Help !! There is a noise problem.

[Pigeon]

Hello! I can't speak English well, so I'm only watching ASR and writing for the first time.

Currently I am configuring (pc,tablet pc)> svs sb-1000(sub)> genelec 8030cp

Until I bought a new dac, I tried to connect (pc, tablet pc)> 3.5 to 2rca> sb-1000> rca to xlr 2 lines> 8030c.

However, when the 3.5 connector of the 3.5 to 2rca cable is not connected anywhere and when connected to a PC, the 8030c makes a lot of noise.

On the other hand, the noise disappears when the 3.5 connector of the 3.5 to 2rca cable is connected to the tablet, and the noise disappears when the 3.5 to 2rca cable is removed from the subwoofer. (Only 8030 connected to subwoofer)

With 3.5 to 2xlr cable, it is directly connected to the PC except the subwoofer, so there is no noise.

If the subwoofer, cable, or connector is the cause, I do not understand that the noise disappears when connected to a tablet PC.

If the pc is the cause, I don't understand that the noise disappears when connected directly to the 8030. How to fix it??

 

[pozz]

Hi and welcome.

You have a ground loop. This is common when using single-ended (RCA) connections.

To break it use an isolation transformer or change equipment, for example adding a DAC.

Easy way to avoid this issue is to used balanced (XLR) connections throughout your system.

 

[twsecrest]

Hello! I can't speak English well, so I'm only watching ASR and writing for the first time.
Currently I am configuring (pc,tablet pc)> SVS sb-1000(sub)> Genelec 8030cp
Until I bought a new DAC, I tried to connect (pc, tablet pc)> 3.5 to 2rca> sb-1000> RCA to XLR 2 lines> 8030c.
However, when the 3.5 connector of the 3.5 to 2rca cable is not connected anywhere and when connected to a PC, the 8030c makes a lot of noise.
On the other hand, the noise disappears when the 3.5 connector of the 3.5 to 2rca cable is connected to the tablet, and the noise disappears when the 3.5 to 2rca cable is removed from the subwoofer. (Only 8030 connected to subwoofer)
With 3.5 to 2xlr cable, it is directly connected to the PC except the subwoofer, so there is no noise.
If the subwoofer, cable, or connector is the cause, I do not understand that the noise disappears when connected to a tablet PC.
If the pc is the cause, I don't understand that the noise disappears when connected directly to the 8030. How to fix it??

Try using separate surge protectors, like one for the PC, one for the Sub and one for the 8030C.

 

[Pigeon]

Hi and welcome.

You have a ground loop. This is common when using single-ended (RCA) connections.

To break it use an isolation transformer or change equipment, for example adding a DAC.

Easy way to avoid this issue is to used balanced (XLR) connections throughout your system.

Thank you for answer!

I ordered the topping e30 dac.

The sub-out stage is rca, so it seems difficult to have a balanced system.

The noise should disappear...

 

[Pigeon]

Try using separate surge protectors, like one for the PC, one for the Sub and one for the 8030C.

Thank you for answer!

Even if I blocked the ground terminal, I tried to separate it with a power strip, but there is still noise.

I hope this is solved by additional dac.

 

[AnalogSteph]

The ground loop is between the PC and the Genelecs. It is the connection between the sub and these that you would have to tackle.

I would suggest either of the following options:
1. Make custom RCA -> XLR cables with only two connections: Signal --> hot (pin 2) and Ground --> cold (pin 3).
or
2. 2x RCA --> 1/4" TS cable --> Behringer HD400 --> 2x 1/4" TRS to XLR (balanced) cable.

Unfortunately, when using this with a floating signal source like the tablet, you could get a new problem. With the sub floating, either the HD400 or the 8030 input stage may be subjected to considerable common-mode input voltage due to capacitive leakage across the sub's power transformer, leading to hum intrusion. In this case, an additional earth connection should be provided at the sub - not sure where best to attach it in this case. That, unfortunately, would introduce a ground loop between the PC and the sub!

So I'm afraid you may have to decide between either the PC or the tablet.

The E30 is unlikely to improve anything, I don't think it provides any galvanic isolation (which would be another possible solution). USB isolators may be worth researching, but no idea how well a hi-res DAC would work with these (basic ones are generally restricted to USB 1.1 data rates).

