[SOLVED] Ground loop between grounded Hypex NC400 DIY amp and ungrounded Denon 3700X

[JayGilb]

Okay, the new thing is the popping and clicking that even persists when disconnecting the hypex completely. I tried about everything: BIOS settings, energy management adjustments, latency analysis...

I will try out some different HDMI cables and ports tomorrow and try out toslink for my TV. Since the pop almost always occurs when moving a window or switching a tab on PC I guess it's either something TV, GPU oder CPU related. I'd love to increase sample size of HDMI audio but I can't find some settings to adjust this like with an USB driver of an interface.
Funnily enough the panning of the click sound is completely random. Sometimes left, center, right or something in between.

Sounds like a ground loop and your GPU is causing noise that is appearing on your audio.
When your ground reference level is shifted from 0 volts, low level signals that were once hidden below threshold levels suddenly become audible.

 

[Lambda]

Sounds like a ground loop and your GPU is causing noise that is appearing on your audio.
When your ground reference level is shifted from 0 volts, low level signals that were once hidden below threshold levels suddenly become audible.

I not so sure about this.
to me it sounds like some digital problem?
Maybe buffer over/under run or some transmission error
If it is caused by transmission error/loss this could be do to a ground loop or EMI but the digital signals are all differential...

Try a different HDMI cable?
put the PC right next to the TV
try connecting the PC only to the TV ans see if the problem persists.

 

[anphex]

The fastest thing I could try out now was to plug the HDMI cable from the GPU directly into the TV.
Surprise, the issue persists. So the AVR can completely be ruled out by now. It's a matter of the PC, GPU or HDMI cable.

 

[anphex]

I tried it on my sleeping room tv with another HDMI cable. Exakt same issue. So cable isn't the cause either.
I remember it started happening when I did my mainboard upgrade but the GPU is still the same... I could think of something PCI Express port related though.

Edit: Finally I think I found a hint. I looked closely at the clock behaviour of my GPU with Nvidia Performance Overlay. Eveytime a pop appears about a second later the performance monitor shows that the GPU has "jumped" to an higher clock, usually the maximum clock. When it's about 250 Mhz everything is fine, but when it jumps to 1900 Mhz (for no apparent reason or when I do something with a GPU accelerated window program) one second before this the pop happens. So it is very obvious it's the clock adjustment of the GPU!

 

[anphex]

FFS, I FOUND THE ISSUE AND FIX
I AM ABOUT TO SEND NVIDIA/EVGA A BILL FOR THIS WASTE OF TIME.

Like I already suspected, it's the switching from the low to high clock state that causes a small audbile *pop*. I am 100% sure this is technically bullshit and shouldn't happen at all but here we are. When choosing "prefer maximum performance" in the Nvidia Control Panel below "3D settings" it stays at the maximum clock. It works now! No more pops! But my power draw went up by 100 Watt in Idle which is a big nono.
I will contact NVIDA/EVGA about this.

 

[KMO]

I'm not helping on the original issue, but I'm hopping in to ask about the Cordial CFU-MC cable you mentioned earlier. It seems like an easy purchase where I am, and I've seen others happy with it and suggesting that it has two signal conductors, but the construction diagram on their site that you posted earlier doesn't look promising.

Did you manage to confirm their construction? Is pin 3 running down the shield or a signal wire inside the shield?

 

[anphex]

I'm not helping on the original issue, but I'm hopping in to ask about the Cordial CFU-MC cable you mentioned earlier. It seems like an easy purchase where I am, and I've seen others happy with it and suggesting that it has two signal conductors, but the construction diagram on their site that you posted earlier doesn't look promising.

Did you manage to confirm their construction? Is pin 3 running down the shield or a signal wire inside the shield?

If you were asking me: I didn't receive this cable since I cancelled the order right after my problem was solved by cutting XLR pin 1.

 

[KMO]

If you were asking me: I didn't receive this cable since I cancelled the order right after my problem was solved by cutting XLR pin 1.

Oh, I thought that was the cable you were originally having noise problems with:

I have to use an RCA-XLR cable, this one to be specific: https://www.cordial-cables.com/de/produkte/cfu-mc

Now I have some ground hiss the whole time in all speakers

 

[anphex]

Oh, I thought that was the cable you were originally having noise problems with:

Haha oh sorry I confused it with the Monoprice cable. Yes I actually had the cordial and I am still using it right now with the cut wire.
Later this day I will upload a picture for you!

