EMF (?) interference with S.E.X. 2.0

[denti alligator]

I'm using my amp exclusively for headphones and I notice some nasty interference when playing files from my PC. It's a high pitched wheezing that goes in and out. It's pretty quiet, but noticeable in between tracks and with quiet music.

I thought it might be the wifi, but have ruled that out. It's only when the CPU is going. So when I start a track it starts up; when I stop a track it stops. When I open a browser on the PC, it starts up, etc.

I've put copper tape shielding on the inside of the PC case and the SEX amp. And I've tried moving the amp further away (it's now about 6 feet away). No improvement.

Any thoughts on a next step? Some more robust EMI shielding for the PC?

[caffeinator]

Hi denti-alligator,

When you say "only when the CPU is running," do you mean when the PC is running, or the processor itself?  Are you running the files from a CD in the PC drive, from the hard drive of the PC, or from memory or a SSD?

TIA,

david

[Paul Birkeland]

This is just the noise of your PC doing its work.  It will go away if you add a DAC and cable the two together with Toslink.

[denti alligator]

I should have specified:

I am running the PC to an external DAC using USB.

I mean that the noise occurs when the CPU is higher that simply its idle mode. The tracks are on a NAS, being transmitted over wifi. But I tested with a track on the PC and it was the same.

I'm using the Stereomour as a source selector, by the way. I just tested the Stereomour on its own. Putting my ear up to the speakers and turning the volume all the way up I can hear the same sound. Not really audible at normal volume and listening distance.

[denti alligator]

It's definitely the PC. My toptop doesn't produce the same sound. I've ordered a USB filter. Hopefully this will help. I'll report back.

[Paul Birkeland]

order a toslink cable (and USB to toslink adapter if you don't have an available toslink port).

-PB

[denti alligator]

order a toslink cable (and USB to toslink adapter if you don't have an available toslink port).

-PB

I can't do DSD over toslink, unfortunately. My DAC sounds pretty sweet with DSD, so that's what I'm aiming for.

[physicsmajor]

For the record, this is (or at least, can be) a thing.  It's an intermittent scratchy/whining sound much like coil whine from some laptops, or how early 3G phones could sometimes interact with wireless PA systems or speakerphones.

In my case, it's definitely not correlated with the attached computer's activity.  Only present at a low level so I dealt with it for a while.

In the end I did track it down to other wireless devices - specifically, bluetooth and Wi-Fi.  This first showed up in my 2.1 model when I replaced a B/G router with a N-capable one.  My amp is on my desk, the router is almost directly under it on a shelf.  Verified further by doing some heavy wireless streaming next door.  However, finally figuring out the source let me reduce it greatly by moving/reorienting the router.

Your mileage may vary, but that's my experience.

[denti alligator]

It's definitely coming from the computer. And it's not the wifi.

I got an ifi iPurifier for the USB. Doesn't help! So I'm sending that back. I've ordered a more robust USB cable, which I'll try next. After that I have no clue what to do.

When I play from my laptop I don't get the interference, but my laptop doesn't have the power to do DSD, and anyway, it's my laptop. I need it for other stuff.

[denti alligator]

I'm returning the motherboard. Hopefully that will solve this.

[denti alligator]

After trying a ton of other things, including switching out the motherboard and power supply, etc. etc, I finally solved this by putting the 3-prong plug of the S.E.X. into a 2-prong plug. Is this safe? Should I attach the ground somewhere.

[Paul Birkeland]

After trying a ton of other things, including switching out the motherboard and power supply, etc. etc, I finally solved this by putting the 3-prong plug of the S.E.X. into a 2-prong plug. Is this safe? Should I attach the ground somewhere.

https://en.wikipedia.org/wiki/Cheater_plug#Safety

[Jamier]

My first SET amp was (is, I still have it) a Triode Corp TRV A 300 SE. It actually came with an adapter that allowed disconnection of the ground. I put it in a ziplock with a note that says " never use this!" It is a great little amp. It's the amp that changed my audio life.

Jamie

[denti alligator]

https://en.wikipedia.org/wiki/Cheater_plug#Safety

So what are my options for removing the ground loop?

[Jamier]

Sam, is the computer on the same circuit as the rest of your system, including the SEX? I have some components that make all kinds of noise if they are not all powered by the same circuit ( on
the same circuit with respect to the home's wiring, you know, on the same breaker).
Jamie