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February 7, 2013

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.

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