RFI from PC's WiFi Card

[koalapear]

Hey guys, I just finished building my Crack+Speedball and it all seems to be working great except that after I installed the Speedball I have noticed RFI noise that corresponds to internet activity on my PC. I didn't notice it before the Speedball install but it could have been there and I didn't notice as I was too busy listening to music. I also think that the noise could be more apparent since I think the Crack is louder with the Speedball (I also notice a noise floor at about 12 o'clock instead of about 2 o'clock but I figured that was just because that Crack is louder all round). I was wondering if the amp were at fault would there still be RFI with no source plugged in? I ask because when I unplug my DAC (just using the line out on my E10 right now as I wait for my Modi 2 Uber to ship) the noise goes away. I'll post pictures  if needed. Thanks in advance!

EDIT: I think it might be my DAC's USB cable. I plugged the DAC into my laptop with a short USB cable rather than the 10ft one I use with my PC and I don't have and issue! I guess I'll be going with optical once I get my Modi.

[Paul Birkeland]

There can be other sources of noise from computers that will travel down USB cables/analog audio cables to pollute the amp. 

On several computers that I have owned in the past, I could hear the CPU churning away through my headphones under certain conditions, and the spinning motors in the hard drives were also quite audible. 

Going to an optical connection should eliminate all of this. 

You are also correct, the gain of the Crack is bumped up as a consequence of installing the Speedball.

-PB

[koalapear]

Thanks for the insight! After some more troubleshooting it seems to be my motherboard's USB is just noisy (which is disappointing as I have an ASUS Sabertooth Z87 which is not exactly a cheap motherboard). When I plug my DAC into my laptop everything is dead silent and there is no audible noise floor. Definitely going to switch to optical if the issue persists with my new DAC.

[Paul Birkeland]

It's probably not the motherboard, but rather the switching power supply used to power it.

-PB