Diagnostic Skills Required Please

[Gmanuk101]

Hearing an electrical frequency noise from the Aux channel - sounds similar to a sawtooth wave.

Here is how it's reproduced.

1. 3.5mm to RCA from Soundcard output to AUX chan on AMP
2. 3.5mm to RCA from AMP Tape Out to Soundcard Input

When AUX chan is selected and both 3.5mm jacks are connected I hear the sound. I do not hear the sound if the Tape Out is removed from the soundcard input.

I am not sure what is causing this, any ideas?

To be clear, the sound does not occur when in the following scenario:

Only one 3.5mm is connected.
AUX only is good
Phono is good
Tuner has not been tried

Could it be an earthing on the soundcard? (that's a random guess)

[Reid Malenfant]

Yep, sounds like an earth loop :rolleyes:

[Gmanuk101]

I fixed it, the soundcard forums suggested it was the card being not in audio creation mode, all good now

[Reid Malenfant]

Audio creation mode... Yeah I know that - not! :lol:

Glad you got it sorted :thumbsup:

[Gmanuk101]

I know, it's a strange one alright, when the card's software is in "Entertainment" Mode, it sends out a dedicated signal to the line out, and the line in seems to not like being used (I know not why). However when it's switched to "Audio Creation" Mode, both line in/out can be used to full effect.

The card I am using is http://en.wikipedia.org/wiki/Sound_Blaster_X-Fi (the Gamer version). It's a decent card, not as great as a StandDac of course :)