[Lewiscube]

Hi there, I'm Lewis

I recently got into the audio hobby and I'm happy to be a part of this community of experts and other people who share the love for the hobby. I haven't made an introduction on the forum for that as I am desperate to get help from people on this site asap!
Please read the following,

I have a fiio k3 2021 dac/amp which connects via usb-c to usb-a into my pc. When using the 3.5mm and 2.5mm outputs on my DAC/amp there is no interference at all.
I bought a pair of Mackie MR624 active speakers > https://www.gear4music.com/Recordin...-Powered-Studio-Monitor-Pair-with-Stands/2X1F
I use a 3.5mm to dual RCA adapter, priced at £11 and some standard RCA cables for L/R sound.

Before I get onto the issue heres the preface:

1 crucial part of understanding how I personally determined it was a ground loop problem was that when the dac was plugged into my ipad pro via usb-c to usb-c where the dac is powered by the ipad, all the nasty interference was gone so I knew it wasnt the cables or speakers.

I read the following two threads (you dont need to read these but here they are anyway) : https://www.head-fi.org/threads/how...picking-up-interference-from-computer.634541/
and https://www.head-fi.org/threads/computer-causing-hissing-in-yamaha-hs80ms.852093/#post-13535905

Forum no.2 was where I determined I had the same issues and decided to buy this which worked for someone else https://www.amazon.co.uk/AV-Link-Ground-Loop-Isolator/dp/B000NVWB9O

And it works! It completely removes the horrible interference from my computer. However it RUINS the low end, imaging and high end.. But at least I have diagnosed the problem!

So now I am at a loss. My two options (as far as I'm aware) are as follows:
1. Buy a new dac/amp that is powered externally through my extension cable and also splash £150-400 on it for endgame quality dac/amping. (I'd need one with a 2.5mm headphone balanced out or i'd have to buy a £30 2.5mm to 4.4mm balanced adapter which I am willing to do)
2. Buy a high quality ground loop isolator either for a usb port or for rca inputs+outputs

I'm glad to have a discussion but I would really like some suggestions as to what dac/amp to get OR what isolator to get (I cant find any isolators!)... As I am honestly clueless and as such not even sure option 1 would work. I'm presuming option 1 would work as my dac/amp isnt powered through the extension cable whereas dac's at that price range are?

Also I don't have any space to work with. I have a 6 extension cable in my room and thats it. So i can't power a dac + amp, it would need to be an all-in-one dac/amp.

Many thanks!
Lewis

 

[cinemakinoeye]

Assuming the hum is actually the result of a ground loop, there are two commonly used solutions to eliminate hum, either at the point of power connection using a ground/voltage filter (e.g. Ebtech Hum X Ground Line Voltage Filter) or between single-ended connections with a ground loop noise isolator (like you linked to above) between the audio connections (basically an isolation transformer in the circuit with possible effects on the audio quality). I have used both with success. If you can't easily swap out components to determine and correct the actual source of the group loop, these solutions offer a good approach. There are other solutions, but these two are the most common approaches.

EDIT: One more thing: If the source of the hum is being caused by a computer, then the solution would be to place a USB ground loop isolator between the computer and the DAC (e.g. iFi Audio iDefender).

 

[Lewiscube]

Assuming the hum is actually the result of a ground loop, there are two commonly used solutions to eliminate hum, either at the point of power connection using a ground/voltage filter (e.g. Ebtech Hum X Ground Line Voltage Filter) or between single-ended connections with a ground loop noise isolator (like you linked to above) between the audio connections (basically an isolation transformer in the circuit with possible effects on the audio quality). I have used both with success. If you can't easily swap out components to determine and correct the actual source of the group loop, these solutions offer a good approach. There are other solutions, but these two are the most common approaches.

EDIT: One more thing: If the source of the hum is being caused by a computer, then the solution would be to place a USB ground loop isolator between the computer and the DAC (e.g. iFi Audio iDefender).

Thanks for the reply. I have seen the iFi audio iDefender actually, would you believe this to be a product which would not impact sound quality? If so, I would probably get it. Saves me the hassle of buying more expensive equipment. The ground loop noise isolator I bought is fine for youtube + movies because the interference without it is unbearable (scratching, hissing, buzzing) but for music listening it is a big no no.

Edit: I have used my extension cable with only : active speakers + pc psu plugged into the extension cable. No monitor or wifi router attached. Still the same interference with such a setup. So it has to be the PC right? Furthermore, like I mentioned there is no interference when using the dac/amp on my iPad.

