Fostex T50RP mk III Modded Build - New Cups, Cable, the works!

If you've been following my posts you'll see I usually leave audio products alone once I get them ... kidding ;) I picked up a Fostex T50RP mk3 (or mk III, however you want to write it) so I could see the differences from the original T50RP I modded. Other than a different headband, removeable cable, and different handling of the felt behind the driver, there was no difference, so I suggest if you are already modding, go with the original as it's cheaper and you can set up the felt however you like. If you still want the mk3, You may consider purchasing across the pond, it seems like Fostex has a deal with U.S. retailers that they can't advertise below $159.99, but it averages around $130 in the UK... much more palatable as you're replacing everything anyway.

The headband is worlds better than the original model

The removable cable was a nice new feature on the mk III

I had some very nice wood cups CNC cut for me by my friend Fewzi (if you'd like his contact information, shoot me a message, we're hoping to offer at Zynsonix soon), the quality of the machining is excellent, perfect driver fit. CNC machining has really changed the way a lot of things are manufactured in a positive way, the amount of precision it offers is outstanding. Anyway, the wood cups rock. There is the cup itself, a second wood layer with a square hole that holds the driver in place, and a third plastic layer that holds the ear pads in place.

Driver frame and wood cup, ultimate precision

This picture below shows a wood ring and plastic ring for the earpads, Fewzi discovered that plastic was more durable for the earpads to stretch over (it's a tight fit). 

First the stock pads and foam are removed.

Then the driver frame is unscrewed (4 screws), and the driver unscrewed from the frame (3 screws). There is an extremely thin gasket that sandwiches between the driver and frame that needs to be handled gently. 

The drivers are snipped free and then I had to remember how to get the cups off. I didn't want to read my existing post because I enjoy discovering how things come apart and go back together. Fostex hides the screw behind a thin shroud of plastic, which I believe is sonically welded in place (micro-vibrations that fuse plastic together). It comes off with a razor, and once unscrewed, releases the clamp on the other side.

That's about the only unusual aspect of the assembly. Once everything is apart, the wood cup was fitted. There are little brass fittings included with the wood cup (the original plastic ones are too small) that allow the cup to pivot when screwed in, I found the sizing of the brass fitting and tightness of the screw makes a huge difference in the articulation. 

If anyone has heard a T50RP,  modified or otherwise, they know there is no lacking in the bass department. this is where mass damping plays an interesting part. Adding loaded sheets like Dynamat Xtreme can help curtail flabby bass and tighten things up. Adding foam with a texture can also assist with reducing reverberation / standing waves in the cup. 

The cups included 3.5mm mini inlets, which are great, but I personally like the mini XLR for headphones due to it's locking mechanism, and I could configure it the same as Audeze headphones, which you can read more about here. The driver is fastened on to the wood frame, which was a fantastic fit, with the gasket in place. Wiring up is a simple ordeal, but I wanted to ensure all the original solder was removed so I could replace the tin solder with Cardas Quadeutectic solder. The tabs are marked with a "+" and "-". Below you have a view of both sides being soldered in. 

Once the drivers are happy, the frame is lined up on the cup and it's important to ensure no stress is on the solder pads, so loose wiring is okay here. Then the earpad frames are sat on top and four screws replaced. The foam that was set aside in the first step is replaced in each cup. 

This could be no exciting rebuild without fancy pads. Fortunately there are a couple different types available from ZMF (run by Zack, cool bro), and MrSpeakers. ZMF has a number of pads available, including lambskin, cowhide, protein, and Omni. MrSpeakers offers the Alphapads which are lambskin. Lambskin seems to be the most popular headphone pad material for higher end headphones, for which I am glad, I hate velvet ;) ZMF also has a nice "pilot pad" to provide some extra cushion on the top of your head.

ZMF lambskin earpads and pilot pad

Now that we're all padded up, we have what appears to be a finished headphone, but wait...

...where's the cable you ask?! We won't have any sound if we don't have a cable. Where will we get a cable from?

Fortunately, we have the brand new Zynsonix Ballista cable here, featuring 28 strands of ultra pure ohno cast copper, 12 of which are clad with high purity silver in an alternating geometry, then each are electrically isolated with a clear coat, fed through low loss dielectric, resulting in an extremely well balanced sound with great detail retrieval... completely custom made for Zynsonix. 

There we go, now we're talking! 

I'm now going to reveal a special secret that will enhance your life forever make your cans sound better... you can get the Zynsonix Ballista configured for pretty much any headphone you have. It's the best cable I've made to date, I spared no expense, because you guys deserve it. Use the handy dandy contact link to share what you need. Also if you are interested in purchasing some great sounding cups, feel free to reach out as well. Fewzi is experimenting with some additional woods now, so there should be a variety of species to choose from. 

