[BiggerHead]

This post is about 10 years late to be interesting for most people, but there actually a couple of major airlines out there in the world still using those two pin headphone jacks, even with entertainment systems.
 
So I walked into a bose store and asked if they had an "ariline adapter" and they pulled out a thing with male mono input plugs and one 3.5 stereo socket as needed.  The thing is kind of nice because actually one of the mono plugs isn't mono, it's stereo and the other one can fold away, so then you can use the adapter any time so you don't have to put somewhere and lose it.
 
 
... except that they didn't mention that it has a 36 db attenuation!
 
I took the thing apart and sure enough it's full of 4 resistors.  I started measuring and it's the usual L resistor scheme on both left and right with  about 2kohm in series and 350 ohm in parallel to the output.
 
On amazon this same adapter is sold for QCX models etc but says also compatible with any headphone.
 
So is it just me or is this crazy?  Some attenuation on an airplane, maybe 10db, could be useful I guess for hiss reduction.  I've even read that it's possible to blow out iems with airline audio systems, but this was 20db too much anyway and if I did want an attenuator normally, for my 32 ohm cans, I sure wouldn't want one creating a 350 ohm output impedance!
 
I did read somewhere that older versions of these airline systems(probably not the ones I care about) expected 600 ohm devices, but this is presenting 2kohms!
 
I suspect that this works fine as input to a high impedance device, possibly like a bose amplified headphone.  I'm surprised if it helps a device like that, but it maybe wouldn't hurt it.
 
So is there any reason I should not lay some solder across these resistors? (obviously not the parallel one)  Is there some reason I should actually want this setup?  Is this setup just legal protection for bose?

 

[BiggerHead]

Pretty surprised nobody has an opinion on this one.  maybe it's the wrong sub-forum.  For reference, the resistors are actually 1.5kOhm and 300Ohm, as revealed with some magnification (my measurements weren't very good).
 
Anyway, I'm going to bypass this nonsense.

 

[BiggerHead]

Done. Works. A bit trickier than it looked.  Would just buy a different one next time, but these things can be hard to find.

 

[johnston21]

Why use at all? They were designed for NC purpose. Surely the cans will work without it, noting Shure tends to still include in the box.

 

[BiggerHead]

Something about  satisfying results with two female sockets at once.  You can fill in the blanks.
 
Maybe you missed the part about the dual-mono jacks still existing on some flights?  Maybe you've never seen them so didn't get it?  Back in the days of yore all airplanes had two mono jacks, one for each ear, with about a cm or so spacing, and they distributed special stereo headphones with a plug that fit this arrangement.  I think it's not worth stealing a lousy $2 headphone to try to fix the plug, but for the airline this $2 savings equates to thousands.
 
If you plug a stereo headphone into either jack, you will hear that channel only... in your left ear.  If you're lucky you can get the plug just right to send the mono signal to both ears at least. Or you can use an adapter.