How do i fix the hum on my KRK's?

dequo · Post by **dequo** » Sun Sep 14, 2008 6:20 am

i assume i have 'dirty' ac power as the hum is still there when there is no input and does not increase in volume when i turn it up at the rear. so i can only really hear it when im listening to something quietly.

ive read that i need a ground loop isolator? the only ones i can fine are rca in/out but i think i need it on the actual power outlet?

Sharmaji · Post by **Sharmaji** » Sun Sep 14, 2008 2:11 pm

are you using balanced (TRS or XLR) cables?

dequo · Post by **dequo** » Sun Sep 14, 2008 2:46 pm

no, im using unbalanced 1/4'. but when i said there was hum with no input i meant without any cables plugged in the back at all...

justrob · Post by **justrob** » Mon Sep 15, 2008 3:33 am

use a "ground lift" on the ac cables for your speakers. Its a little plastic thing that takes a 3 prong plug, and makes it two prong. should fix the problem.

dequo · Post by **dequo** » Mon Sep 15, 2008 3:40 am

mmm i tried cutting the earth pin off of a power cable (dw i have spares) and had no effect..

is it possible that i have 2 faulty krk's? they both make the same hum noise.

justrob · Post by **justrob** » Mon Sep 15, 2008 4:16 am

thats weird. If you don't have any audio cables in your speakers, It might be. you try lifting the ground on the ac cable of your computer?

what's the hum sound like, is it a consistent hum, or is it all digital and sparatic?

djshiva · Post by **djshiva** » Mon Sep 15, 2008 4:47 am

i bet money it's a ground loop.

dequo · Post by **dequo** » Mon Sep 15, 2008 6:25 am

if it was a ground loop problem wouldnt them hum have stopped when i used the power cable with the earth removed? (i disconncet earth not ground right?)

i wouldnt feel safe running my pc with no ground... plus theres a few more computers probably on the same line in other rooms.

the hum is consistent, i tried recording it but my mic isnt sensitive enough. it does sound' 50 hz though (im in aus), like when you hear the buzz from a dodgy power line.

its mostly from the tweeter but i can feel the cone moving slightly too.

might try running them at a friends house, but it seems theres so many things that modify the ground level or whatever and there would be problems in any house?

djshiva · Post by **djshiva** » Mon Sep 15, 2008 7:25 am

dequo wrote:if it was a ground loop problem wouldnt them hum have stopped when i used the power cable with the earth removed? (i disconncet earth not ground right?)

i wouldnt feel safe running my pc with no ground... plus theres a few more computers probably on the same line in other rooms.

the hum is consistent, i tried recording it but my mic isnt sensitive enough. it does sound' 50 hz though (im in aus), like when you hear the buzz from a dodgy power line.

its mostly from the tweeter but i can feel the cone moving slightly too.

might try running them at a friends house, but it seems theres so many things that modify the ground level or whatever and there would be problems in any house?

http://www.zzounds.com/item--EBTHUMX

http://www.radioshack.com/sm-buy-the-gr ... 62214.html

various methods that i personally feel more comfortable with than messing with regular plugs.

dequo · Post by **dequo** » Mon Sep 15, 2008 8:06 am

sapphic_beats wrote:
http://www.radioshack.com/sm-buy-the-gr ... 62214.html

various methods that i personally feel more comfortable with than messing with regular plugs.

how do these work? there must be another cable connecting to the AC power or something right?

so this would be my my wiring....

PC-----sampler(sp404)----ground loop isolator-----KRK unbalanced input

sorry about all the questions/questioning, i just want to be sure before i buy one of these things... what i dont get is how putting this on my rca inputs would have an effect as the hum is there when there is no input at all.

sdm · Post by **sdm** » Mon Sep 15, 2008 8:29 am

Anyone know if you can get the some kind of earth removal pin plug for a UK plug?

If not, anyone know where to get those phono isolators where they're cheap and preferably not huge!

Thanks!

dequo · Post by **dequo** » Mon Sep 15, 2008 1:05 pm

and yeah its more of a buzz then a hum if that makes any difference

how long does the warrantee on krk's last?

daft cunt · Post by **daft cunt** » Mon Sep 15, 2008 5:11 pm

dequo wrote:and yeah its more of a buzz then a hum if that makes any difference

how long does the warrantee on krk's last?

Most probably a ground loop as Sapphic said.
Try plugging them on a dedicated receptacle i.e. without any other devices.

agus69 · Post by **agus69** » Mon Sep 15, 2008 6:11 pm

get yourself a Furman power conditioner. it will solve ALL your dirty AC power problems.

switchdubs · Post by **switchdubs** » Mon Sep 15, 2008 6:59 pm

If there making noise with nothing plugged into them its not a ground loop. One of mine developed a fault and was ginving off a nasty hum, (something to do with one of the amps??) i had to send it back to be repaired. It seems strange that both of yours would develope such a fault at the same time tho.

dequo · Post by **dequo** » Tue Sep 16, 2008 8:01 am

switchdubs wrote:If there making noise with nothing plugged into them its not a ground loop. One of mine developed a fault and was ginving off a nasty hum, (something to do with one of the amps??) i had to send it back to be repaired. It seems strange that both of yours would develope such a fault at the same time tho.

how long did it take/cost to get repaired?

switchdubs · Post by **switchdubs** » Tue Sep 16, 2008 10:44 am

The repair was free under warranty, but i got them from turnkey and because they went into adminstration i had to stump up to get them to posted to the repair centre in london. It took about two weeks, which isnt bad for a repair turn around seeing as you get back the speaker you sent. Give krk a ring and see if you can trouble shoot over the phone, if no luck they can book the repair in for you.
http://www.krksys.com/contact.php

dequo · Post by **dequo** » Tue Sep 16, 2008 12:41 pm

i hope it doesnt come to that

posting these bad boys from aus to london would cost a shitload (about 200 each way)... dammit

How do i fix the hum on my KRK's?

How do i fix the hum on my KRK's?

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