KRK problems

Suposium

New member
Hey guys, I'm trying to find out why my power supply is interupting with my new KRK's, It's making like a buzzing sound.


Firstly The power supply can have 100-240 volts on input but it can supply 4.74 amps to the laptop.


secondly the power requirments for the laptop is 4.74 amps and 19 volts


My KRK Rokits 5" are connected via a USB Audio interface (Numark DJ|iO) to my laptop


here is a picture, I don't know if it's useful, I've only got the monitors that close together for testing purposes.

mFZLdUh.jpg
 
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how much power does the laptop require - what is the quoted wattage figure (W)?

With the power supply, what voltage is putting out (not the 110-240V, but the other side of the equation where the 4.74A is also found)?

and before anybody suggests ground loop
- it is more likely to be ac ripple on the power supply as it tries to provide more wattage than it is rated for to the laptop
- essentially voltage times current, which in this case appears to be 90.6W
- a ground loop, on the other hand, occurs when devices in a system have different ground references
- the laptop power supply is not likely to have a ground reference fed to the laptop, so this will not be the problem.....

pics of the labels that show these figures on the power supply and the laptop would help
 
It's putting out 19 volts on the output side. i couldnt see that before

EDIT: I also forgot to say when i unplug the charger it stops making the buzzing sound, also it's 90 watts, i believe the speakers require 90 watts aswell
 
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I had that problem and I put 3 prong adapters at the end of both krk plugs and the laptop adapter and I dont hear buzzing anymore...I have a bunch of electrical stuff around my work area.

30w1-32200.jpg

Also did you try unplugging the adapter and running on battery only to see if the buzz goes away?
 
1) and whilst you don't hear the buzzing you are also opening yourself to severe issues to do with electrocution if one or more of those devices develop an earthing fault; if the earth is not connected the residual current detector (aka the earth leakage detector) will not kick on (off) and you will be electrocuted before you realise that there is a problem with live electricity being grounded in your device.

i.e. don't do this ever - remove the grounding from the device as you will remove all the mandated protections in your electrical wiring at home or work related to ground leakage

2) the op has already stated that the buzzing does not exist when the power supply is not connected

back to the op:

In what manner are you connecting the krk's to your laptop? cabling, interface, etc
 
I've been wanting to get rid of some of the stuff I have a desktop computer that I no longer use...then a few pieces of gear.
I usually just turn the power off everything then flip the surge switch.
 
With a USB audio Interface.

and how is that powered? - via the usb ports or it's own power source???

I've been wanting to get rid of some of the stuff I have a desktop computer that I no longer use...then a few pieces of gear.
I usually just turn the power off everything then flip the surge switch.

I'm sorry, I don't follow what you are saying here???
 
It's powered by the usb ports, I'm thinking of getting it's own power supply. Do you think that could fix it?
 
more than likely - the USB spec says that a port should be able to deliver 5v@2A, but most implementations actually current limit that to 0.5A per port, causing a current overdraw issue which can lead to the kind of buzzing you describe as the power supply struggles to provide the required current for the device attached.

this may not be noticeable when operating off battery power (unusually so, it is more normally the other way around), but once the power supply is plugged may become an issue

what is your interface - this will get to the nitty gritty of the power required and why it may be doing what it is.....
 
so, yes, I would get the additional power supply - this will eliminate the need to draw power from the computer and creating other issues - it requires 1A of current @ 6V meaning it needs 6W of power - the likelihood is that the USB ports are only providing 2.5W of power, so the interface is struggling and creating ac ripple on the power lines and subsequent audio out, rendering as a buzz
 
Where's the best place to get a power supply for the interface in Sutherland shire area?
 
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It's still giving me problems, It's not receiving any power from the power supply i bought, but from the USB port, when i took the USB port out it was turned off, but when i take the power supply in and out, the speakers pop.
 
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