Noise with Computers, USB DACs, and Powerline Ethernet Kits

[rguenther]

Thanks for your quick response.
No, the noise is present as long as the laptop sits right beside it. Whether the laptop is battery powered or plugged into power doesn't affect the crackling.

[Paul Birkeland]

If you turn the laptop to airplane mode, does the noise go away?

[rguenther]

Yes it does!

[Paul Birkeland]

I would recommend purchasing a 0.1uF X7R capacitor (leaded, not a surface mount/smt).  Solder that between the ground shell of the red RCA jack and terminal 22.  That may or may not solve the problem, but it's a cheap experiment to try.

[rguenther]

Assuming I got the right part: it didn't solve the noise.

Now, with the Crack sitting besides the non-airplane-mode laptop,
a) when no RCA jacks are plugged in: audible hum on both channels, increases when volume is turned up. Masks the initial left channel crackling.
b) with RCA jacks plugged in (either to a cellphone or another grounded DAC): the audible hum mentioned above is gone - but the left channel crackling remains

The good news is: just 50-60cm of distance between laptop and Crack will reduce the left-channel-crackle to almost nothing. I'll just re-arrange my setup and take the capacitator out again :-)



PS I can't seem to insert the attached image. The capacitator reading is 104KH 250VMY. It's attached to terminal 22 and the ground lug of the red RCA jack.

[Paul Birkeland]

That is not an X7R cap, and yes, it may indeed matter.

[JoshuaA]

I just wanted to chime in that:

• Crack baseline: All sorts of CPU noise from ground loop from my DAC (SMSL D300) clearly audible at around 30-40% on the volume knob. Unplugging USB cable from DAC would remove all noise.
• Crack + Speedball: Would hear the same CPU noise at ~20% volume. Was driving me nuts!
• Crack + Speedball + anti-phase STTH2R06: Same CPU noise barely audible at 100% volume.
  

Given that I listen at 15-25% (depending on album), I'm very happy to report that thanks to the mod, I am listening to pure silence in between tracks and silent moments!

Thanks for making this a sticky, and the easy $1.24 + 5 minute fix!

[dittopizza]

Worked perfectly on my Crackatwoa!

I have an Audiolab M-Dac connected to my PC via USB and prior to this, there was noise leak at 0% volume (could still hear music), an audible background noise past 75% volume and moving my mouse on the screen caused background noise as well.

Now 0% volume silences all sound, volume knob turned to 100% has no background noise, and no more background noises with my mouse.

Was getting ready to replace my DAC prior to finding this fix.

Paid $2.02 at Digikey for two STTH2R06.

Thank you!

[Cowwe]

Hello,
I want to add this modification to my Crack, since I get a lot of loud noise through usb whenever my pc is working on some demanding program.
I've been looking for the STTH2R06 but I can't find them around my area and the shipping costs are pretty high. I've bought a handful of 1N4007 instead since they were mentioned here before.
Before I proceed with the mod I just wanted to ask for confirmation that these diodes would work fine, since looking them up they seem to measure 1A (I'm rather clueless when it comes to these components). Am I good to go?

[Paul Birkeland]

They have a sufficient surge rating to handle the duty there in case of failure, so go ahead and use them.

[Jdjung]

Just wanted people to know this worked perfect for my SEX kit. In terms of how to do it, just disconnect the skinny wire connected to E on the top left corner (Look at page 25 of your Terminal Identification photo), you don't even need to cut the wire, just unsolder the wire, twist the diodes in opposite directions together making sure it doesn't short on anything else and "voila" no noise at all if you have it connected to your DAC.

[mchuckp]

I would absolutely not use surface mount diodes in this application.

Order 1N4001, 1N4002, 1N4003, 1N4004, 1N4005, 1N4006, 1N4007, UF4001/2/3/4/5/6/7.

Any reason to pick one over the other or all going to do the exact same job?

[Paul Birkeland]

They are all about the same in this application.

[tipatina]

I have these noises with a new MacBook>Topping D50 III that otherwise sounds great. I'm using it in a system with a Smash preamp. Interestingly, when I replace the Smash with Akitika SS preamp or DeHavilland Ultraverve-no noise. When I use the Smash with Audioquest Dragonfly DAC noise is gone. Ill try the mod. Are there different USB grounding issues between DACs?

[tipatina]

I did the mod on my Smash-UP. See attached photo. So far so good with sound-much better. In the Smash the distance between the ground/earth on the IEC and the chasis ground is longer and the twisted leads were barely long enough.
Basic question: In testing continuity between the IEC ground and chasis ground-no continuity. There is continuity between each lead and its attachment so I know the joints are at least conductive. Do the diodes somehow prevent continuity as tested by multimeter beep?