A wild mix of consumer audio (unbalanced, floating) and pro audio (balanced, grounded) as seen here is generally problematic and thus to be avoided. As adding balanced outputs to a PC is relatively inexpensive compared to the rest (sub-€200 for a decent audio interface, 200-300 for a DAC) and off-the-shelf 3.5 mm to 2x XLR cables should get the job done for a tablet, I'd suggest reconsidering your priorities WRT the sub. Maybe a JBL 310S instead?

 

[Chrispy]

You could also test/narrow down your ground loop by lifting the ground with a cheater plug on the units with grounded plugs....

 

[Pigeon]

The ground loop is between the PC and the Genelecs. It is the connection between the sub and these that you would have to tackle.

I would suggest either of the following options:
1. Make custom RCA -> XLR cables with only two connections: Signal --> hot (pin 2) and Ground --> cold (pin 3).
or
2. 2x RCA --> 1/4" TS cable --> Behringer HD400 --> 2x 1/4" TRS to XLR (balanced) cable.

Unfortunately, when using this with a floating signal source like the tablet, you could get a new problem. With the sub floating, either the HD400 or the 8030 input stage may be subjected to considerable common-mode input voltage due to capacitive leakage across the sub's power transformer, leading to hum intrusion. In this case, an additional earth connection should be provided at the sub - not sure where best to attach it in this case. That, unfortunately, would introduce a ground loop between the PC and the sub!

So I'm afraid you may have to decide between either the PC or the tablet.

The E30 is unlikely to improve anything, I don't think it provides any galvanic isolation (which would be another possible solution). USB isolators may be worth researching, but no idea how well a hi-res DAC would work with these (basic ones are generally restricted to USB 1.1 data rates).

A wild mix of consumer audio (unbalanced, floating) and pro audio (balanced, grounded) as seen here is generally problematic and thus to be avoided. As adding balanced outputs to a PC is relatively inexpensive compared to the rest (sub-€200 for a decent audio interface, 200-300 for a DAC) and off-the-shelf 3.5 mm to 2x XLR cables should get the job done for a tablet, I'd suggest reconsidering your priorities WRT the sub. Maybe a JBL 310S instead?

Is the photo above the option 1 you are talking about? I connected the sub and the 8030 with the rca to xlr cable, which was answered that I worked as in the picture above, unfortunately, the noise was the same. Not sure, but it seems to have gotten smaller.

I found a new solution, but when I connect the 8030 and the sub two separately using the Y connector on the pc, the noise disappears when the pc is turned on, and noise occurs when the pc is turned off. For now, I will use it like this.

The hd400 is the first thing I see. Can I use sub-rca to ts-hd400-trs to xlr-8030c? The noise is annoying when the computer is turned off, so I think it's worth a try.

Thank you for answer!

 

[Pigeon]

You could also test/narrow down your ground loop by lifting the ground with a cheater plug on the units with grounded plugs....

The plug of the subwoofer is a thin plug with no grounding part.
I've covered all the grounding parts of the 8030c and the PC socket with insulating tape. Can't I do this in this way?
I don't understand what you said. Thank you for your sincerity.

 

[Pigeon]

Come to think of it, I didn't use the type of noise. it is high frequency and crackling noise.

 

[Chrispy]

The plug of the subwoofer is a thin plug with no grounding part.
I've covered all the grounding parts of the 8030c and the PC socket with insulating tape. Can't I do this in this way?
I don't understand what you said. Thank you for your sincerity.

Sort of makes it mutual. The grounding parts? But if it is high frequency sounds more like amp hiss than ground loop....

 

[Pigeon]

Sort of makes it mutual. The grounding parts? But if it is high frequency sounds more like amp hiss than ground loop....

not hiss. The 8030's default hiss and high-frequency noise are clearly different. I've used the 8030 before, so I can tell hiss apart.

 

[AnalogSteph]

Can I use sub-rca to ts-hd400-trs to xlr-8030c? The noise is annoying when the computer is turned off, so I think it's worth a try.

Yes, that's exactly what I meant by option 2. Quite a common setup when connecting nearfields to a PC.