Noise interference.

Dempsey22 · 23 Aug 2018 at 17:33

Okay so I got my new speakers yesterday. JBL LSR305s.

I have them connected like the following.

PC > Modi 2 > Magni 3 > LSRs

I have an annoying noise coming from both speakers that gets more high pitched when CPU is under load. If i disconnect USB that connects the Modi 2 to PC then sound is gone.

What is the most affordable way to solve this?

Optical out isn't an option as I dont have the Modi 2 Uber.

Thanks

Marsman · 23 Aug 2018 at 18:29

Hmm. This could be an issue, as it would seem you have electrically noisy USB.

Do you hear the same noise if using headphones with the Magni?

EsaT · 23 Aug 2018 at 18:33

You could try USB isolator.

Dempsey22 · 23 Aug 2018 at 20:28

Marsman said:
Hmm. This could be an issue, as it would seem you have electrically noisy USB.

Do you hear the same noise if using headphones with the Magni?

EsaT said:
You could try USB isolator.

Im at work till tomorrow so will check then but I cant remember if it was with the headphones.

When I use my headset and mic through the back audio ports I did get same noise through that headset. It only went away when I plugged them into the front audio.

Ill try use the front USB port for the Modi 2 and see if it makes a difference.

Schiit recommended a powered usb hub or else their Schiit Wyrd but for 110 quid its abit steep.

PapaLazaru · 23 Aug 2018 at 22:37

Are you using a USB directly connected to the motherboard?

*edit* Sorry did not read.

Are you plugging it into a USB 3? If so, try one of the old ones. My Marantz HD-DAC1 does not like USB3 either.

Dempsey22 · 24 Aug 2018 at 02:32

PapaLazaru said:
Are you using a USB directly connected to the motherboard?

*edit* Sorry did not read.

Are you plugging it into a USB 3? If so, try one of the old ones. My Marantz HD-DAC1 does not like USB3 either.

Was in USB 3 but switched to USB 2 made no difference.

I tried all remaining USB ports and same.

Next option is to try an external powered USB.

Mick-1965 · 24 Aug 2018 at 15:13

Sounds like an earth loop problem.
Your pc is connected to the earth via its own 3 pin plug.
You've just added a powered speaker at the end of your audio chain which also has a 3 pin plug directly to the mains which creates a loop.
So now your PC can now try and earth through the loop via your speaker at the end causing noise on the earth which is what your speakers are picking up.
You can test to see if it is a earth loop problem by plugging the speakers into an extension lead, but in the plug of the extension lead temporarily remove the earth wire.
If the noise stops take steps to break the earth loop. As above a usb isolator or a RCA phono isolator between the magni and speakers.

Under no circumstances run the speakers permanently from the extension lead with out the earth.

Dempsey22 · 24 Aug 2018 at 16:43

Mick-1965 said:
Sounds like an earth loop problem.
Your pc is connected to the earth via its own 3 pin plug.
You've just added a powered speaker at the end of your audio chain which also has a 3 pin plug directly to the mains which creates a loop.
So now your PC can now try and earth through the loop via your speaker at the end causing noise on the earth which is what your speakers are picking up.
You can test to see if it is a earth loop problem by plugging the speakers into an extension lead, but in the plug of the extension lead temporarily remove the earth wire.
If the noise stops take steps to break the earth loop. As above a usb isolator or a RCA phono isolator between the magni and speakers.

Under no circumstances run the speakers permanently from the extension lead with out the earth.

Absolutely spot on. I had a 3 pin to 2 pin adapter lying next to the computer. Just popped that onto extension lead and plugged it into socket. Powered back on speaker and no noise from it whatsoever

What will be the easiest option for both speakers? The USB isolator or the RCA isolator? I seen the USB ones are 1500v and 3000kv. Which would I need ?

Mick-1965 · 24 Aug 2018 at 17:03

The isolator should simply isolate one side of the loop from the other. Other words breaking the earth loop.
As long as it does this either should suffice.

Rca phono isolators seem to be your cheapest option.

Dempsey22 · 25 Aug 2018 at 12:56

Mick-1965 said:
The isolator should simply isolate one side of the loop from the other. Other words breaking the earth loop.
As long as it does this either should suffice.

Rca phono isolators seem to be your cheapest option.

Ordered an RCA isolator. Will be with me next week.

Thanks again for your help.

Vinnylupo · 8 Oct 2018 at 10:49

Dempsey22 said:
Ordered an RCA isolator. Will be with me next week.

Thanks again for your help.

Really sorry to drag up an old thread, i'm having almost the exact same issue and just wanted to know if buying an RCA isolator fixed the issue.
Cheers

Dempsey22 · 8 Oct 2018 at 12:50

Vinnylupo said:
Really sorry to drag up an old thread, i'm having almost the exact same issue and just wanted to know if buying an RCA isolator fixed the issue.
Cheers

It did indeed. No issues now whatsoever

Vinnylupo · 8 Oct 2018 at 12:51

Best, thank you for responding.