Sub noise

[sublover]

hey guys,

i have a wiim ultra and a audiolab 9000p - kef ls50 meta & Perlisten R8s sub.

i recently found out that the sub rca is a little bit noisy. If i power off the sub its a bit lower and when i disconnect the rca cable from the Ultra to the sub the noise is gone. How can i solve this?

 

[hoohoohoo]

hey guys,

i have a wiim ultra and a audiolab 9000p - kef ls50 meta & Perlisten R8s sub.

i recently found out that the sub rca is a little bit noisy. If i power off the sub its a bit lower and when i disconnect the rca cable from the Ultra to the sub the noise is gone. How can i solve this?

Does the hum persist when the RCA cable is connected to the sub but not the Ultra?
Are all the devices using the same power circuit or power strip?
Does the hum change if you touch the RCA connector shell?
Do you have a cable TV coax in your setup? Try disconnecting it.
Do you have a PC or other HDMI cable in your setup? Try disconnecting it.
If you have other devices, try disconnecting one at a time while leaving the sub cabling engaged.
Is the RCA cable touching a power cable? Separate them.
Have you tried a different RCA cables? They may have different shielding capabilities.
Do you have any specific settings on the sub that we should consider?

 

[sublover]

Hi HoohooHoo

Thanks for the suggestions. I tested a few things.

The hum is still present when the sub is turned off and the RCA cable is connected to the sub and WiiM Ultra. As soon as I remove the RCA cable from the subwoofer, the hum disappears completely.
The subwoofer is currently connected to a different power outlet than the rest of the system, which reduced the hum slightly but did not eliminate it.
There is no cable TV coax connected in the system. I do have HDMI connected from my TV, but disconnecting it did not change the hum.
I also tried different RCA cables and the result is the same. The cable is not touching any power cables.
So it seems the noise is coming through the RCA ground path when the sub is connected.

 

[slartibartfast]

Hi HoohooHoo

Thanks for the suggestions. I tested a few things.

The hum is still present when the sub is turned off and the RCA cable is connected to the sub and WiiM Ultra. As soon as I remove the RCA cable from the subwoofer, the hum disappears completely.
The subwoofer is currently connected to a different power outlet than the rest of the system, which reduced the hum slightly but did not eliminate it.
There is no cable TV coax connected in the system. I do have HDMI connected from my TV, but disconnecting it did not change the hum.
I also tried different RCA cables and the result is the same. The cable is not touching any power cables.
So it seems the noise is coming through the RCA ground path when the sub is connected.

How high have you set the gain on the sub?

 

[sublover]

Hi Slartibartfast, gain is unchanged had it with nad c700v2 nad c399 and now with wiim & audiolab 9000.

Im not sure if its gain related because with the sub turned off and rca left connected i still hear it.

im so enthusiast about wiim Ultra and i love it but if the sub output is not 100% i cant use it . Kefs ls50 meta needs subs.

 

[slartibartfast]

Hi Slartibartfast, gain is unchanged had it with nad c700v2 nad c399 and now with wiim & audiolab 9000.

Im not sure if its gain related because with the sub turned off and rca left connected i still hear it.

im so enthusiast about wiim Ultra and i love it but if the sub output is not 100% i cant use it . Kefs ls50 meta needs subs.

What do you mean by "sub turned off"? You can easily tell if is gain related by changing the gain. I have mine set to 50% on the dial and +5dB in the WiiM sub settings since higher sub gain produced audible noise from the sub.

 

[BowsAndArrows]

does the hum change at all when you move cables around or touch the chassis of any device in your system?
does the hum change in volume when you change the volume or is it constant - even at 0 and when no music is playing???
i would also try disconnecting one cable at a time and see if that results in the hum disappearing. at the moment only the connection to the sub directly from the ultra to the sub has this effect, right?
these are all trying to confirm that this is indeed a DC ground loop...

some subs have a "ground lift" toggle. (or you can try a 2-pronged plug as another method) this can also get rid of DC ground loops

 

[Wiimer]

The subwoofer is currently connected to a different power outlet than the rest of the system, which reduced the hum slightly but did not eliminate it.

Have you already tried connecting the Sub's power supply to the same power strip as your system?

 

[brink]

hey guys,

i have a wiim ultra and a audiolab 9000p - kef ls50 meta & Perlisten R8s sub.

i recently found out that the sub rca is a little bit noisy. If i power off the sub its a bit lower and when i disconnect the rca cable from the Ultra to the sub the noise is gone. How can i solve this?

Try a high quality sub cable.

 

[Doublej]

I am assuming you are in the US.

Using a receptacle tester, make sure each power receptacle is wired properly.

As suggested, try a ground lifter plug on the sub's power cord.

You can try switching the orientation of the power cord at the back of WiiM, though I would not expect it to make a difference.

You should be able to determine if all of your gear is plugged into the same side of the electrical panel, e.g. Sub, WiiM, and Amp are plugged into even number circuits or odd numbered circuits. If not, try plugging everything into same side of the electrical panel.

 

[sublover]

Hi guys, thanks for replying. I will try all suggeations and report back. Im from the Netherlands. REW and umik 2 showed 150hz noise. 3t harmonics from 50hz

 

[sublover]

if i touch the cables, rca wiim ultra output my speakers almost exploded. i dont dare to do it again (this was not sub rca)

i tried all components 1 socket no luck. If i put the sub on a DJI 500 poweramp it will solve it for 70% on and off the sub amp.

but if i power down the sub i still hear 30% noise. The sub is powered off.
But when i unplug the rca from the sub amp than the noise is gone.