 

[BoredErica]

Computer noises suck. I have them with my old setup I'm about to replace. When I alt tab to a game I hear loud weird PC interference noises which vary based on what's happening on the computer. Not quite your situation of course. I hope moving to all balanced will alleviate some of those issues.

 

[Lambda]

Computer noises suck. I have them with my old setup I'm about to replace. When I alt tab to a game I hear loud weird PC interference noises which vary based on what's happening on the computer. Not quite your situation of course. I hope moving to all balanced will alleviate some of those issues.

How is the computer connected in your cases USB DAC or also HDMI.
Is it an self configured PC or from an big OEM like DELL,HP,Lenovo..?

 

[BoredErica]

How is the computer connected in your cases USB DAC or also HDMI.
Is it an self configured PC or from an big OEM like DELL,HP,Lenovo..?

Computer -> USB Dac/Amp -> Ground Loop Isolator (Kills the noises) -> Powered Speakers

 

[Lambda]

Computer -> USB Dac/Amp -> Ground Loop Isolator (Kills the noises) -> Powered Speakers

I would have tried to get rid of the noise on the USB side.
A (Active) Hub can already help a lot especially if it has grounding.

Do your powered speakers have an Balanced input? if so i would consider using it even if the source is not balanced.
Lots of information abut that in in this thread.

 

[BoredErica]

I would have tried to get rid of the noise on the USB side.
A (Active) Hub can already help a lot especially if it has grounding.

Do your powered speakers have an Balanced input? if so i would consider using it even if the source is not balanced.
Lots of information abut that in in this thread.

Should be moving to a new setup soon that is balanced from start to finish. Should automatically fix all the problems, no?
If not I'll consider the hub.

 

[anphex]

I'm not helping on the original issue, but I'm hopping in to ask about the Cordial CFU-MC cable you mentioned earlier. It seems like an easy purchase where I am, and I've seen others happy with it and suggesting that it has two signal conductors, but the construction diagram on their site that you posted earlier doesn't look promising.

Did you manage to confirm their construction? Is pin 3 running down the shield or a signal wire inside the shield?

Posting this here for the convenience of others too. This is the CORDIAL RCA XLR cable I am currently using with the cut pin 1 "mod". That is completely noise free. I connected the signal ground connector with a screw of one of the Hypex chassis to still have grounding on the AVR somehow. Don't know it this makes sense or improves anything but I had no troubles so far and it felt like a good idea.

 

[KMO]

Posting this here for the convenience of others too. This is the CORDIAL RCA XLR cable I am currently using with the cut pin 1 "mod". That is completely noise free. I connected the signal ground connector with a screw of one of the Hypex chassis to still have grounding on the AVR somehow. Don't know it this makes sense or improves anything but I had no troubles so far and it felt like a good idea.

Thanks!

Struggling a bit to visualise, but it looks like that is a twin-conductor cable, as I thought, and that was giving me hope.

But both conductors are going to pin 2, and the shield is going to pin 3, and originally pin 1. (Right?) So that does agree with the "single-conductor" wiring diagram Cordial supplied:

But what we apparently should be using is this:

Second version keeps earth currents away from the signal path as much as possible, reducing how much voltage perturbation earthing currents cause.

Is the RCA plug openable or is it molded? If one hypothetically wanted to rewire the whole thing?

Easier to buy one made correctly in the first place, of course.

 

[anphex]

Yes, it's actually openable. So, I gotchu:

 

[Lambda]

Strange design decisions from Cordial right there.

1. Why did thy uses Twisted pair in this cases.
2. Why did they doubled up the signal conductor
3. If they have a 3 conductor calculable to start with why don’t they do it the proper way and make the GND to negative connection on the CRA side.

 

[anphex]

Now we need someone with the Monoprice cable to open it up and make some pictures. You guys are giving me a bad feeling about my cable haha.

 

[KMO]

Yes, it's actually openable. So, I gotchu:

Neat. Now, I'm not sure there actually is anything better than this available in Europe. I'm not sure I can even find anything else that definitely has a twin conductors.

That Cordial lead at least gives you the parts to make a good cable fairly economically, and it may work adequately as-is...

Strange design decisions from Cordial right there.

1. Why did thy uses Twisted pair in this cases.

Possibly because that's what they have/make? They don't really produce many single-signal cables apart from video. Not much call for them in professional wiring. So it's probably the most sensible option from their range.

Bulk Cables

www.cordial-cables.com

But not then wiring it better is pretty unforgivable.