Balancing the AKG K702 Headphone

The AKG K702 headphone is quite simply a black AKG K701 heaphone with a removable mini 3 pin cable. It's very nice to be able to remove the cable from a headphone with the click of a button, which is where the 3 pin mini-XLR comes into play. Switchcraft is well known for these connectors and offers them in a number of different pin configurations. Clicking the little black button on these connectors allows them to disconnect from the jack, so if a user runs over their cable with the wheel of a chair, desires a shorter or longer cable, or wants a cable of higher quality, it's very easy to swap a new cable in. Zynsonix offers replacement cables for the K702 among other headphones with removable cables if one is in the market.

With the existing 3 pin connector in the AKG K702, the two grounds for each channel are commonly connected. This won't work for a balanced connection to a balanced headphone amplifier where the grounds are run separately, so the existing three pin connector will be removed in favor of a 4 pin mini-XLR from Switchcraft.

In this post, a pair of K702s will be getting repaired with some high quality Eys 99.999% pure silver wiring (5Ns) in PTFE tubing. This particular pair of K702s had the previous jack accidentally ripped out (perhaps the headbanging got a bit too frenetic ;) ), but luckily everything inside is still in good working order. (I've found that with other AKGs, getting the existing jack out can be quite tricky, requiring a Dremel tool and quite a bit of patience). One will notice in the photo below, the white wire is the ground, in which both the left and right ground are commonly connected. In order to get inside the plastic shell, the grill needs to be rotated using a pair of jewelers screwdrivers, then two small screws are removed from underneath the grill.

AKG K702 opened

The first task would be to wire up the Switchcraft 4-pin mini XLR jack with silver wire, this would be replacing the existing wire within the headphone. Each piece was made a little longer than necessary and color coded for easy reference with electrical tape. The solder joints were covered with very small diameter heatshrink tubing to prevent the Teflon tubing from moving while the jack was being installed.

Silver wire soldered to Switchcraft mini 4 Pin jack

Now the jack could be slipped inside of the existing plastic shell. No dremeling or filing necessary is necessary when using a genuine Switchcraft jack. A strong adhesive does need to be used to keep the jack in place however. 

Switchcraft jack installed in the plastic shell

The stock wiring was removed at this point, a desoldering pump used to get off excess solder, and the new wires soldered in place. The solder points for the left driver are at the left-most and right-most points, and the solder points for the right driver travel along the headphone band, which are both closer to the center. Silver wiring was wired to the to the terminals and the plastic shell and grill were reinstalled. 

The plastic shell being reinstalled on the K702s

At this point, the matching silver cable could be built. Starting with a 4 pin mini XLR plug, the silver wires were soldered in place and small diameter heatshrink tubing was placed over the joints to prevent slippage of the Teflon tubing.  

4 Pin Mini XLR plug with wires soldered in place

The metal jack barrel was then slipped in place over the plastic piece housing the contacts. 

Metal barrel covering plastic housing

The wires were then braided in a litz formation and the strain relief clamped down on the wire tubing to prevent movement. 

Silver wire braided and strain relief clamped

The cable was then sleeved with soft black nylon multifilament. The remaining piece of the jack was filed to allow for the large diameter cable, then slipped over the sleeving and screwed to the metal barrel. A piece of adhesive black heatsrhink was added to act as an additional strain relief and help to keep the sleeving in place. 

4 Pin mini XLR completely installed

Cable sans mini connector

A Switchcraft mini connector could now be installed. You can see more details on a mini connector being installed in this previous post: Silver Plated Copper Mini to RCA Cable. The cable could now be clicked into place on the now repaired AKG K702. The mini connector is inherently non-balanced, but the user can now easily upgrade to a balanced cable when they are ready.

Completed cable on the AKG K702 headphones

UPDATE (6/14/12): The Quincy Jones Q702s are nearly identical, although the internal jack proved to be much more difficult to remove. The Q702s below were recabled using Zynsonix Ecs ultra pure ohno cast copper in Teflon.

Rewired with Zynsonix Ecs wire

These AKGs feature a fully balanced cable. 

Quincy Jones Q701 Balanced

I hope you found this post entertaining. Please be sure to contact Zynsonix if you'd like to take the music on your headphones to the next level.

The Fine Print:

The above steps detailing the repair and 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.

 

Mini to RCA Cable with some ViaBlue Connector Bling

The mini to RCA cable is a great option when you want to plug a portable device like an iPod / MP3 player or portable CD player (anyone still have one of those? ) into your home stereo. Modern smartphones let you stream radio stations and services like Slacker Radio and Pandora, why not plug all those great options right into your stereo?  You may have seen my other Mini to RCA Cable blog post, but I will be putting a little twist on the basic cable design with some beautiful ViaBlue connector bling.

ViaBlue is a relative newcomer in the vast sea of audiophile boutique connectors from companies like Cardas, Kimber and Audioquest. Their connectors are designed in Germany and have a unique visual appeal with their gold plated tips and matte black shells. Building using their connectors requires a little bit more effort than other connectors, at least in my experience. The design makes use of allen head set-screws, which require one to build up a large amount of heatshrink so the screws have something to "bite into" as a strain-relief system. I personally prefer a crimp-around ground terminal or the system that Furutech and Neutrik uses with some of their connectors which compresses a plastic sleeve with plastic ridges that secures the cable, but some sacrifices must be made for good looks I suppose ;) 

My favorite connector that ViaBlue makes, the Y-split cover, specifically the SC-2 Splitter 44920 in this particular build, is great for covering up unsightly "Y" splits where the whole cable run enters and two runs exit. These splitters are perfect for headphone cables, mini-to-RCAs, speaker cables and a variety of other applications. 

