[Dinglehoser]

I'm just at wit's end. So long as there is an electrical connection between my computer and amp, I get this infernal intermittent interference-like sound from my speakers regardless of what volume my amp is set at (even all the way down). I've never had any problem like it. Here are the players:

HTPC with onboard coax, optical SPDIF (motherboard: DFI Lanparty TR4S-P45 JR with super noisy digital PWMs)
Rega Planet CDP
iBasso D3 USB DAC
Zhaolu DAC without USB
Jolida 102B amp (tube)
Paradigm Studio 20 v3 speakers

All plugged into the same outlet through an APC C10.

The noise I'm talking about is not unlike the swishing, squeaking, intermittent electronic noise you'll often hear out of cheap onboard analog outs. It does not sound like a ground loop hum. Here are my findings.

HTPC optical out -> Zhaolu -> amp -> speakers: No noise, not a peep.
HTPC coaxial out -> Zhaolu -> amp -> speakers: Noise.
HTPC USB -> iBasso D3 -> amp -> speakers: Noise.

HTPC optical out -> Zhaolu -> headphones: No noise.
HTPC coaxial out -> Zhaolu -> headphones: No noise.
HTPC USB -> iBasso D3 -> headphones: No noise

Rega Planet analog out -> amp -> speakers: No noise.
Rega Planet coaxial out -> Zhaolu -> amp -> speakers: No noise.

And for ****s and giggles ...
HTPC optical out -> Zhaolu -> iBasso D3 -> Macbook Pro -> amp -> speakers: No freaking noise.

As I mentioned before, it seems related to having an actual electrical connection between the amp and the computer. I've tried different interconnects, different power cables, everything - still that same infernal electronic noise if I use anything but optical SPDIF. Remember, they're all plugged into the same outlet via a pretty good power filter, and the noise I'm talking about does not change in volume regardless of how high the amp is turned up. It is not subtle, and is extremely annoying.

Any ideas?

 

[obobskivich]

well, TOSlink seems to have solved it (so why fight that?)

as far as the cause, I'd venture: ground loop, or some other nasties

if it was onboard analog -> joojoo, then yeah, you could have a legitimate case for "the computer is jacking my sound", but when its ANY electrical connection, you've either got one of the crappiest PSUs on the planet (care to tell us about it?) or a nice little groundloop (although that APC *should* solve that, that doesn't gurantee a thing)

 

[Dinglehoser]

The reason why I'm up in arms is because I want to run my computer's output through coax. The reason for *that* is that my TV has only optical out, and I want to route its sound through my DAC. I suppose I could get one of those sketchy optical to coax converter boxes, but the OCD part of me wants to fix the problem at its source. Problem is, I have no idea what said source is.

The PSU in question is a Seasonic-built Antec 430W unit. Nowhere near the world's crappiest. All the symptoms except the quality of the noise point to a ground loop. It's like a combining a nasty ground loop and copious amounts of EMI/RFI into one infuriating package. Gah.

 

[obobskivich]

Quote:

Originally Posted by Dinglehoser /img/forum/go_quote.gif The reason why I'm up in arms is because I want to run my computer's output through coax. The reason for *that* is that my TV has only optical out, and I want to route its sound through my DAC. I suppose I could get one of those sketchy optical to coax converter boxes, but the OCD part of me wants to fix the problem at its source. Problem is, I have no idea what said source is. The PSU in question is a Seasonic-built Antec 430W unit. Nowhere near the world's crappiest. All the symptoms except the quality of the noise point to a ground loop. It's like a combining a nasty ground loop and copious amounts of EMI/RFI into one infuriating package. Gah.

theres nothing at all wrong with an optical to coax converter (sketchy? how-so? its just a S/PDIF TxRx in a box)

honestly, I'm thinking ground-loop, try another power strip perhaps, how about lines coming into or out of the PC, that could be creating a groundloop? (that aren't powered off this APC...)

 

[Dinglehoser]

Quote:

Originally Posted by obobskivich /img/forum/go_quote.gif theres nothing at all wrong with an optical to coax converter (sketchy? how-so? its just a S/PDIF TxRx in a box) honestly, I'm thinking ground-loop, try another power strip perhaps, how about lines coming into or out of the PC, that could be creating a groundloop? (that aren't powered off this APC...)

Sketch in terms of build quality. The ones I've seen look like they were built by Fisher Price. I might try one anyway.

