Building a Custom Lightning Audio Cable

I don't think it's alarming to even infrequent readers of mine to find that I tend not to replace things if I don't have to. I also tend to be a fan of things that have wires versus their wireless counterparts with some very specific exceptions. I've been using a pair of Bose QuietComfort 25 headphones for probably 10 years, if not longer. They're fantastic. I use them all the time in loud environments as hearing protection. I wear them whenever I fly commercial, mow the lawn, and use just about any power equipment. The only complaint I have is that the 3.5mm jack on the end of the cord is right-angled. This is nice if I am using it on a laptop but when paired with the Apple Lightning to 3.5mm Headphone Jack Adapter it ends up being both obnoxious in a pocket and stressful on the Lightning connector. I tried several after-market adapters but they all worked poorly compared to the Apple one (not entirely surprisingly) so I ended up buying several official Apple ones on eBay to simply have a few spares for when I ended up destroying them.

Well, I got tired of that. I bought a replacement cable for the QC25s and cut the 3.5mm end off to see if I could simply attach it to the Lightning end of the Apple cable. It turns out you absolutely can. The result fits so much better in the pocket and is a lot stronger than the flimsy Apple adapter is. The salient detail is the pinout of the Lightning end of the Apple adapter and the trick is that the tip includes a plug detect feature so you need to connect both the green with copper stripe wire and the red wire together to the tip so the i-thing sees something 'plugged in'. To save you the work of testing the jack end pinout, this is what I came up with.

Apple Lightning to 3.5mm Headphone Jack Adapter Pinout

Addendum: 1/26/2026

Well after nearly two years the (fairly old and worn out before modification) Apple lightning plug failed. Apple's cables are obnoxiously flimsy and lack decent strain relief at the best of times and the 3.5mm to lightning dongle may have been one of the worst ones ever. The cable itself was so thin and the jacket so elastic it was just begging to fail.

I replaced it with a UGREEN 3.5mm to lightning adapter which seems much nicer, has a moulded strain relief and a braided outer covering on the cable. The wiring is quite a bit different though. Thankfully the MFi chip seems to still be in the lightning plug side so after simply probing around the wires on the jack side I was able to come up with the pinout and repair my cable.

UGREEN Lightning to 3.5mm Headphone Jack Adapter Pinout

Red and green are shorted when a plug is inserted into the 3.5mm jack so they are tied together. The copper, copper with red and copper with blue, copper with green pair appear shorted at the jack end all the time so they also get tied together. A bit of liquid electrical tape and heat shrink tubing closed everything up and once again I have a cable that Bose should have made in the first place.