Anyway, that's all from me. Happy listening, building, etc. and don't be a stranger.

Disclaimer: The above steps detailing the building of a headphone are for entertainment purposes only and not intended to be used as directions. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted and cause physical harm to yourself, your surroundings or your property.

Headphone Connectors & Pins / Pinouts for DIY

So, as you have probably noticed, headphone manufacturers are not very good about standardizing connectors for use with headphones and amplifiers, to the point of absurdity. I am going to try and document most of the different headphone connector pin diagrams aka pinouts in one place so you don't have to pull out your hair tracking them down. If you need a cable built with any of the connectors below, reach out to Zynsonix Audio.

The 2.5mm TS with narrow shoulders originally was created for use with the Sennheiser HD700 headphone cups, but now has also been adopted for the Oppo PM-1, Oppo PM-2 and can potentially be used with the HiFiMan 400S, HE-560, HE-1000 and Edition X as the stock TRS does not use the ring (R). The tip is used for signal/positive, and the sleeve is ground/negative.

Recommendations: The best I've found are unbranded/generic connectors with the gold plated connector, chrome barrel and "long shoulders" which looks like the illustration above. I don't advise the other plastic/nickel plated plugs.

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The 2.5mm TRS is found on some mobile phones, although most use the ubiquitous 3.5mm TRS. The tip is left signal (L), the ring is right signal (R), and the sleeve is ground (G).

HiFiMan headphones (New Models): includes the updated HE400S and HE560, HE1000 and Edition X, which use this connector at the cups. Per measurements, the tip is the positive, the sleeve is the negative, and the ring doesn't appear to be used. 

Recommendations: As of right now, the best 2.5mm TRRS is made by Furutech, the FT-7254(R), but you'll pay for it at $35 a pop. Otherwise, Aliexpress is a good source if you purchase from a reputable vendor, and you can get fancy with carbon-fiber barrels, etc.

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The 2.5mm TRRS is commonly used for balanced operation for Astell and Kern portable digital audio players. Tip is right negative (R-), ring closest to tip is right positive (R+), ring closest to sleeve is left positive (L+) and sleeve is left negative (L-).

Other applications: 
Onkyo portable DP X1 DAC:  Tip is right negative (R-), ring closest to tip is right positive (R+), ring closest to sleeve is left positive (L+) and sleeve is left negative (L-).  : Source

Recommendations: 

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The HiFiMan HM-801 digital media player and Oppo PM-3 headphone (balanced) follow this unique configuration using the 2.5mm TRRS. Tip is left positive (+), ring closest to tip is right positive (+), ring closest to sleeve is left negative (L-) and sleeve is right negative (R-). Get yourself a nice aftermarket cable using the TRRS from Zynsonix Audio. 

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The 3.5mm connector (aka mini connector) is the most ubiquitous plug used for portable audio. The tip is left signal (L), the ring is right signal (R), and the sleeve is ground (G).

HiFiMan is now using 3.5mm plugs for some of their headphones as well like the HE-560 v3 just to keep us all on our toes. I have not tested a stock cable for the 560 v3, but using the tip for positive and connecting the ring and ground to negative works perfectly well. They're probably not using the ring like previous designs. 

Recommendations: There are tons of great options out there from Switchcraft, Canare, Oyaide, ViaBlue, Amphenol and more:

Amphenol K Series: Great value and there is an extended shaft version for use with phone cases.
Canare F12: Perfect if you are using thick cable thanks to the large barrel, but a bit heavy and may not fit some devices due to size.
Furutech FT-735 (R): I personally avoid this rhodium plated 3.5mm, the ground sleeve does not accept solder even at high temperatures in my experience and I had one where the tip broke off.
Neutrik REAN NYS231: Very slightly smaller than the Switchcraft, not as well made in my humble opinion, but low cost and works. If you have the scratch step up to the Amphenol K Series.
Oyaide: A bit overpriced in my opinion, but the long shaft version is one of the only connectors I know of that can fit Ultrasone headphones.
Switchcraft 35 HD series: A rugged, U.S. made plug, medium-sized and easy to use. The right angle version is very solid. If you order a ton of the right angle versions, be sure to test them before use... in rare cases you can run into a dud (in my experience).
ViaBlue T6s: If you're looking for audio jewelry, this will scratch your itch. The strain-relief system is a little awkward with set-screws and different-sized plastic rings, otherwise relatively easy to use. There are two sizes, small and regular. 

