I have been wondering - it's usually recommended to use two wires for the common negative and terminate the contact only at the end of headphone cable near the 3.5mm/6.35mm jack as it's said it should "improve" audio, in another words, reduce crosstalk. BTW, I'm not talking about "balanced" connection.
Digging through NwAvGuy's blog revealed this paragraph:
Nearly all headphones use a 3 wire connection via a 3.5mm or 1/4" phone plug (and some use 3 wire cables). The shared ground degrades crosstalk performance in inverse proportion to the load impedance. Lower impedance loads draw more current creating more drop in the common ground connection which shows up in the opposite channel. Just 50 mOhm of resistance at the headphone jack degrades crosstalk over 30 dB when you drop from 600 ohms to 16 ohm headphones.
Okay, I can understand crosstalk degradation, as negative poles are mixed, and that it's a significant deal for low impedances (below 80Ohm), butwhy does it happen at the connector?
2.5 metres of even good Mogami cable could result in over 200mOhm of resistance on the cable. Jack could add another 50 and PCB traces also 50.
I did the 4-wire connection, because I assumed capacitance is somehow related to the crosstalk. If it's about Z or R difference on the positive and negative pole, then simply using thicker gauge for the negative should partly solve the problem (or simply use the shielding, provided the parameters are similar).
Answers more inclined towards objectivism would be appreciated.
Question
iaval
Hi,
I have been wondering - it's usually recommended to use two wires for the common negative and terminate the contact only at the end of headphone cable near the 3.5mm/6.35mm jack as it's said it should "improve" audio, in another words, reduce crosstalk. BTW, I'm not talking about "balanced" connection.
Digging through NwAvGuy's blog revealed this paragraph:
Nearly all headphones use a 3 wire connection via a 3.5mm or 1/4" phone plug (and some use 3 wire cables). The shared ground degrades crosstalk performance in inverse proportion to the load impedance. Lower impedance loads draw more current creating more drop in the common ground connection which shows up in the opposite channel. Just 50 mOhm of resistance at the headphone jack degrades crosstalk over 30 dB when you drop from 600 ohms to 16 ohm headphones.
Okay, I can understand crosstalk degradation, as negative poles are mixed, and that it's a significant deal for low impedances (below 80Ohm), but why does it happen at the connector?
2.5 metres of even good Mogami cable could result in over 200mOhm of resistance on the cable. Jack could add another 50 and PCB traces also 50.
I did the 4-wire connection, because I assumed capacitance is somehow related to the crosstalk. If it's about Z or R difference on the positive and negative pole, then simply using thicker gauge for the negative should partly solve the problem (or simply use the shielding, provided the parameters are similar).
Answers more inclined towards objectivism would be appreciated.
Thanks
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