 

[harkpabst]

@sublover ==>

Does the hum persist when the RCA cable is connected to the sub but not the Ultra?

<==

What do you mean by "sub turned off"?

but if i power down the sub i still hear 30% noise. The sub is powered off.
But when i unplug the rca from the sub amp than the noise is gone.

If the sub is really off, it cannot and does not amplify any signal coming from the WiiM Amp Ultra, because ... well ... no power, no amplification.

I have mine set to 50% on the dial and +5dB in the WiiM sub settings since higher sub gain produced audible noise from the sub.

The idea behind this comment is simple: Does the hum vary in loudness when you increase the gain (or volume setting, we don't know how the control is labelled on your actual sub) on your subwoofer? Try decreasing the volume on the sub itself and increase the level in the WiiM Home App.

if i touch the cables, rca wiim ultra output my speakers almost exploded. i dont dare to do it again (this was not sub rca)

You definitely should, because if this happens when just touching the cables, something is severely wrong here. I cannot say what is causing the issue, but there is a real issue and you should definitely resolve it for safety reasons! This must not happen!

If i put the sub on a DJI 500 poweramp it will solve it for 70% on and off the sub amp.

I'm not sure what you are referring to as 70 %. Does it only solve the problem in ~70 % of all cases when you try it? If so, the WiiM Ultra cannot be the root cause if its subwoofer output isn't even involved.

Could you describe your setup in more detail?

 

[Jay123]

I'm reporting that my SVS sb2000 sub is humming a little without the sub even having the RCA cables connected.

Someone suggested that if you put the sub on the same electrical outlet as the TV, Wiim, powered speakers, would that help? I think that's a good idea for me too.

I have the same problem (small hum), it doesn't even start every time I turn on the sub. So it's definitely some kind of ground loop problem. I'll test it later.

 

[Doublej]

Something is definitely very wrong if you touch the subwoofer cable and the output changes at the speakers. You definitely want to get to and resolve the root cause of the problem. Since you said the hum existed with NAD gear as well, I suspect something is funky with the Sub I would contact Perlisten and get their take on things.

 

[slartibartfast]

I'm reporting that my SVS sb2000 sub is humming a little without the sub even having the RCA cables connected.

Someone suggested that if you put the sub on the same electrical outlet as the TV, Wiim, powered speakers, would that help? I think that's a good idea for me too.

I have the same problem (small hum), it doesn't even start every time I turn on the sub. So it's definitely some kind of ground loop problem. I'll test it later.

My BK sub had a slight hum issue. I called the manufacturer and explained the problem and they sent me a replacement mains lead with a DC blocking filter which fixed the issue. I don't know if SVS subs are similar in that respect.

 

[Jay123]

My BK sub had a slight hum issue. I called the manufacturer and explained the problem and they sent me a replacement mains lead with a DC blocking filter which fixed the issue. I don't know if SVS subs are similar in that respect.

Thanks for the reply. That little hum doesn't even correlate with how much volume I put on the subwoofer. It's just a little hum that miraculously appears, about every 15 times, when that subwoofer turns on.

The question is about an old subwoofer that I bought used from a Hifi store in Finland a while ago. If I remember correctly they gave me a 1 month warranty on it.

What I personally think is causing that little hum is so-called dirty electricity. I think it's picking up interference, either from the grounding or from the fact that there are a lot of other devices on that same extension cord.

I need to test it a bit, on different plugs and so on. I would think that the sub is not broken, and I think I will find a solution to that problem, a bit later. Thank you

 

[sublover]

@Jay123

Svs plate amps produce always a slight hiss. completely normal, what is not normal the hiss or groundloop can be heard on the mains. I never had this. When i sold my nad c399 few weeks ago i didnt heard a hiss. Now with my new setup with wiim i can hear it.

 

[sublover]

@harkpabst

thanks for your detailed replys

my setup:

Speakers : LS50 meta
Sub : Perlisten R8s
Amp. : audiolab 9000p ( and a spare nad c268)
Wiim Ultra as pre amp streamer

all are powered on the same powersocket. (netherlands 50hz)

audioquest RCA cables
subcable clicktronic

So if i turn on the streamer > amp > sub i can hear a slight hiss hum / 150hz noise from the speakers. 150hz measured with REW and umik 2.

If i turn the subwoofer off... no power... I can still hear it but slightly less. Yes the power is off wtf... Than i remove the rca cable from sub to wiim. So no connection at all the noise is gone.

please feel free and ask me more. Im gratefull for all the help.

my guestimation is that the rca connections on the wiim are not the world greatest. Or maybe a faulty unit i dont know. I will buy another rca cable and a dc blocker.

 

[anonyless]

@harkpabst

So if i turn on the streamer > amp > sub i can hear a slight hiss hum / 150hz noise from the speakers. 150hz measured with REW and umik 2.

at last you clarified that the hum is coming from your speakers, not from your sub.
this is a common issue with the Ultra, I experienced the exact same thing when I first connected a sub to it - slight hum (ground loop noise) from the speakers. replacing RCAs won't help.
assuming you use analog output from the Ultra to your amp,
try connecting a DAC (any cheap DAC will do) from the Ultra optical out to the DAC , and its RCA output to your amp. that's what solved it for me.