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The 3.5mm TRRS has quite a few applications:

iPhone and many other mobile phones: The tip is left signal (L), the ring closest to the tip is right signal (R), the ring closest to the sleeve is ground (G), and the sleeve is the microphone connection.

Oppo PM-3 headphones: This is used for the balanced cup connection for the Oppo PM-3. Per Oppo, the tip is L+, the ring closest to the tip is R+, the ring closest to the sleeve is L- and the sleeve is R-

Hifiman HM-901: Tip is L+, the ring closest to the tip is R+, the ring closest to the sleeve is L- and the sleeve is R-

Geek Out V2: Tip is L+, the ring closest to the tip is R+, the ring closest to the sleeve is L- and the sleeve is R-

Custom Red Wine Audio can feature this jack: RWAK240, RWAK380 and MZAK240

JH JH3A digital connection - Tip is left (L), ring closest to tip is right (R), the second ring handles digital coaxial information, and the sleeve is ground for both analog and digital.

For DIY Audio Parts, check out

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Leave it to Sony to come up with some weird format that confuses the market further ;) #Beta. To be honest I actually kinda like this connector. It's easier to work with than the teensy-tiny 2.5mm TRRS and less likely to break off in a jack due to the added girth. I still think the ideal connector should be locking with pins like a mini XLR versus spring tension like with this TRRRS, but since this is likely only going to be used with higher-end DAPs, the females have been of high quality so far and don't seem predisposed to failing over time.

I haven't seen the ground sleeve being used for anything yet, but from the tip, the connections are left signal positive (L+), left signal negative (L-), right signal positive (R+) and right signal negative (R-).

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The 1/4" TRS (aka 6.25mm TRS for the metric folks) is the most ubiquitous plug for home/studio headphones. The tip is left signal (L), the ring is right signal (R), and the sleeve is ground (G).

Recommendations: I find the Neutrik NP3C-BAG to be a great value 1/4" connector and the Furutech FP-704 (G) to be a great choice if you want to spend a few more dollars.  

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The mini XLR has become quite popular in the headphone market as it is relatively small, it locks in place, and the connections are more reliable than your average TRS. The mini XLR 3 pin is commonly used by AKG for their K-240S, K271 MKII, K701, K702. K712 and other K701 derivatives like the Quincy Jones Q701. The pins are labeled on nearly all mini XLR connectors, though you may have to look under a light to see them.

For the standard AKG wiring, pin 1 is ground, pin 2 is right signal and pin 3 is left signal. 

Recommendations: The tried and true is the Switchcraft TA-3, however I prefer the REAN RT3FC and RTCMC models at the same price as they seem a little more sturdy and have two different strain relief sizes depending on your wire size. The Furutech FT-610 resembles the Switchcraft, however has nicer rhodium plated connectors and looks a little prettier. Bottom line, if you want the best available, go with the Furutech, and if you need the best value, go with the REAN. 

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The standard-sized XLR is used for a few different applications. As an audio interconnect, Pin 1 is the ground, Pin 2 is the positive signal, and Pin 3 is the negative signal. You'll notice that most XLRs have the pins labeled 1, 2 and 3 if you look closely enough.

Recommendations: The Neutrik XX series is a great value. I also like the solid weight and feel of the Switchcraft AAA series, and they're two piece, so a little easier to assemble. If you'd like super solid and have a couple more bucks to spare, the Furutech FP series is a nice choice.

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Headroom initially debuted their first balanced headphone amplifier in a dual 3 pin configuration (I suppose if someone wanted to have headphone monoblocks in the future), however the 4 pin XLR proved to make more sense as it's an easier, less cumbersome implementation. You'll notice that most XLRs have the pins labeled if you look closely enough. Pin 1 is L+ (left positive), Pin 2 is L- (left negative), Pin 3 is R+ (right positive), Pin 4 is R- (right negative). Nearly all balanced headphone amps use this configuration, as well as the legendary AKG K1000. 

Recommendations: The same recommendations from the 3 pin XLRs are echoed here: Neutrik XX series is a great value. I also like the solid weight and feel of the Switchcraft AAA series, and they're two piece, so a little easier to assemble. Furutech also just released (FINALLY!) a 4 pin XLR, the FP-705 in 2016, which is a great choice for a few more dollars. 

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As mentioned above, Headroom initially debuted their first balanced headphone amplifier in a dual 3 pin configuration. It still sticks around today, however is not as popular as the 4 pin configuration. You'll notice that most XLRs have the pins labeled if you look closely enough. Pin 1 (typically the ground) is not used for balanced headphones. Pin 2 is used for the positive signal, and pin 3 is the negative signal. In this diagram, the white wire is left positive (+), the orange wire is left negative (-), the red wire is right positive (+), and the blue wire is right negative (-). 

