Balanced XLR to RCA Cable

Balanced XLR interconnects are what many people consider to be a superior connection between components. Typically found in Pro-audio equipment, they feature three wires rather than the two in an unbalanced RCA interconnect. The three wire system includes hot, neutral and ground. Current flows through the hot and neutral with both an inverted and non-inverted version of the signal. The component only needs to sense the difference between the two signals which assists in rejecting common noise. Common noise includes RF and ground loops, both of which can be quite annoying.

Some higher-end components have taken notice that balanced XLR interconnects can be more ideal and include them as optional inputs and/or outputs. Unfortunately there are many components that do not offer them, so you may end up with a component with XLR outputs and another with only RCA inputs. In this case, an XLR to RCA cable can be used.

The parts needed are relatively self explanatory. An XLR connector on one side (may be male or female depending on the component), an RCA plug on the other side, and three wires to connect them. One can also use only two wires and short the XLR internally between pins one and three. Note the diagram below that pins one and three are connected to the sleeve of the RCA and pin two is attached to the tip.

Starting with a Neutrik NC3-FXXB (3 pin female XLR connector), each of the pins are identified by the small number that's actually printed on the front of the plug.

The inside of a Neutrik NC3-FXXB

If you follow this blog, you've already seen countless litz braids of silver plated copper in PTFE, so we will skip that and move on to the soldering of the individual wires to the solder tabs on the Neutrik XLR connector. Each joint should be heated quickly but adequately (not too long which could melt the plastic casing) which will result in nice shiny joints.

Wire soldered to the Neutrik XLR

Next comes the sleeving. In this particular case, the braided wire is covered with soft black nylon multifilament. The black nylon multifilament is made by the company TechFlex and has a nice vintage look. It can be purchased from online retailers like Cable Organizer and WireCare. In order to sleeve the wire, a hot knife is used to cut the sleeve to prevent fraying, it is then slowly slipped over the braided wire and once completely covered, the other end is cut with the hot knife. To hold the sleeving in place, adhesive heatshrink is used on the ends where the strain relief from the plug will eventually cover the cable.

Sleeved cable

As you will note below, the strain relief system is placed over the heatshrink to give it something to "grip" to. The metal barrel is then slipped over the front of the XLR plug.

Barrel and Strain Relief

The boot can now be slipped over the other end of the cable and screwed in place to secure the barrel and strain relief system. Neutrik does offer the FXX line with a number of different colors. I'm using red here to denote the right channel. 

XLR side is complete

Moving on to the other side of the cable, the RCA connector will be attached to the cable. First, the metal barrel for the RCA is slipped onto the cable, then the RCA connector soldered in place. Both the number 1 connection and number 3 connection from the XLR side are soldered to the ground or "sleeve" in this particular configuration. The number 2 connection is soldered to the signal or "tip". Once soldered in place, a small piece of heatshrink (in this case red) is used to prevent shorting between the ground and signal. The nylon sleeving is then slipped as far forward as it can go and the strain relief on the sleeve is crimped around it.  

RCA connector soldered in place

Now another piece of adhesive heatshrink is placed over the bottom of the RCA connector to act as additional strain relief and further secure the sleeving.

Heatshrink sleeving in place

Now the metal barrel of the RCA can be screwed on. The cable is now complete and can be tested. 

A single completed cable

The pair of XLR to RCA cables

I hope you enjoyed this post. If you are interested in purchasing a completed XLR to RCA cable, please contact Zynsonix.com.

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.

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.