The ViaBlue SC-2 Splitter

The other connectors that would be used for this build are the T6S RCA Plugs and the T6S 3.5mm Phono mini plug. All make use of the set screw strain relief system and have the same sleek logo printed on the barrel. 

A bevy of beauties

The wire that would be used for this build is military spec silver plated copper in PTFE dielectric. The cable is a hand-braid of four wires, two for ground (or return), one for left signal and one for right signal. The wire in braided as a four wire litz for about five of the six feet of this cable, the final foot being two twisted pairs. 

Hand braided litz of silver plated copper wire

Once the wire has been braided, it can be sleeved. Black nylon multifilament was chosen for this purpose as the matte black on the connectors will match nicely with the soft black nylon. 

Cable sleeved in black nylon

The first step once the cable is sleeved is to attach the SC2 Splitter where the cable splits. 6 or so layers of heatshrink (preferably adhesive) must be built up so the splitter can get a grip on the cable and not move around once it is completed. 

Heatshrink built up for ViaBlue Splitter

The heatshrink should be as large as possible but still be able to fit through the bottom of the splitter. The gold allen screws are scewed into the heatshrink tightly, but not so tightly that they strip. 

ViaBlue Splitter in place

Next comes the mounting of the RCA connectors. The two gold allen screws are removed to gain access to the solder tabs within the plug. 

Opened ViaBlue RCA

Heatshrink is built up at the ends so the screw can grab onto it, in this case it is 3 pieces of 1/4" heatshrink overtop of 1/8" black nylon multifilament.

Extra heatshrink added to ends of cable 

The black plastic spacer and barrel are slipped onto the wire before soldering.

Wires soldered to the ViaBlue RCA

Everything is lined back up and the screws are replaced in the unit. The other RCA is installed the same way.

ViaBlue RCA fully attached

Next comes the 3.5mm mini connector. 

Opened ViaBlue 3.5mm mini connector

Two layers of 1/4" heatshrink are placed on top of the 3/8" nylon sleeving on this side of the cable. The black plastic spacer and barrel are slipped onto the wire before soldering. The solder connection to the left and right are rather close, so I added a piece of heatshrink to keep them secure and isolated. 

Wires soldered to the ViaBlue mini

The barrel and plastic spacing piece are lined back up and the screws are replaced.

ViaBlue mini fully attached

With all connectors in place, the signal and resistance is checked with a multimeter to verify signal continuity and that there are no shorts. The cable is now complete.

Mini to RCA with ViaBlue connectors

A second angle

I hope you enjoyed this documented step-by-step process on creating a mini to RCA interconnect with ViaBlue connectors. This cable was a special request taken at Zynsonix, where you can purchase the same cable or one built completely around your specifications.


The Fine Print:
The above steps detailing the building of a cable 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.

Using Silver Plated Copper for Speaker Cables

We've all seen the restrictively expensive speaker cables out there on the market. Most of them look incredibly awesome and have sophisticated, patented geometry, but sometimes you'll notice that there was some scrimping done with the quality of the conductors. When you're paying good money for cables, why settle for Polyethylene or Poly-Vinyl-Chloride (PVC) dielectric when Teflon (PTFE) is better?

I went into a brief explanation regarding the dielectric constant of Teflon in my post regarding Kimber TCSS wire, but briefly, it's a synthetic fluoropolymer that was developed by DuPont and has a dielectric constant of 2.1, lower (better) than all other noted cable dielectrics.

Silver-plated copper is a type of wire covered with Teflon that's widely available for industry applications. Belden offers it, among a number of other companies, and you'll find a number of military spec varieties of different vintages. The cost is relatively low compared to audiophile boutique wire and the quality is generally high. You do have to keep an eye out for tin covered wire though, it looks quite similar but sounds different, and not preferable in my experience. The reason these wires have silver or tin plating has to do with the extrusion process of Teflon, it's much easier to extrude it over silver or tin than copper from what I've read.

I've built a number of interconnects and speaker cables using silver-plated copper. While there is a vast variety of Teflon coated interconnect wire floating around out there (Neotech, Mundorf, Kimber, Legenburg, etc.) but when it comes to big, thick, burly speaker wire, that variety really dwindles away, I'd imagine due to production costs. So enter the silver-plated copper; you can snag some nice thick 10-12 gauge wire under a buck a foot, whether you're running one or two conductors per terminal, it's still works out to a lot cheaper than fancy boutique wires.

You can always dress it up and make it look nice too if you want ;) Here's a few I've put together:

2 x 10 Gauge - Black Nylon Covering, Rhodium Bananas

4 x 12 Gauge - Copper Bananas and Spades, Carbon Reflex at the "Y" Split

Above in Detail

2 x 10 gauge - Cotton Reinforced Hose covered with black Techflex

If you're looking for some nice quality bananas and spades, I've found that Homegrown Audio has a nice selection for reasonable prices. The sound from a silver-plated copper speaker cable is crisp and clear. Give it a shot before you lay down some serious dough on boutique wire.