Fancy an XLR balanced cable for the HD800 without spending €300 for Sennheisers? Cheap skate recipe is as follows requiring about €10 worth of parts, a brave pill, and a little soldering skill. Parts needed are,
Neutrik NC4FXX-B Female four pin XLR :
http://www.neutrik.com/en/xlr/xx-series/nc4fxx-b
Neutrik NC4MXX-B Male four pin XLR:
http://www.neutrik.com/en/xlr/xx-series/nc4mxx-b
The stock cable is a very nice design with a two separate cables for the left and right channel, each having a + and - wire wrapped inside an outer shield. The other two black strings are only rubber to give the cable assembly some strength. The four of them are all spiral wound together and wrapped in two layers of cloth.
1) Take a brave pill and snip off the stock TRS connector with approx. 4" of cable attached. Peel back the cloth layers on the headphone cable to expose the two cables inside, then carefully strip about half an inch of rubber off each one. Separate the shield wires that are wrapped around the two inner conductors and twist all the strands together as shown below leaving you will two wires and a shield wire for each channel.
2) Disassemble the male four pin XLR socket and slide the strain relief onto the headphone cable. Strip back ~5mm on the Red and White wires and solder the Red onto Pin1: Left +, and the white onto Pin 2: Left – of the XLR socket. Then Take the Green and White wires and solder the Green onto Pin3: Right +, and the white onto Pin4: Right -. The two remaining shield wires then connect to the ground solder tab on the XLR connector. Slide the connector inside its housing and screw the strain relief onto the plug and you’re done, as shown below. For a final sanity check take a multimeter and using the continuity setting ensure you have a good electrical connection from each of the four pins to the connectors at the headphones, and also confirm that you have no shorts between pins. The outer bodies of the connectors at the headphones should also have continuity with the XLR outer shell.
3) Optional if you want the ability to plug into regular TRS sockets: Disassemble a female four pin XLR connector and slide the strain relief onto the short cable attached to the TRS socket. Prepare the wiring the same as step 1, and then solder the wires onto the XLR socket using the same pinout as listed in step 2. You will then have a short XLR to TRS adapter as shown below.
4) Final pic showing the adapter plugged onto the end of the headphone cable. The nice thing about this mod is it preserves the correct wiring for use with regular non balanced TRS sockets, and also for balanced XLR sockets using the same cable.