KEF x300 Sound Feedback

Andybtsn

Andybtsn

Andybtsn

Don
Joined
23 Oct 2005
Posts
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Location
North Yorkshire
Hi guys,

Any reason why my KEFs produce such a horrible noise when not being used? They are plugged in via USB to my PC. It tends to be that I can unplug the USB, plug it back in and they don't have any horrible static noise for a few mins but it soon starts up again. I assume interference from something but I have kept most of the wires pretty isolated. It's not massively loud but does my head in!! Anything I can do to reduce it? I tried one of those USB jitterbug things but didn't help.

Cheers
 
It's almost certainly a ground loop issue.

I use a ifi iDefender powered using a ifi iPower2 to solve this This will break the ground loop that is occuring between monitors and computer.
 
yeah ground loop.

What if you use a portable Mp3 player into the line level input?

If those speakers had optical digital input then you could try that, optical doesn't suffer from ground loop as it's electrically isolated.

Wireless speakers? WHat's it like using BT from phone to speaker?
 
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Andybtsn said:
Hi guys,

Any reason why my KEFs produce such a horrible noise when not being used? They are plugged in via USB to my PC. It tends to be that I can unplug the USB, plug it back in and they don't have any horrible static noise for a few mins but it soon starts up again. I assume interference from something but I have kept most of the wires pretty isolated. It's not massively loud but does my head in!! Anything I can do to reduce it? I tried one of those USB jitterbug things but didn't help.

Cheers
Click to expand...
Off topic but do yours ever go into standby when connected via USB?
 
SoundsGood said:
Off topic but do yours ever go into standby when connected via USB?
Click to expand...

I want to say no, I thought they were overheating hence the noise. WHy do you ask?

I will try the optical input, IIRC this option produced even more feedback when I last tried it but I had the USB plugged in too. I will remove the USB cable and try it.
 
Tried the aux in and it was worse. Even moving my mouse caused noise to come out of the speaker!

This is the rear for the record. Happy to buy some kit and send it back if it makes no difference.

0Qn3Q8h.jpeg
 
The noise is also so inconsistent. I have just unplugged everything, including my laptop from the power and turned the speakers back on. So far, it's all silent; they're on (not on standby); I just know soon I will hear that horrible hiss again!
 
Some questions

1) What is the aux in? Is it optical or some form of analogue connection?
2) So the noise from the speakers has gone with the laptop on battery power only?
3) Was all this latest testing done with USB from the laptop disconnected?
 
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JasonM said:
Some questions

1) What is the aux in? Is it optical or some form of analogue connection?
2) So the noise from the speakers has gone with the laptop on battery power only?
3) Was all this latest testing done with USB from the laptop disconnected?
Click to expand...

It's just a 3.5mm jack, it works, but the feedback is much worse than USB.
It has gone, I have plugged the laptop back in, the USB-C dock is plugged back in, where it gets its power and everything else USB. I predict it will come back though as I have used the laptop away from the dock before so not confident, especially as nothing has changed!
Yes the USB was disconnected.

hornetstinger said:
If they're wireless speakers with BT function what's it like casting to them?

Try a portable Mp3 player with 3.5mm output and see how that is.
Click to expand...

No wireless unfortunately, they're KEF X300A if you wanted to look at the spec.

I don't have a MP3 player I'm afraid, I did use the laptop away from power etc in the 3.5mm jack and the feedback was still present.
 
Andy,

What is almost certainly happening is noise is coming from both the 3.5mm and USB. You know the noise is from the laptop as it's happening when you move the mouse.

As hornet says, Optical is better as it's galvanic but looks like you don't have optical input.

The fact the noise went away with laptop undocked means it's probably related to laptop charging, or laptop AC/DC transformer.

There is another way noise can get from the laptop to the speakers, and this is via the mains cables, especially if they share the same mains extension. Noise travels from the laptop back into the shared mains extension, then back into the monitors via their mains transformers. However because the noise is so loud it's almost certainly coming from the 3.5mm, or USB ports this way. It is worth plugging the laptop away from the mains plugs for the monitors to eliminate and see if that effects anything.
 
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Thanks for the help gents. The feedback is still gone! I'm still perplexed by this as it's been going on for months; the only thing I actually changed was plug into the other USB port on the laptop, which is on the other side to the power; maybe the issue?!

@SoundsGood, you have got me thinking about the standby part, they never go into standby anymore, they used as they used to make a horrible sound when they did.
 
Andybtsn said:
Thanks for the help gents. The feedback is still gone! I'm still perplexed by this as it's been going on for months; the only thing I actually changed was plug into the other USB port on the laptop, which is on the other side to the power; maybe the issue?!

@SoundsGood, you have got me thinking about the standby part, they never go into standby anymore, they used as they used to make a horrible sound when they did.
Click to expand...
Mine don't go into standby on USB either unless I turn off the device they're connected to. It works ok with 3.5mm.
 
I had so many issues when I had those speakers. Had to have the power supply replaced twice on separate occasions, luckily they were under warranty.
 
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