Speaker Amp to Headphone Converter Box

With the recent proliferation of low and mid sensitivity planar magnetic headphones from vendors such as Audeze and HiFiMan, it's easy to see why headphone enthusiasts are craving more power. Whether it's get that extra bass oomph and ability to listen at higher volumes with less distortion, having headphone amplifiers with between 1-6 watts is becoming more commonplace.

Since high wattage headphone amps are becoming more and more the norm, some have decided to hook up their headphones directly to the speaker taps. That's totally doable in a number of cases (see the speaker to headphone amp cable here) however there are other situations when this is not recommended, such as with tube amplifiers with output transformers. The output transformers can short if they don't have enough load, causing damage to your equipment.

Headphones also have a higher impedance than speakers, so while common speaker amps have outputs for 4, 8 and 16 ohms, headphones are often somewhere in between 32 and 600 ohms. You'll possibly hear noise on headphones from a speaker amp as they are more sensitive than speakers, which creates an unwanted noise floor. So to get rid of these problems, a small resistor network is necessary to modify the load for your amplifier, and reduce the audible noise.

A resistor for each channel is needed to attenuate the volume so that it is more compatible with headphones and help reduce noise, and additional resistor is needed to reference ground (again for each channel). These resistor values will vary depending on the impedance of your cans.

The project starts with a small Hammond Aluminum case. Hammond is the standard when it comes to small project boxes like this. You can get this in anodized red, blue, black or plain silver. the usual suspects have it: Mouser, Digikey and Angela.

Hammond Black Anodized Case

The first task is to punch the hole for the headphone jack. I'm using a Neutrik locking in this case. This particular build is a single ended (e.g. not a balanced headphone jack with isolated grounds). This is only possible IF AND ONLY IF the amp's left and right ground is shared. This is simple to check with a multimeter.

To punch the hole I'll be using a Greenlee punch. This makes a nice clean opening to install the Neutrik locking plug. These are expensive, so only get one if you plan to get good use out of it.

Pilot hole

Fixing the Greenlee in place

And the punched hole

Next is the task of drilling out and installing the binding posts on the back. I found that a vertical arrangement allowed the panel space to be used most effectively.

Binding post installed on back panel

The panel holding the binding posts is fastened to the case with four screws, and two teflon solder posts are mounted on the base of the unit. These can be found at VT4C. The resistors for this application need to dissipate power, and therefore heat, and they need to be large for that purpose. There are various power resistors out there that fit the bill, sandcast, metal oxide, wirewound, etc., but they can't degrade the sound, so I am using Mills 12 watt non-inductive wirewound resistors as we don't want any induction screwing with the impedance. The Mills are well thought of for good sound quality, so it was an easy choice. I've also used the larger Kiwame 5W carbon film resistors in parallel.

Resistors wired up

For the wiring I chose to use some choice Kimber TCSS copper in Teflon. 

Kimber wiring

The front panel is secured with four screws, and the top aluminum panel is slid back into place. I adorned it with a nice little branding element. 

Speaker Amp to Headphone Converter Box Front

Speaker Amp to Headphone Converter Box Back

UPDATE 2-21-2017: These have been rather popular and Zynsonix is offering these for sale in different configurations. Below is a unit with 4 pin XLR and Cardas binding posts.

And here is a unit with switchable inputs in a larger box.

I hope you enjoyed this post, please contact Zynsonix if you'd like to purchase a unit.

The Fine Print:

The above steps detailing the building of a speaker amp to converter box are for entertainment purposes only and not to be performed under any circumstances. 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. Please keep this in mind.

Beyerdynamic Balanced Removable 4 Pin Mini XLR Mod

A client recently sent me one of my favorite headphones to modify, a Beyerdynamic DT770. The DT770, DT880, DT900, and similarly the T1, T5p, T70, and T90 are all intuitive to work with and respond well to new cables and mass loading.

Beyerdynamic DT770 - Pro 80 ohm version

This DT770 would be getting a removable cable mod, which includes the installation of a mini XLR in the headphone cup so the cable can easier be removed for transport or to perhaps have separate cables for portable and home use. The DT770 has room for a mini XLR jack on both the left and right cups, however this user preferred the simpler single ear input. Since I was already going through the trouble, I wired the headphone for balanced operation just in case he ever switches over to balanced listening in the future. The great thing about mini XLR jacks is they lock, so no need to worry about them slipping out like a 3.5mm or 2.5mm. Also, TRS connectors can loosen over time, however this is not as likely with the mini XLR connectors.

Below is a look at the interior driver. As you can see, the DT770 driver is unique in that it has a felt and plastic ring encircling the center, which reduces the sound wave reflection inside the cups.

DT770 driver and felt/plastic ring

Because the felt and plastic circle reach the plastic backing of the cups, any added mass damping should be clear of interaction. Below you'll note the Dynamat Xtreme installed is a small circle which is measured to fit neatly inside the cup and not cause any clearance issues with the driver. 

Dynamat Xtreme used as mass loading

Beyerdynamics used to come with a round hole, but it's square now that they've revised the manufacturing to some extent. I carefully increased the size of the hole diameter toward the round side of the cup with a Dremel to prevent the plug from getting in the way of the driver. The hole does not have to be absolutely round as the ridge on the mini XLR plugs will cover minor imperfections. 