Edit 2: I also tried disconnecting all other usb devices, tried using the 3.5mm output on my motherboard (which just made the interference worse). The mouse moving causes the interference to get a lot worse, which from what I read in thread #1 which i linked in the OP is a direct result of a ground loop issue. Also , the power supply of my computer is 6 years old this month. Its 500W bronze rated from cooler master

 

[cinemakinoeye]

From what I have read,

So it has to be the PC right? Furthermore, like I mentioned there is no interference when using the dac/amp on my iPad.

If that is the case, it sounds like the source of the problem could very well be the PC. I have used the Ebtech Hum X Ground Line Voltage Filter in the past, and I've also used a ground loop noise isolator transformer, and they do work. When it comes to the iFi Audio iDefender I have no direct experience of it, but good thing that Amazon sells it with free returns, so if it does not work, you can return it. The iFi Audio iDefender gets mixed reviews, perhaps due to unreasonable expectations. The best way to determine if the USB is the issue is to try connecting a laptop not connected to power mains, but working off the battery, via USB. If that is silent, then yes, you have determined the USB connection is involved. This video (YouTube) goes through a detailed troubleshooting step that results in the use of the iFi Audio iDefender (this is neither a recommendation nor endorsement as I have not used it myself).

 

[Lewiscube]

and I've also used a ground loop noise isolator transformer, and they do work

Yeah, that was my experience with the one I linked from amazon. It really did work. It just sounds really bad sound-wise comparative to without using it (on the iPad).

but good thing that Amazon sells it with free returns, so if it does not work, you can return it

This is very true. I will need to buy a 5v power adapter for it since it doesn't come with one, but their "iPower 2" 5v power brick is £70!? Surely I can just buy a normal one for £10-20?

this is neither a recommendation nor endorsement as I have not used it myself

Completely understand that, I won't blame you at all if anything goes wrong.

This video (YouTube)

I watched this video before posting this reply. His interference noise is the exact same as mine. I will probably buy this product shortly and hope that it works. Just need to find a 5v power brick for the UK.

Thanks a lot for the quick reply , I really appreciate your help and the lengths you went through to help me. I will post an update in this thread and let others know if the ifi Defender worked for me or not. Thanks again!

 

[cinemakinoeye]

[…] I will need to buy a 5v power adapter for it since it doesn't come with one, but their "iPower 2" 5v power brick is £70!? Surely I can just buy a normal one for £10-20? […]

There is no reason you can’t use a standard USB 5V supply.

 

[Lewiscube]

Hello, I am making this post for anybody who comes happens to be reading this due to speaker interference issues.

Please refer to https://www.head-fi.org/threads/how...picking-up-interference-from-computer.634541/
and https://www.head-fi.org/threads/computer-causing-hissing-in-yamaha-hs80ms.852093/#post-13535905
as these threads helped me diagnose my ground loop problem and will hopefully help you diagnose too.

So my iDefender+ arrived and I bought the ifi iPower 2 due to the fact a lot of cheap solutions on amazon were variable voltage + variable amperage devices with so-so reviews. I opted for ifi's own power supply and I have only used the iDefender+ with said ifi psu. I have already learned that cheap solutions are not ideal... (The £8 rca loop isolator I mentioned above was awful for sound quality)

So for anybody reading this: yes, the iDefender+ helped solve my problem and there is no sound quality loss whatsoever.
If you are unsure if you have a ground loop problem, you can always buy a cheap one then return it as this will allow you to diagnose the problem before spending money on the iDefender.

I'm pleased the product works as intended and I am very happy there is no loss in perceivable sound quality. I've been listening for 30 minutes and the difference is night and day between the iDefender+ and the RCA ground loop isolator from av-link.

Again, thanks cinemakinoeye for replying to my thread so quickly.

 

[cinemakinoeye]

[…] for anybody reading this: yes, the iDefender+ helped solve my problem and there is no sound quality loss whatsoever.
If you are unsure if you have a ground loop problem, you can always buy a cheap one then return it as this will allow you to diagnose the problem before spending money on the iDefender […]

It’s good to know it worked for you, I’m always suspicious of products that promise solutions without some first hand or trustworthy second hand evidence to back up the claim.

 

[fortunate son]

We hear what we hear, don't we? I have tried each of the solutions mentioned in this forum to eliminate ground loop noise when using my Decware ZTM3 headphone amp. But, the only product I have found that worked without appreciably degrading sound quality was this: Jensen Iso-Max CI-2RR RCA Stereo Line Input Isolator Hum Eliminator

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