TIL that the iphone headset has a TRRS connector.
(Today I learned that the iphone headset has a Tip Ring Ring Sleeve connector.)
I also learned that the TRRS connector is apparently incompatible with some (maybe all?) 1/8" (mini jack) to 1/4" headphone adapters.
As I think I now understand it, the (usually) black ring is not a ring, but a conductor. The (usually) silver "gap" between the 2 black conductors is the actual ring in this equation. That's how a standard 1/4" or 1/8" (mini jack) headphone is called a TRS when it has 2 ring-looking-thingies. And on iphone headsets that have 3 conductors, there's actually just the 2 rings, hence the TRRS, instead of TRRRS.
So, I got a pair of IEMs (in-ear monitors) and wanted to try them in the studio. My Mbox 2 has a 1/4" plug for headphones.
Plugging said IEMs into my 1/8" to 1/4" adapter resulted in a karaoke effect (duplicate signal in both headphones and the "center" channel is gone).
I tried a different adapter and instead just got the left channel only.
For the record, the Apple iphone headset resulted on karaoke on both adapters, but it leads me to wonder if there are any 1/8" to 1/4" adapters that are compatible with TRRS headsets.
I found an 1/8" to 1/8" extension cable. That seems to have worked, though I'm not sure I'm getting a great signal since the extension cable is a little bit too big to properly fit into the adapter.
So here's how it goes right:
1/8" TRRS --> 1/8" TRS --> 1/4" TRS
Seriously, someone explain it to me.
I know the process for recreating karaoke in audio software and I think I actually understand why it works that way, but I have no clue how it applies to headphones.
I've been getting the karaoke effect for ages by doing things like pulling headphones slightly out of the audio player's jack or by having crappy headphones that were shorting out. And now this with the TRRS to TRS thingy.
I don't get it.
And if you're really curious, here's how you can get the karaoke effect in any (most?) audio software.
It starts with a stereo signal.
Depending on your software, you may now need to "split" the channels apart so that you can do the following on just the left or right channel (doesn't matter which).
Invert one of the channels.
Convert to mono.
And my loose understanding is that by flipping (inverting) one of the waveforms, everything that formerly was identical on each side will now cancel each other out, effectively removing the "center" channel.
So apparently this is what's happening with faulty connections on headphones.