[LAD] crosstalk between jack clients/ports?

[Vaclav Mach]

Problem solved.

The crosstalk occured in wires connecting the motherboard and the front 
panel mic and headphones jacks. I disconnected this cable and the echo 
disappeared.

Thanks for your advices!


On 05/27/2015 11:04 AM, Adrian Knoth wrote:
> On 05/27/15 10:35, Gordonjcp wrote:
>
>>> I want to avoid the echo and I have two ideas where the problem can be:
>>> 1) there is a crosstalk between jack ports/clients
>>> 2) there is a crosstalk in my HW (mainboard sound device with
>>> intel_hda driver)
>> Most likely the latter.  Check you haven't got the mix parameter
>> turned up.
> What Gordon said. There is absolutely zero crosstalk in digital systems,
> it's a concept from analogue.
>
> In a digital system, each port/channel is a memory buffer. Nothing
> accidentally touches this buffer, and if so, the signal would be totally
> ruined (think of random bit flips in digital samples).
>
> For an attenuated and delayed signal, you'd need to multiply and add the
> initial signal, e.g., out=0.4*remote[-X]+local. This doesn't happen by
> accident, something is actively feeding the output back into the stream.
>
> I agree with Gordon's assessment that PC2 is most likely recording from
> Mix ("record everything that goes to the hardware outs"), thus creating
> a delayed loop.
>
> The fix is to open alsamixer -c X and choose "Mic in" in the records tab
> instead of "Mix".
>
>
>
> HTH
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