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i posted a tweet asking about why TRS balanced audio jacks can accept TS unbalanced plugs and have it “just work”, but i had to delete it because i immediately found out why:
TS plug -> TRS jack
(mono signal) T -> T (complement 1)
(ground) S -> R (complement 2)
(ground) S -> S
the noise reduction works like
output = complement₁ - complement₂
because the TS ground gets routed to complement 2, the result becomes basically
output = complement₁ - 0
so It Just Works! yay!
oh and to explain what balanced audio is: on professional audio equipment, you often use a TRS “stereo” jack to carry a “mono” signal as a differential pair. i'm calling the two signals in the pair the “complements”. it is like:
T = original signal
R = inverted signal or 0
S = 0
i'm getting a real kick out of finally understanding this. it seems like this complicated topic and then like… no, it is ridiculously simple and intuitive. it's a very, very simple technology that works super well. the world is so cool
in the balanced audio case btw the equation
output = complement₁ - complement₂
becomes
output = original - -original
output = original + original
output = 2 × original
and indeed, that's how balanced audio systems behave, the signal level is doubled :3
@hikari wait until you find out how the Instrument Landing System works
@whitequark i will have to dig into this later… am i going to find out that they figure out how to create a straightforward analog interference pattern that just magically tells the aircraft how to orient itself?
@hikari yes