Hi, i am trying to help my brother design a sort of joining/breakout board for some sort of 8 channel audio cable.
Basically we need to join the end of the cable to other cables and we tought the easiest way was to use a small pcb that has two rows of pads with short traces conecting them, but we heard that the pcb traces would have crosstalk if traces run parallel to one another.
I am wondering if that would be a real issue for this use case. The pcb would have ground plane in between all the signal traces.
It would be used for line level signal.
There is a pcb photo in attachment, the board size is around 50mm x 11mm
Note that the pcbs are not final, this is just some testing and messing around
Basically we need to join the end of the cable to other cables and we tought the easiest way was to use a small pcb that has two rows of pads with short traces conecting them, but we heard that the pcb traces would have crosstalk if traces run parallel to one another.
I am wondering if that would be a real issue for this use case. The pcb would have ground plane in between all the signal traces.
It would be used for line level signal.
There is a pcb photo in attachment, the board size is around 50mm x 11mm
Note that the pcbs are not final, this is just some testing and messing around
Attachments
If you are using this for balanced audio lines I would not put a ground plane in between the + and -. I would only use a ground to separate each pair of + and -.
Also - a ground plane shared by all 8 channels could cause problems. If the source is a single 8 channel DAC, ADC or tape deck, should be fine. But if it is 8 different pieces of outboard gear, what if one of the units has some noise on the ground signal. That would then infect all the other channels in your board.
Grounds are usually separate in quality patch bays , and 8 channel audio cables
from Mogami , Canare, etc = all have separate ground lines for each channel.
Also - a ground plane shared by all 8 channels could cause problems. If the source is a single 8 channel DAC, ADC or tape deck, should be fine. But if it is 8 different pieces of outboard gear, what if one of the units has some noise on the ground signal. That would then infect all the other channels in your board.
Grounds are usually separate in quality patch bays , and 8 channel audio cables
from Mogami , Canare, etc = all have separate ground lines for each channel.
Thanks, i am guessing that it wouldn't be much of a problem with balanced signal, But what about the unbalanced, would small pcb like this cause crosstalk ?
I wouldn't worry about with crosstalk below 1MHz on something of that size, there's far too little capacitance to affect an audio signal. These will all be low impedance sources so very little susceptibility to a pF or so of capacitance. If you had a low impedance signal next to a high impedance signal, that might well be cause for concern.
At 20kHz 1pF is 8 megaohms impedance. Typical low impedance audio sources are ~100 ohms. That small board might have less than 1pF between signals too, 1pF is the capacitance of about 0.5 square cm of FR4 that's 1.6mm thick.
The part that might exhibit cross-talk is the cable itself if its carrying multiple signals over distance and not well individually screened.
At 20kHz 1pF is 8 megaohms impedance. Typical low impedance audio sources are ~100 ohms. That small board might have less than 1pF between signals too, 1pF is the capacitance of about 0.5 square cm of FR4 that's 1.6mm thick.
The part that might exhibit cross-talk is the cable itself if its carrying multiple signals over distance and not well individually screened.