The more I think about it, the more I'm inclined to agree with you. I've tried three different types of powerstrips, though, and absolutely everything that touches the entire setup is plugged into the same power strip. I might try floating the amp's ground using a cheater plug and see if that helps.

 

[obobskivich]

Quote:

Originally Posted by Dinglehoser /img/forum/go_quote.gif Sketch in terms of build quality. The ones I've seen look like they were built by Fisher Price. I might try one anyway. The more I think about it, the more I'm inclined to agree with you. I've tried three different types of powerstrips, though, and absolutely everything that touches the entire setup is plugged into the same power strip. I might try floating the amp's ground using a cheater plug and see if that helps.

so your entire network sits on this power strip? how about your cable company's equipment? or, if no cable, your entire DSS system?

and if you want over-the-top quality on a coax/TOS box:
M-AUDIO - CO2 - Coaxial/Optical Bi-Directional Converter

 

[Dinglehoser]

Quote:

Originally Posted by obobskivich /img/forum/go_quote.gif so your entire network sits on this power strip? how about your cable company's equipment? or, if no cable, your entire DSS system? and if you want over-the-top quality on a coax/TOS box: M-AUDIO - CO2 - Coaxial/Optical Bi-Directional Converter

Yes. The cable modem, router, wired network devices (including my NAS, PS3, and XBox360), and cable box are connected to the same power strip. The C10 is pretty beefy.

Thanks for the link. I've always like M-Audio stuff ... and that piece looks like it was built to survive the apocalypse. At $80, though, I think I might take my chances with the sweatshop labor-produced plastic box I found on monoprice and save $60. If it works, it works ...

 

[obobskivich]

Quote:

Originally Posted by Dinglehoser /img/forum/go_quote.gif Yes. The cable modem, router, wired network devices (including my NAS, PS3, and XBox360), and cable box are connected to the same power strip. The C10 is pretty beefy. Thanks for the link. I've always like M-Audio stuff ... and that piece looks like it was built to survive the apocalypse. At $80, though, I think I might take my chances with the sweatshop labor-produced plastic box I found on monoprice and save $60. If it works, it works ...

honestly the #2 thing I'd be wondering about, given how much crap you've got on a single powerstrip (I would NEVER load a powerstrip up like that, I don't care if its a Monster Pro AVS with AVR and enough caps to make some amps look bad

), you might be running "voltage low" on ye olde PC, and ye olde Antec PSU probably has crap for voltage fluctuation tolerance

also, are you grounding your coaxial in service through this thing? try pulling that out + unplugging some crap, see what that does for you

 

[Dinglehoser]

Interesting points. I've never gone above 40% load according to the LED readout on the C10, but something to consider. I might try unplugging everything except the computer, TV, and amp and seeing what happens. Lots of things to try now ...

 

[milhouse6]

Probably won't be helpful but for what it's worth...

Couple of years back I spent about a month fighting with an M-Audio Fasttrack USB for a similar problem until I figured out it was as stupid as interference from my 900mhz phone base. Killed the power to the phone by accident one day and presto. The base wasn't even anywhere near my computer desk.

 

[Dinglehoser]

Short answer: ground loop.
Fix: cheater plug.

This is the quietest my Jolida's ever been. Damn the ground!

 

[obobskivich]

Quote:

Originally Posted by Dinglehoser /img/forum/go_quote.gif Short answer: ground loop. Fix: cheater plug.

figures.

glad you fixed it

now I have to ask: you have the entire power strip on a cheater plug? or just the amp?

 

[roker]

thanks for the info guys

I'm buying a cheater plug for my setup because I'd really like to keep my fubar II

I'll post my results later . . . (like when I get my self over to a store to buy them)

 

[Uncle Erik]

Quote:

Originally Posted by milhouse6 /img/forum/go_quote.gif Probably won't be helpful but for what it's worth... Couple of years back I spent about a month fighting with an M-Audio Fasttrack USB for a similar problem until I figured out it was as stupid as interference from my 900mhz phone base. Killed the power to the phone by accident one day and presto. The base wasn't even anywhere near my computer desk.

Be sure to consider RFI interference like this. Cordless phones, cell phones, dimmer switches, AC motors, fluorescent lights, nearby radio transmitters, and much else.

This sounds more like RFI to me than a ground loop.

 

[CDBacklash]

x2 on the RFI. I find that groundloops are not independant of volume, but that some RFI is (could just be me).