Recommendations: The same recommendations from the 3 pin XLRs are echoed here: Neutrik XX series is a great value. I also like the solid weight and feel of the Switchcraft AAA series, and they're two piece, so a little easier to assemble.  If you'd like super solid and have a couple more bucks to spare, the Furutech FP series is a nice choice. Also the Cardas CG series is pure eye candy and a popular choice of my clients.

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The Kobiconn Auto IRIS is an odd little connector typically used with cameras. These are found on Ray Samuels (RSA) balanced portable headphone amplifiers like the Protector and SR-71B, however are also on amplifiers Centrance GloveAudio A1, HiFi M8, and the ALO Rx Mk3 B. Pin 1 is left positive (L+), pin 2 is right positive (R+), pin 3 is left negative (L-), and pin 4 is right negative (R-).

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The Male SMC connector is used to connect to older HiFiMan headphone cups, and current models such as the HE-6. As you can see from the pinout, the signal is the small center pin, and the ground is the textured area at the end of the connector. Care should be used when soldering the ground, as using too much solder will prevent the brass cover from sliding over.

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The Sennheiser HD connector features two pins. It's difficult to notice on a quick glance, but one is larger than the other. The larger pin should be used for ground/negative, and the smaller pin is signal/positive.

Recommendations: There are only a couple of DIY connectors out there that are compatible with the Sennheiser HD265, HD525, HD535, HD545, HD565, HD565 II, HD580, HD600 and the HD650. ... Cardas and Furutech, the Cardas HPSC and Furutech  FT-2PS.

The Cardas HPSC is reasonably priced ($~16 as of this writing), but not ideal for beginners. It's a flexible molded plastic with not much room for the wire to be soldered to the internal pins, and the rhodium needs to be heated enough so the solder takes, but not enough for the plug to melt. Flux can be helpful for this, and I personally fill the cavity with a plastic-like hardening adhesive for longevity. The Furutech FT-2PS runs quite a bit more (~$46 as of this writing, but makes the soldering much easier by separating the pins with plastic, features an internal clamp for strain relief, is made of tough plastic, and looks great. So personally, I would purchase the Furutech unless cost is an issue.

This is a work in progress and there are still a few connectors to add ;) 

The Fine Print: This page is for entertainment purposes only and is not intended to substitute or supercede what a manufacturer states or recommends for their product. Zynsonix Audio, LLC does not furnish any guarantee for the accuracy of information herein, and does not assume responsibility for damages sustained by entities referencing this information for any reason. 

Zynsonix guarantees all cable and headphone work performed by Zynsonix Audio, LLC to be correct, however does not guarantee the work of other entities, whether individuals or businesses, that make use of this information. 

Pono Player Balanced Interconnect Cable

So you've taken the plunge on Neil Young's sweet little Pono player, however it uses a unique way to export those tunes to your balanced headphones or balanced rig. I'll be covering how I built an unbalanced cable, and how to build a balanced pair of cables so you can extract every juicy detail from those Hi Res tracks. As you may know, Zynsonix Audio offers these in any length or configuration, so reach out if you need one.

The Pono player features dual stereo 3.5mm outputs. You can use these to output to a pair of balanced headphones, a balanced rig that uses 3 pin XLRs (or mini XLRs / TRS plugs), or a single ended rig that takes good-old-fashioned RCAs.

Neil Young's Pono Player

Stereo 3.5mm connectors have three connections, the sleeve, the ring and the tip. When used in typical applications, the sleeve is a shared ground, the ring is the right signal, and the tip is the left signal. However not the case with the Pono in balanced mode.

Tip, Ring and Sleeve on a 3.5mm mini connector

In the case of the Pono player in balanced mode, each of the two 3.5mm goes to an individual three pin XLR. The Sleeve, as you'll note below, connects to the Pin 1 (ground). The Ring connects to Pin 3 (negative). The Tip connects to Pin 2 (positive). For a balanced headphone cable, you will note that the Sleeve connection is not used, only the tip (positive) and the ring (negative). These schematics are straight from the engineers over at Ayre Acoustics. If I'm not mistaken, this is going to be the portable standard for balanced connections including on upcoming models from Sony.

Pono Player wiring pinout / diagram

I made a handy dandy visual for the back of an XLR connector (note mini XLRs are different!) so you can see the pin assignments.