Dremeled hole for 4 pin XLR mini jack

A three or four pin mini XLR jack can be used. In this case I used a four pin as I wanted the user to be able to upgrade to balanced down the line if he wanted, but in other cases, a three pin can be used as the ground is wired shared as default. Please note the position of the jack, if it is not close to the rounded edge like this is, the driver will not fit back in. Dremeling down the metal casing of the jack where it meets the driver may help a little bit, but will reduce the integrity of the jack if too much is taken off. 

Nice, clean fit

Wire should be run from one side of the headphone to the other as this is going to be single entry. A twisted pair of Zynsonix Xev silver clad wiring is prepped and sleeved with black polyolefin heatshrink tubing. 

Wire to run from one cup to the other

This can be wired however the user prefers, however I used the XLR standard (pin 1 = left +, pin 2 = left -, pin 3 = right +, pin 4 = right -). 

Wired with Zynsonix Xev silver clad wire

Before re-installation, the driver solder tabs are cleaned of the stock solder.

Solder tabs cleaned of original solder

The new Zynsonix Xev wires are installed using fresh Cardas silver content solder and the felt/plastic cups re-installed. 

Driver wired up and ready

The foam is reseated on top of the drivers and the earpads are reinstalled, so we have a nice clean 4 pin mini XLR input on our Beyerdynamic DT770 now. 

Installation of mini XLR jack complete

And finally we have the finished product featuring some cool colors, in this case rust with a black accent, terminated with a Switchcraft gold plated mini 3.5mm plug and a Neutrik / REAN mini XLR. Now these old Pros are ready for some stylish listening! 

I hope you enjoyed this post, please contact Zynsonix if you have a pair of Beyerdynamics (or any other headphone) that you'd like recabled or modified.

For more full-sized Beyer headphone mods, check out the Beyerdynamic T5p Recable and the DT880 Recable.

The Fine Print:

The above steps detailing the modification and re-cabling of a headphone are for entertainment purposes only and not to be performed under any circumstances. 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. Please keep this in mind.

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. 

Steampunk Grado with Turbulent X Drivers

I've heard plenty of good things about the Turbulent X drivers made to fit Grado Labs and Alessandro headphones, so I thought it would be fun to build a new pair. Anyone who's modded a pair of Grados and ran a few Google searches knows that there are hundreds of options out there, from Sennheiser pads to aftermarket leather headbands, to wood cups from numerous manufactures large and small. So if you don't want your Grado to look like everyone else's Grado, there's nothing stopping you from some serious customization.

I'm no stranger to modding Grados, my last being an Alessandro with custom wood cups and a cable made from Cardas copper. This time I decided to do something that I'm pretty sure no one else has tried, a Grado with copper leafed mahogany cups. Copper leafing is process where you put down a base coat of paint, sand, then put down adhesive sizing, then lay extremely thin sheets of copper down and burnish them onto the wood, then cover with some protective sealant. You'll see some other examples of this in my custom built tube amplifier bases.

I began with a pair of mahogany wood cups and performed the copper leafing process. You'll note that the look is not perfect, it has a unique weathered look that make it nice for a steampunk-esq look. It actually weathers over time a bit as well, which only makes it look better in my humble opinion.

Copper leafed Grado cups

Inside the cups, I'd be using some unique grating I had powdercoated a copper color. This was cut for a tight fit and affixed with adhesive.

Powdercoated grates

Since Zynsonix is known for it's audiophile quality wire, I wouldn't be using any run of the mill cable, but some really impressive wire that was custom-made for Zynsonix, particularly for headphone and portable cable applications.

Custom Zynsonix Trebuchet wire

This is a special 24 gauge wire with high flexibility and low memory properties called the Trebuchet. It uses a high-flex clear PE dielectric and ultra pure ohno continuous cast copper for the finest sound quality. 

The mini connector is the well-made Amphenol 3.5mm. Unlike many other mini connectors, it works well with portable DAPs and iPhones in thick cases. This was braided into a litz, then into two twisted pairs, one for each cup. 

Each wire was run into the cup, soldered directly to the Turbulent X driver, then test fit to verify where the wire would fall. The wire was then secured with a zip tie and some hot glue. If it's good enough for Grado, it's good enough for me ;) It is nice to use hot glue as it is removable later for future mods. 

Turbulent X Drivers - Green marks positive in this case

I needed a donor pair of Grados, this would be a pair of used SR-60s I located online.

Some of the best value cans out there, the SR-60

The headband was removed with a twist of the plastic, then the Turbulent Labs headband was installed. This is much comfier than the stock headband, although not the finest Grado headband I've used. That honor would go to JMoney. I do like the color on this one though. 

Next was the process of removing the stock SR-60 cups and installing the copper leafed cups. The forks on the stock unit needed to be dremeled down a bit for adequate clearance, but other than that, pretty straight-forward.  

Well now I have a very unique Grado build with some great sounding Turbulent X drivers and the superlative Zynsonix Trebuchet wire, a match made in heaven for my ears. The sound is crisp and detailed yet full-bodied and dynamic. 

Please feel free to contact Zynsonix if you'd like your headphone recabled with the Trebuchet wire, or if you'd like a custom cable made from it, you won't find it anywhere else.

The Fine Print: The above steps detailing the recabling of a headphone are for entertainment purposes only, and not to be performed under any circumstances. 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. Please keep this in mind.