoy the synergy more. If you can pair it with something of this sort of level on the go then you really will be in for a treat, the sound is just phenomenal and the ALO amp seems to really get on with the ZMFs as it is a very powerful portable amp. Technical Level – 98%

Wrap Up:

I am pretty sure I don’t have to say much more for you work out that these headphones have made grin ear to ear. For the first time since the T5p I am enjoying using a closed headphone so much that I use at home almost as much as my HE-500. These headphones are straight up musical and they really do let you enjoy music to the max and that is not something that I can say about a lot of products. The V1 was more my cup of tea and the one that I do find myself listening to most at home but on the go I do like to grab the V2 and the same applies if I ever watch a movie on my computer because the extra oomph is just what I am after. Just for the added weight I will be purchasing the V2 as only one of the units was a free review sample and I really don’t see a reason why I wouldn’t want to own them both. Zach, you have done something marvelous and here at Inearspace we can’t wait too see what you bring in the future, a future that is already looking very bright with the upcoming ZMF x Vibro Wooden housed T50RP!

Sonny Trigg