XLR pinout for reference

Below you'll see the pair of 3.5mm stereo mini to XLR cables using the great sounding Zynsonix Trebuchet 99.99997% pure ohno cast copper. The Viablue XLRs are very sleek looking, well made and use set screws rather than a traditional boot or crimp sleeve. The Amphenol mini connectors are my new favorite value connector, they offer a great connection and a recessed area near the barrel that allow them to be used with phone cases and portable DAPs with cramped faceplates.   

Pono balanced interconnect cable

All done and we have a pretty pair of Trebuchet interconnects for your Pono player. Off they go to a happy customer.

I hope you enjoyed this post on building a pair of interconnects for a Pono Player. Please reach out to Zynsonix Audio if you'd like your own custom Pono interconnects (balanced or single ended) or headphone cable, and keep enjoying those high res tracks!

The Fine Print:

The above steps detailing the build of a Pono player cable are for entertainment purposes only, and not intended to be used as assembly instructions. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted and cause physical harm to yourself, your surroundings or your property. 

Sennheiser HD800 Trebuchet Headphone Cable

Your life may change when you pull the trigger on a pair of headphones north of a grand. Your friends may decide that you've lost it, your significant other may give you a serious talk about family budgeting (or decide that the time is ripe to get that Louis Vuitton bag she's been wanting), and your daily consumption of ramen noodles will undoubtedly increase, but you'll quickly discover that there is some really impressive sound to be had in this neck of the woods.

The Sennheiser HD800 hit the streets in 2009 with a fancy 56mm high definition ring transducer that's said to produce a transmission range of 6-52,000 Hz, so even your dog would appreciate them. Lame jokes aside, the HD800 are incredibly crisp, clear and resolving and have earned many fans in the past 6 years.

Sennheiser HD800

What used to be uncommon, however now is more commonplace, is that headphones are more often coming with removable cables. While that is no-doubt a great thing (especially for owners of pets and office chairs), nearly every one of them is proprietary (much like how no one can settle on a portable balanced connector). The HD800 has its very own connector that even the HD700 doesn't share.

So, we've seen some various DIY HD800 connectors out there, there seems to be small barrel and larger barrel versions for thicker cable. Furutech recently hit the market with some fancier ones, namely the rhodium plated FT-800(R) or the CT-800(R) if you're a fan of carbon fiber. Both look quite a bit sleeker than the other variants out there, at least in my humble opinion. The connectors run roughly $50 for the generics and $98-$122 for the Furutech, not cheap at all, but I'd imagine the production run on these is fairly limited. I will also say that the Furutech is more pleasant to work with. You can snag the connectors from Soniccraft, among other purveyors of boutique audio goods.

Furutech FT-800(R)

FT-800(R) Internals

Soldering the HD 800 connectors requires a steady hand, a well lit soldering station and perhaps a magnifying glass. I'm convinced manufacturers are making these things more cumbersome to spite us all ;) Once I finish with each of these connectors, I fantasize about what a great surgeon I would be, truly world class! I digress. I do recommend isolating one of the solder joints with heat shrink as the terminations are oh-so-close, and you wouldn't want a short.

A bit of heatshrink is built up so the set screw has something to hold onto.

Microscopic pins

The Furutech connector then gets slipped in place, the back portion screwed on, and the set screw tightened down. Adhesive heatshrink is used to secure the connector and provide strain relief.

Heatshrink as strain relief

This particular cable is going to be made from Zynsonix Trebuchet cable, featuring super flexible ultra pure ohno continous cast copper in a sleek looking clear dielectric, and will be terminated with a balanced 4 pin XLR connector from Switchcraft. These new AAA-series XLRs from Switchcraft are really well made, with a very solid weight and feel, and they are only two pieces, which eases the build process. If you removed the logo and told me it was made by Furutech, I wouldn't bat an eye. Great connectors.

As you can see below, this cable features a hand braided litz of the slick looking Trebuchet ultra pure ohno continuous cast copper.

Trebuchet wire braid

Switchcraft AAA Series XLRs

Remember that 4 Pin balanced connector pins are typically:
1: L+
2: L-
3: R+
4: R-

And wrapping up, the final product:

Zynsonix Trebuchet HD800 Cable

I hope you enjoyed reading this DIYAudioBlog entry, please be sure to contact Zynsonix if you'd like a Trebuchet HD800 cable just like the above, or any other audio cable you happen to need. Until next time.

The Fine Print:

The above steps detailing the build of a headphone cable are for entertainment purposes only, and not intended to be used as assembly instructions. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted and cause physical harm to yourself, your surroundings or your property.