rambomhtri
100+ Head-Fier
- Joined
- Jun 17, 2015
- Posts
- 225
- Likes
- 63
So, I got a WORKING but damaged TRRRS cable from a friend and I'm trying to repair some damaged parts in the cable (the external cloth/fabric that covers the inside cables is broken here and there). The cable works though, but it looks broken.
So, first I have to remove the back part of the jack, but I've tried as hard as I can and I can't do it, it's stuck and can't unscrew it at all (if it is that it's screwed to the TRRRS). I've tried with a pair of pliers, covering the jack with rubber/cloth, and still that thing won't move. I got very frustrated... So, I might end up buying a TRRRS plug, unless someone tells me how the heck this thing can be taken apart.
Now, the real problem is this one: I know how stereo cables work, I've repaired thousands of cables, with and without mic, I know the CTIA or OMTP standards and how to connect the pins. I've read and know theoretically how balanced cables work: in the music device you split the channel signal into 2 different cables/pins, in one of the cables you invert the signal, in the other cable you have the original signal; in the headphone's end you invert the inverted signal, you sum both signals and I suppose you then reduce it 50% to get the original signal. All of this is to reduce noise caught in the middle of the cable.
So, I believe you need:
PIN 1: original left channel
PIN 2: inverted left channel
PIN 3: original right channel
PIN 4: inverted right channel
PIN 5: ground (you mix the ground of the 2 channels)
So, I've checked the cable with a multimeter and in the headphones end I only have 4 connectors: 2 in the left channel and 2 in the right channel. Each pin of the jack plug is connected to one of those 4 connectors, but the sleeve of the jack plug is not connected to anything, and I don't understand how this balanced cable works. If I only could remove the jack cover and see the inside of it, I might understand, but anyways, none of this makes sense. Where's the ground to close the circuit? How in heavens this works?
By the way, the fabric cover is broken in one spot and I can see that there are only 4 cables inside the cable. Nothing makes sense...
Here's the schematic so you understand my problem:
So, the TRRRS is:
T: left channel inner pin/cylinder (green)
R: left channel pin/cylinder cover (light green)
R: right channel inner pin/cylinder (red)
R: right channel pin/cylinder cover (pink)
S: nothing? ???
Can anyone help me?
The cable looks like this one (it's for a Shure SRH1540 with a Sony Walkman MDR-Z1R I believe):
I'm also assuming that all the cable has no electronics inside (sounds dumb but you never know), I mean, all the work with the signals is done in the Audio player and headphone, I guess. This makes me ask this question:
A digital audio player is totally capable of splitting the left channel signal into 2 different signals, one of them inverted, and send them through 2 pins of the plug. Same with right channel. Total of 4 signals. Still don't understand in this cable where is ground and how the circuit is closed. Anyways, I don't understand neither how the headphone inverts one of the signals for each channel.
Does that mean that "balanced capable" headphones are able to invert one of the signals?
Does that mean that these headphones have electronics inside to invert one signal? What powers that circuit?
How the headphone knows if a balanced or unbalanced cable is connected?
So, first I have to remove the back part of the jack, but I've tried as hard as I can and I can't do it, it's stuck and can't unscrew it at all (if it is that it's screwed to the TRRRS). I've tried with a pair of pliers, covering the jack with rubber/cloth, and still that thing won't move. I got very frustrated... So, I might end up buying a TRRRS plug, unless someone tells me how the heck this thing can be taken apart.
Now, the real problem is this one: I know how stereo cables work, I've repaired thousands of cables, with and without mic, I know the CTIA or OMTP standards and how to connect the pins. I've read and know theoretically how balanced cables work: in the music device you split the channel signal into 2 different cables/pins, in one of the cables you invert the signal, in the other cable you have the original signal; in the headphone's end you invert the inverted signal, you sum both signals and I suppose you then reduce it 50% to get the original signal. All of this is to reduce noise caught in the middle of the cable.
So, I believe you need:
PIN 1: original left channel
PIN 2: inverted left channel
PIN 3: original right channel
PIN 4: inverted right channel
PIN 5: ground (you mix the ground of the 2 channels)
So, I've checked the cable with a multimeter and in the headphones end I only have 4 connectors: 2 in the left channel and 2 in the right channel. Each pin of the jack plug is connected to one of those 4 connectors, but the sleeve of the jack plug is not connected to anything, and I don't understand how this balanced cable works. If I only could remove the jack cover and see the inside of it, I might understand, but anyways, none of this makes sense. Where's the ground to close the circuit? How in heavens this works?
By the way, the fabric cover is broken in one spot and I can see that there are only 4 cables inside the cable. Nothing makes sense...
Here's the schematic so you understand my problem:
So, the TRRRS is:
T: left channel inner pin/cylinder (green)
R: left channel pin/cylinder cover (light green)
R: right channel inner pin/cylinder (red)
R: right channel pin/cylinder cover (pink)
S: nothing? ???
Can anyone help me?
The cable looks like this one (it's for a Shure SRH1540 with a Sony Walkman MDR-Z1R I believe):
I'm also assuming that all the cable has no electronics inside (sounds dumb but you never know), I mean, all the work with the signals is done in the Audio player and headphone, I guess. This makes me ask this question:
A digital audio player is totally capable of splitting the left channel signal into 2 different signals, one of them inverted, and send them through 2 pins of the plug. Same with right channel. Total of 4 signals. Still don't understand in this cable where is ground and how the circuit is closed. Anyways, I don't understand neither how the headphone inverts one of the signals for each channel.
Does that mean that "balanced capable" headphones are able to invert one of the signals?
Does that mean that these headphones have electronics inside to invert one signal? What powers that circuit?
How the headphone knows if a balanced or unbalanced cable is connected?
Last edited: